Amy, B.W. (2005). West Nile virus. Journal of the Mississippi State Medical Association 46(5): 138-140.
Descriptors: West Nile fever epidemiology, West Nile virus, hotlines, Mississippi, prevention and control.
Anon (2006). West nile virus a looming deadly threat for liver transplantation. Transplantation 82(1 Suppl 2): 150.
Descriptors: West Nile virus, liver transplantation, deadly threat, infection, abstract.
Anon (2006). West nile virus activity--United States, January 1-November 7, 2006. MMWR. Morbidity and Mortality Weekly Report 55(44): 1204-1205.
Abstract: This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m. Mountain Standard Time, November 7, 2006. A total of 41 states and the District of Columbia had reported 3,830 cases of human WNV illness to CDC.
Descriptors: West Nile fever, bird diseases, culicidae, horse diseases, rodent diseases, sciuridae, United States, West Nile virus isolation and purification.
Anon (2006). West Nile virus activity--United States, January 1-October 10, 2006. MMWR. Morbidity and Mortality Weekly Report 55(40): 1097-1098.
Abstract: This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m. Mountain Daylight Time, October 10, 2006. A total of 41 states and the District of Columbia had reported 3,135 cases of human WNV illness to CDC. A total of 1,717 (55%) cases for which such data were available occurred in males; median age of patients was 50 years (range: 3 months-99 years). Dates of illness onset ranged from January 6 to September 25; a total of 97 cases were fatal.
Descriptors: West Nile fever epidemiology, West Nile virus isolation and purification, bird diseases, culicidae, horse diseases, rodent diseases, sciuridae, United States.
Anon (2006). West Nile virus activity--United States, January 1-September 12, 2006. MMWR. Morbidity and Mortality Weekly Report 55(36): 996.
Abstract: This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m. Mountain Daylight Time, September 12, 2006. A total of 36 states and the District of Columbia had reported 1,634 cases of human WNV illness to CDC. A total of 921 (57%) cases for which such data were available occurred in males; median age of patients was 51 years (range: 3 months-95 years). Dates of illness onset ranged from January 6 to September 10; a total of 52 cases were fatal.
Descriptors: West Nile fever, humans, birds, humans, United States, fatality reports.
Anon (2006). West Nile virus activity--United States, January 1-August 15, 2006. Morbidity and Mortality Weekly Report 55(32): 879-880.
Abstract: This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m. Mountain Daylight Time, August 15, 2006. A total of 26 states had reported 388 cases of human WNV illness to CDC. A total of 214 (56%) cases for which such data were available occurred in males; median age of patients was 49 years (range: 2-91 years). Dates of illness onset ranged from January 6 to August 10; a total of 13 cases were fatal. A total of 68 presumptive West Nile viremic blood donors (PVDs) have been reported to ArboNET during 2006. Of these, 20 were reported from Nebraska; 18 were reported from Texas; five were reported from California; four were reported from Utah; three each were reported from Oklahoma and South Dakota; two each were reported from Idaho, Iowa, Kentucky, and Mississippi; and one each was reported from Arizona, Colorado, Minnesota, Nevada, North Dakota, Wisconsin, and Wyoming. Of the 68 PVDs, 10 persons (median age: 43 years [range: 18-59 years]) subsequently had West Nile fever.
Descriptors: West Nile fever epidemiology, humans, bird diseases, culicidae, horse diseases, rodent diseases, United StatesWest Nile virus isolation and purification.
Anon (2006). Assessing capacity for surveillance, prevention, and control of West Nile virus infection--United States, 1999 and 2004. Morbidity and Mortality Weekly Report 55(6): 150-153.
Abstract: Indigenous human disease caused by West Nile virus (WNV) was first identified in the United States in August 1999 in the greater New York City area. By the end of 2004, human WNV disease had been reported in all states except Washington, Hawaii, and Alaska, and WNV transmission to humans had been documented by five routes: mosquito bites (principally from Culex spp.), blood transfusions, organ transplantation, transplacental transfer, and breastfeeding. During 1999-2005, a total of 19,525 cases of WNV disease in humans and 771 deaths were reported in the United States. In 2000, CDC first published guidelines for WNV surveillance, prevention, and control and created ArboNET, an electronic surveillance and reporting system. Beginning in 1999, WNV surveillance and prevention activities had been initiated in selected states and large cities through the CDC Epidemiology and Laboratory Capacity (ELC) cooperative agreements for emerging infectious diseases and subsequently expanded to all 50 states, six large cities/counties, and Puerto Rico. In 2005, to assess the capacity of state and large-city/county health departments to conduct WNV surveillance, prevention, and control activities, the Council of State and Territorial Epidemiologists (CSTE), with assistance from the Association of Public Health Laboratories (APHL) and CDC, surveyed WNV programs in the 50 states and six large-city/county health departments. This report describes the results of that assessment, which indicated that all participating states and cities had well-developed surveillance and control programs for human, avian, equine, or mosquito WNV.
Descriptors: public health practice, West Nile fever epidemiology, prevention and control, population surveillance, United States, West Nile virus.
Anon (2005). West Nile virus activity--United States, January 1-December 1, 2005. Morbidity and Mortality Weekly Report 54(49): 1253-1256.
Abstract: West Nile virus (WNV) is the leading cause of arboviral encephalitis in the United States. Originally discovered in Africa in 1937, WNV was first detected in the western hemisphere in 1999 in New York City. Since then it has caused seasonal epidemics of febrile illness and severe neurologic disease. During January 1-December 1, 2005, a total of 2,744 cases of WNV disease in humans were reported in the United States, an increase from 2,359 during the same period in 2004. A total of 1,165 cases were WNV neuroinvasive disease (WNND). WNV infections in humans, birds, mosquitoes, and nonhuman mammals are reported to CDC through ArboNET, an Internet-based arbovirus surveillance system managed by state health departments and CDC. During 2005, WNV transmission to humans or animals expanded into 21 counties that had not previously reported transmission and recurred in 1,196 counties where transmission had been reported in previous years. This report summarizes provisional WNV surveillance data through December 1, 2005, and highlights the need for ongoing surveillance, mosquito control, promotion of personal protection from mosquito bites, and research into additional prevention strategies.
Descriptors: West Nile fever epidemiology, birds, culicidae, dogs, horses, population surveillance, sciuridae, United States, West Nile virus isolation and purification.
Anon (2005). Update: West Nile virus activity--United States, 2005. Morbidity and Mortality Weekly Report 54(43): 1105-1106.
Abstract: This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m. Mountain Standard Time, November 1, 2005.
Descriptors: West Nile fever epidemiology, birds, culicidae, dogs, horses, sciuridae, United States, West Nile virus isolation and purification.
Anonymous (2006). First West Nile Virus screening test approved. FDA Consumer 40(1): 3.
Descriptors: West Nile fever diagnosis, West Nile virus isolation and purification, screening tests.
Anonymous (2005). Summaries for patients. The cost-effectiveness of screening the U.S. blood supply for West Nile virus. Annals of Internal Medicine 143(7): I44.
Descriptors: blood transfusion, blood borne pathogens, West Nile virus, computer simulation, cost benefit analysis, markov chains, humans, nucleic acid amplification techniques, United States.
Notes: Original Report In: Ann Intern Med. 2005 Oct 4;143(7):486-92.
Anonymous (2005). West Nile Virus. The Nurse Practitioner 30(8): 51-52.
Descriptors: West Nile fever diagnosis, West Nile fever prevention and control, West Nile fever transmission.
Anonymous (2005). All you need to know about West Nile virus. Nursing Times 101(26): 28.
Descriptors: communicable diseases, West Nile fever, birds, insect vectors, mosquito control, seasonal changes.
Avalos Bock, S.A. (2005). West Nile virus and the U.S. blood supply: New tests substantially reduce the risk of transmission via donated blood products. American Journal of Nursing 105(12): 34, 36-37.
Descriptors: blood donors, nucleic acid amplification techniques, RNA, viral blood, West Nile fever, United States, West Nile virus.
Averett, E., J.S. Neuberger, G. Hansen, and M.H. Fox (2005). Evaluation of West Nile virus education campaign. Emerging Infectious Diseases 11(11): 1751-1753.
Abstract: We evaluated the 2003 Kansas West Nile virus public education campaign. Awareness was widespread but compliance was low. Spanish-speaking persons were poorly informed. Relevant factors included population segment variability, campaign content, media choice, and materials delivery methods.
Descriptors: health education, program evaluation, West Nile fever, West Nile virus, health surveys, hispanic Americans, Kansas, mass media.
Batalis, N.I., L. Galup, S.R. Zaki, and J.A. Prahlow (2005). West Nile virus encephalitis. American Journal of Forensic Medicine and Pathology 26(2): 192-196.
Abstract: West Nile virus (WNV) is a mosquito-borne virus that has caused a large number of deaths in the United States since the first outbreak in New York City in 1998. The outbreak initially was limited to the northeast but has since spread across the entire continental United States. WNV causes a variety of clinical symptoms, but the most severe consequences result from central nervous system infection, resulting in meningitis, encephalitis, or meningoencephalitis. We present a case of a 62-year-old male with metastatic cancer, who died as a result of WNV encephalitis. This is followed by a discussion on the epidemiology of WNV and a detailed summary of the methods and resources available to make a diagnosis of WNV infection postmortem. The material presented in the discussion should provide the forensic pathologist with all the information necessary to make a diagnosis of WNV infection postmortem. If nothing else, the routine collection and storage of serum, cerebrospinal fluid, and tissue for every case can enable the forensic pathologist to make this diagnosis even in cases in which WNV is not suspected until after autopsy.
Descriptors: mosquito vectors, West Nile fever, brain pathology, carcinoma, small cell therapy, chills, confusion, fever, forensic pathology, lung neoplasms, psychomotor agitation.
Beasley, D.W. (2005). Recent advances in the molecular biology of west nile virus. Current Molecular Medicine 5(8): 835-850.
Abstract: Since the mid-1990s, West Nile virus (WNV) has emerged as a significant agent of arboviral encephalitis in several regions of the world. In 1999, WNV was introduced into the northeastern United States and was associated with an outbreak of encephalitis affecting humans, birds and horses. Subsequently, the virus has spread across the country, and across southern Canada, and in 2002 and 2003 was associated with the largest outbreaks of arboviral encephalitis recorded in the Western hemisphere. Interestingly, the more recent spread of WNV into Mexico, Central America and the Caribbean has not been associated with the high levels of clinical disease observed in North America. This review addresses the most recent results from studies investigating the molecular biology and evolution of WNV, as well as progress in the development of diagnostic and therapeutic reagents.
Descriptors: West Nile fever, West Nile virus, United States.
Beveroth, T.A., M.P. Ward, R.L. Lampman, A.M. Ringia, and R.J. Novak (2006). Changes in seroprevalence of West Nile virus across Illinois in free-ranging birds from 2001 through 2004. American Journal of Tropical Medicine and Hygiene 74(1): 174-179. ISSN: 0002-9637.
Abstract: Of the 5,236 birds sampled for antibodies to West Nile virus (WNV) in Illinois from 2001 through 2004, 348 (6.6%) birds were seropositive. Our multiple year surveillance identified several avian species that had particularly high percentages of seropositive individuals. The importance of these species in the enzootic and/or epizootic transmission of WNV is discussed relative to their regional abundance and literature on host competency. The species with the highest exposure rates to WNV differed both temporally and regionally. In general, birds that bred or were born in Illinois were more likely to have antibodies than transient birds. There was also a significant difference in the seroprevalence between adults (12.1%) and juveniles (5.5%), indicating that the acquired antibody response from previous years is a critical concern when interpreting seroprevalence rates in wild-caught birds. The most common hosts for St. Louis encephalitis virus were also the most common hosts for WNV, which strongly supports the role of similar vectors for both flaviviruses. Avian species with high WNV seroprevalence rates tended to be those that bred throughout the year, have open cup nests, and live in close proximity to humans.
Descriptors: aves, age, viral disease prevalence relations, viral diseases, West Nile virus, host records, prevalence, annual changes and age relations, Illinois, viral disease prevalence and host records.
Bowman, C., A.B. Gumel, P. van den Driessche, J. Wu, and H. Zhu (2005). A mathematical model for assessing control strategies against West Nile virus. Bulletin of Mathematical Biology 67(5): 1107-33.
Abstract: Since its incursion into North America in 1999, West Nile virus (WNV) has spread rapidly across the continent resulting in numerous human infections and deaths. Owing to the absence of an effective diagnostic test and therapeutic treatment against WNV, public health officials have focussed on the use of preventive measures in an attempt to halt the spread of WNV in humans. The aim of this paper is to use mathematical modelling and analysis to assess two main anti-WNV preventive strategies, namely: mosquito reduction strategies and personal protection. We propose a single-season ordinary differential equation model for the transmission dynamics of WNV in a mosquito-bird-human community, with birds as reservoir hosts and culicine mosquitoes as vectors. The model exhibits two equilibria; namely the disease-free equilibrium and a unique endemic equilibrium. Stability analysis of the model shows that the disease-free equilibrium is globally asymptotically stable if a certain threshold quantity (R0), which depends solely on parameters associated with the mosquito-bird cycle, is less than unity. The public health implication of this is that WNV can be eradicated from the mosquito-bird cycle (and, consequently, from the human population) if the adopted mosquito reduction strategy (or strategies) can make R0<1. On the other hand, it is shown, using a novel and robust technique that is based on the theory of monotone dynamical systems coupled with a regular perturbation argument and a Liapunov function, that if R0>1, then the unique endemic equilibrium is globally stable for small WNV-induced avian mortality. Thus, in this case, WNV persists in the mosquito-bird population.
Descriptors: theoretical models, West Nile fever, birds, communicable disease control methods, culicidae, insect control methods, insect repellents, protective clothing, West Nile virus.
Bradbury, J. (2005). Toll gate for West Nile virus brain entry. Lancet Infectious Diseases 5(1): 9.
Descriptors: blood brain barrier, membrane glycoproteins, West Nile fever, West Nile virus, culicidae, mice, toll-like receptors.
Briese, T. and K.A. Bernard (2005). West Nile virus--An old virus learning new tricks? Journal of Neurovirology 11(5): 469-475.
Abstract: West Nile virus (WNV) has spread across the United States causing annual outbreaks since its emergence in 1999. Although severe disease develops only in about 1% of infections, WNV has claimed a total of 564 lives in the 5 years from 1999 to 2003. Observation of flaccid paralysis due to WNV infection at a higher incidence than previously documented and the devastating mortality recorded in infected American bird species triggered concerns about a potentially enhanced virulence of this virus. Here we summarize recent observations made during the American outbreaks regarding host range and transmission modes of WNV, and discuss epidemiological aspects of the emergence of this pathogen in the new habitat.
Descriptors: disease outbreaks, West Nile fever, West Nile virus, transmission of animal diseases, arthropod vectors, birds, disease reservoirs, mortality, pregnancy complications, United States.
Busch, M.P., S. Caglioti, E.F. Robertson, J.D. McAuley, L.H. Tobler, H. Kamel, J.M. Linnen, V. Shyamala, P. Tomasulo, and S.H. Kleinman (2005). Screening the blood supply for West Nile virus RNA by nucleic acid amplification testing. New England Journal of Medicine 353(5): 460-467.
Abstract: BACKGROUND: The use of nucleic acid amplification tests of "minipools" of 16 samples to screen blood donors for West Nile virus RNA began in July 2003. We report the yield and characteristics of positive donations and the incremental yield and safety of nucleic acid amplification tests of individual donations. METHODS: Reactive minipools were analyzed to identify the individual reactive donations. For the regions with the highest yield on minipool testing, retrospective nucleic acid amplification testing was performed on individual donations that were negative on minipool testing. Reactive donations were confirmed by alternative nucleic acid amplification tests and IgM and IgG tests, and donors were followed to document seroconversion. RESULTS: From July 1 through October 31, 2003, 677,603 donations were prospectively screened for West Nile virus by minipool testing, yielding 183 confirmed viremic donations (0.027 percent, or 1 in 3703 donations). Retrospective individual testing of 23,088 donations from high-prevalence regions that were negative on minipool testing yielded 30 additional units with a low level of viremia, with 14 additional viremic units detected by prospective testing of individual donations late in the 2003 transmission season. Of all the viremic units detected, 5 percent were detected only by individual testing and were negative for IgM antibody, 29 percent were detected by individual testing after IgM seroconversion, and 66 percent were detected by minipool testing. West Nile virus infection was confirmed in both recipients of IgM-negative units that were reactive on individual testing, whereas neither recipient of antibody-positive blood components that were reactive on individual testing was infected. In 2004, prospective testing of individual donations in regions that yielded donations that were reactive on minipool testing resulted in a 32 percent incremental yield of units with a low level of viremia that would have been missed by minipool testing. CONCLUSIONS: Although nucleic acid amplification testing of minipools of blood donations prevented hundreds of cases of West Nile virus infection in 2003, it failed to detect units with a low level of viremia, some of which were antibody-negative and infectious. These data support the use of targeted nucleic acid amplification testing of individual donations in high-prevalence regions, a strategy that was implemented successfully in 2004. Copyright 2005 Massachusetts Medical Society.
Descriptors: blood donors, nucleic acid amplification techniques, viral blood RNA, West Nile fever, West Nile virus isolation and purification, retrospective studies, viremia.
Notes: Comment In: N Engl J Med. 2005 Aug 4;353(5):516-7.
Busch, M.P., D.J. Wright, B. Custer, L.H. Tobler, S.L. Stramer, S.H. Kleinman, H.E. Prince, C. Bianco, G. Foster, L.R. Petersen, G. Nemo, and S.A. Glynn (2006). West Nile virus infections projected from blood donor screening data, United States, 2003. Emerging Infectious Diseases 12(3): 395-402.
Abstract: National blood donor screening for West Nile virus (WNV) RNA using minipool nucleic acid amplification testing (MP-NAT) was implemented in the United States in July 2003. We compiled national NAT yield data and performed WNV immunoglobulin M (IgM) testing in 1 WNV-epidemic region (North Dakota). State-specific MP-NAT yield, antibody seroprevalence, and the average time RNA is detectable by MP-NAT were used to estimate incident infections in 2003. WNV donor screening yielded 944 confirmed viremic donors. MP-NAT yield peaked in August with >0.5% of donations positive for WNV RNA in 4 states. Peak IgM seroprevalence for North Dakota was 5.2% in late September. The average time viremia is detectable by MP-NAT was 6.9 days (95% confidence interval [CI] 3.0-10.7). An estimated 735,000 (95% CI 322,000-1,147,000) infections occurred in 2003, with 256 (95% CI 112-401) infections per neuroinvasive case. In addition to preventing transfusion-transmitted WNV infection, donor screening can serve as a tool to monitor seasonal incidence in the general population.
Descriptors: blood donors, West Nile fever, RNA, viral blood, seasons, sensitivity and specificity, time factors, United State, West Nile virus.
Chang Hua, Hua QunYi, Xiang Xun, Zeng ZhaoWen, and Duan Gang (2005). Recent advances in the study of West Nile virus. Journal of Yunnan Agricultural University 21(1): 77-80. ISSN: 1004-390X.
Descriptors: West Nile virus, diagnosis and prevention, vaccination, epidemiology, pathogenicity, literature review.
Language of Text: Chinese; Summary in English.
Corrigan, R.L., C. Waldner, T. Epp, J. Wright, S.M. Whitehead, H. Bangura, E. Young, and H.G. Townsend (2006). Prediction of human cases of West Nile virus by equine cases, Saskatchewan, Canada, 2003. Preventive Veterinary Medicine 76(3-4): 263-72.
Abstract: In 2003, an outbreak of West Nile virus (WNV) occurred in Saskatchewan, Canada from July to September. One-hundred thirty-three horse cases and 947 human cases were recorded and data were analyzed retrospectively for evidence of clustering to determine if clinical infection in the horse population could be used to estimate human risk of infection with WNV. Kulldorff's scan statistic was used to identify spatial-temporal clusters in both the human and horse cases. In most areas, human clusters were not preceded by horse clusters. In one area, a significant cluster of horse cases preceded human cases by 1 week; however, 1 week does not provide sufficient time for human-health authorities to act and provide advance warning for the public.
Descriptors: disease outbreaks, horse diseases epidemiology, diseases transmission, West Nile fever epidemiology, zoonoses, cluster analysis, horse diseases prevention and control, predictive value of tests, retrospective studies, Saskatchewan epidemiology, space time clustering, time factors, West Nile fever, prevention and control, West Nile fever transmission, West Nile virus isolation and purification.
Crawford, C., D. Hoch, M. Long, and J. Levy (2005). Prevalence of West Nile virus in feral cats. Journal of Veterinary Internal Medicine 19(3): 471. ISSN: 0891-6640.
Descriptors: feral cats, population studies, West Nile virus, ELISA, virus neutralization assay, diagnostic techniques.
Notes: Meeting Information: 23rd Annual Forum of the American College of Veterinary Internal Medicine, Baltimore, Maryland, USA; June 1-4, 2005.
Davis, L.B., E. Hayes, D. O'leary, T. Smith, A. Marfin, A. Hinckley, P. Collins, K. Kniss, and G. Campbell (2005). Age and gender as risk factors for West Nile virus neuroinvasive disease in children in the United States, 1999-2004. American Journal of Epidemiology 161(11, Suppl. S): S113. ISSN: 0002-9262.
Descriptors: children, neuroinvasive disease, meningitis, encephalitis, West Nile virus, risk factors, age, gender, USA.
Notes: Meeting Information: Joint Meeting of the Society for Epidemiologic Research/Canadian Society for Epidemiology and Biostatistics, Toronto, Canada; June 27 -30, 2005.
Davis, L.E., R. DeBiasi, D.E. Goade, K.Y. Haaland, J.A. Harrington, J.B. Harnar, S.A. Pergam, M.K. King, B.K. DeMasters, and K.L. Tyler (2006). West Nile virus neuroinvasive disease. Annals of Neurology 60(3): 286-300.
Abstract: Since 1999, there have been nearly 20,000 cases of confirmed symptomatic West Nile virus (WNV) infection in the United States, and it is likely that more than 1 million people have been infected by the virus. WNV is now the most common cause of epidemic viral encephalitis in the United States, and it will likely remain an important cause of neurological disease for the foreseeable future. Clinical syndromes produced by WNV infection include asymptomatic infection, West Nile Fever, and West Nile neuroinvasive disease (WNND). WNND includes syndromes of meningitis, encephalitis, and acute flaccid paralysis/poliomyelitis. The clinical, laboratory, and diagnostic features of these syndromes are reviewed here. Many patients with WNND have normal neuroimaging studies, but abnormalities may be present in areas including the basal ganglia, thalamus, cerebellum, and brainstem. Cerebrospinal fluid invariably shows a pleocytosis, with a predominance of neutrophils in up to half the patients. Diagnosis of WNND depends predominantly on demonstration of WNV-specific IgM antibodies in cerebrospinal fluid. Recent studies suggest that some WNV-infected patients have persistent WNV IgM serum and/or cerebrospinal fluid antibody responses, and this may require revision of current serodiagnostic criteria. Although there is no proven therapy for WNND, several vaccines and antiviral therapy with antibodies, antisense oligonucleotides, and interferon preparations are currently undergoing human clinical trials. Recovery from neurological sequelae of WNV infection including cognitive deficits and weakness may be prolonged and incomplete.
Descriptors: nervous system diseases, West Nile fever , West Nile virus.
Dean, J.L. and B.J. Palermo (2005). West Nile virus encephalitis. Current Infectious Disease Reports 7(4): 292-296. ISSN: 1523-3847.
Abstract: West Nile virus (WNV) is a small RNA virus. It was first isolated in the blood of a febrile woman in the West Nile district of Uganda in 1937. Although WNV has caused human disease in Africa and Europe since its identification, the first documented human infections occurred in the United States in 1999. Wild birds are the reservoir for WNV, and most transmission to humans occurs after the bite of an infected mosquito. In humans, 80% of infections are asymptomatic and nearly 20% cause a mild self-limiting illness called WNV fever. Less than 1% will develop central nervous system (CNS) infection, which manifests as meningitis, encephalitis, or acute flaccid paralysis. The case fatality rate for CNS infection is approximately 15%. Human vaccine is not available. Personal mosquito protection remains the best prevention, and treatment is supportive.
Descriptors: West Nile virus, RNA virus, encephalitis, brain diseases, wild birds as disease reservoirs, transmission, disease prevention, meningitis.
Deardorff, E., J. Estrada Franco, A.C. Brault, R. Navarro Lopez, A. Campomanes Cortes, P. Paz Ramirez, M. Solis Hernandez, W.N. Ramey, C.T. Davis, D.W. Beasley, R.B. Tesh, A.D. Barrett, and S.C. Weaver (2006). Introductions of West Nile virus strains to Mexico. Emerging Infectious Diseases 12(2): 314-318.
Abstract: Complete genome sequencing of 22 West Nile virus isolates suggested 2 independent introductions into Mexico. A previously identified mouse-attenuated glycosylation variant was introduced into southern Mexico through the southeastern United States, while a common US genotype appears to have been introduced incrementally into northern Mexico through the southwestern United States.
Descriptors: West Nile virus, bird diseases, horse diseases, Mexico, mice, molecular sequence data, United States.
Debiasi, R.L. and K.L. Tyler (2006). West Nile virus meningoencephalitis. Nature: Clinical Practice Neurology 2(5): 264-275. ISSN: 1745-834X.
Abstract: Since its first appearance in the US in 1999, West Nile virus (WNV) has emerged as the most common cause of epidemic meningoencephalitis in North America. In the 6 years following the 1999 outbreak, the geographic range and burden of the disease in birds, mosquitoes and humans has greatly expanded to include the 48 contiguous US and 7 Canadian provinces, as well as Mexico, the Caribbean islands and Colombia. WNV has shown an increasing propensity for neuroinvasive disease over the past decade, with varied presentations including meningitis, encephalitis and acute flaccid paralysis. Although neuroinvasive disease occurs in less than 1% of infected individuals, it is associated with high mortality. From 1999-2005, more than 8,000 cases of neuroinvasive WNV disease were reported in the US, resulting in over 780 deaths. In this review, we discuss epidemiology, risk factors, clinical features, diagnosis and prognosis of WNV meningoencephalitis, along with potential treatments.
Descriptors: West Nile fever epidemiology, United States.
Diamond, M.S. (2005). Development of effective therapies against West Nile virus infection. Expert Review of Anti Infective Therapy 3(6): 931-944.
Abstract: Since its entry into North America in 1999, West Nile virus has spread throughout the USA and Canada, and now annually causes a clinical spectrum of human disease ranging from a self-limiting acute febrile illness to potentially lethal encephalitis. Although no therapy is currently approved for use in humans, several strategies are being pursued to develop effective prophylaxis and treatments. This review describes the epidemiology, clinical presentation and pathogenesis of West Nile virus infection, and highlights recent progress towards an effective therapy.
Descriptors: antiviral agents, pharmaceutical trends, West Nile fever, West Nile virus drug effects, literature review.
Diamond, M.S. and R.S. Klein (2006). A genetic basis for human susceptibility to West Nile virus. Trends in Microbiology 14(7): 287-289.
Abstract: West Nile virus (WNV) infects thousands of humans annually and causes a spectrum of disease ranging from an acute febrile illness to lethal encephalitis. A new study suggests a link between CCR5Delta32 (a common mutant allele of the chemokine and HIV receptor CCR5) and fatal WNV infection. The study highlights a possible risk in targeting this receptor for the prevention and/or treatment of infectious diseases.
Descriptors: genetic predisposition to disease, CCR5 receptors genetics, West Nile fever, mice, West Nile virus, risk factors.
DiMenna, M.A., R.J. Bueno, R.R. Parmenter, D.E. Norris, J.M. Sheyka, J.L. Molina, E.M. LaBeau, E.S. Hatton, and G.E. Glass (2006). Emergence of West Nile virus in mosquito (Diptera: Culicidae) communities of the New Mexico Rio Grande Valley. Journal of Medical Entomology 43(3): 594-599.
Abstract: The first appearances of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) in New Mexico were reported in late summer to early fall 2002. Several dead birds tested positive for WNV, and 78 equine cases were confirmed. All mosquito pools tested (n = 268) were negative. A statewide surveillance program was launched in May 2003 to study the emergence and spread of this new arbovirus in mosquitoes from the Rio Grande valley. Mosquitoes were trapped at 32 sites along a 750-km stretch of the Rio Grande valley. Sites were trapped for one night either weekly or biweekly, by using CO2-baited CDC light traps and gravid traps. Pools of captured mosquitoes were tested for WNV by reverse transcription-polymerase chain reaction. By mid-July 2003, WNV levels in the mosquito population had reached levels that were detectable by the surveillance program. Positive pools of mosquitoes were found in the Rio Grande valley from mid-July through late September. In total, 75 positive pools were found, from sites throughout the study area. The predominant species infected with WNV in this region were Culex tarsalis (Coquillett) in rural areas, and Culex salinarius (Coquillett) and Culex pipiens quinquefasciatus (Say) in urban areas. There were 202 human cases and 438 equine cases of WNV in New Mexico in 2003, which corresponded well in time with the positive mosquitoes. Our results seemed to be consistent with introduction of WNV in late summer 2002, followed by a period of transmission and amplification cycles between local avian hosts and mosquito vectors.
Descriptors: West Nile virus, horse diseases, insect vectors, New Mexico, seasons, West Nile fever transmission.
Docherty, D.E., M.D. Samuel, C.A. Nolden, K.F. Egstad, and K.M. Griffin (2006). West Nile virus antibody prevalence in wild mammals, southern Wisconsin. Emerging Infectious Diseases 12(12): 1982-1984. ISSN: 1080-6040.
Descriptors: wild mammals, southern Wisconsin, West Nile antibody, population studies, disease transmission.
Drebot, M.A. and H. Artsob (2005). West Nile virus. Update for family physicians. Canadian Family Physician Medecin De Famille Canadien 51: 1094-1099.
Abstract: OBJECTIVE: To review the epidemiology and disease manifestations of West Nile virus (WNV) in North America and to describe the current status of therapeutic approaches and vaccines for treating or preventing viral illness. QUALITY OF EVIDENCE: Since 1999, research initiatives investigating the ecology, epidemiology, and biology of WNV have increased substantially. These studies provide a foundation for understanding current activity and predicting future activity and for describing the effect of WNV on human health. MAIN MESSAGE: West Nile virus is transmitted to humans primarily through bites from infected mosquitoes. Most people infected have no symptoms; a few have clinical manifestations ranging from febrile illness to neurologic syndromes and possibly death. Risk of serious disease increases with age, and substantial long-term morbidity has been observed in patients who develop severe neurologic illness. No specific antiviral therapy or vaccine currently exists. CONCLUSION: West Nile virus has established itself in North America and has become an important public health concern. Decreasing risk of virus-associated illness requires seasonal preventive and control measures.
Descriptors: West Nile fever diagnosis, West Nile fever epidemiology, Canada, family practice.
Esteves, A., A. Almeida, R. Galao, R. Parreira, J. Piedade, J. Rodrigues, C. Sousa, and M. Novo (2005). West Nile virus in Southern Portugal, 2004. Vector Borne and Zoonotic Diseases. 5(4): 410-413. ISSN: 1530-3667.
Descriptors: West Nile virus, disease detection, insect vectors, Culicidae, Culex pipiens, Culex univittatus, nucleotide sequences, sequence homology, phylogeny, epidemiological studies, Portugal, infection-rate.
Everson, K. (2006). West Nile virus up in 2005. Canadian Medical Association Journal 174(1): 21.
Descriptors: birds virology, climate, West Nile fever mortality, Canada, disease reservoirs, mortality trends, movement, population dynamics, seasons, zoonoses.
Fonseca, K., G.D. Prince, J. Bratvold, J.D. Fox, M. Pybus, J.K. Preksaitis, and P. Tilley (2005). West Nile virus infection and conjunctival exposure. Emerging Infectious Diseases 11(10): 1648-1649. ISSN: 1080-6040.
Descriptors: bird diseases, conjunctiva, crows, occupational exposure, West Nile fever transmission, West Nile virus isolation and purification.
Gerhardt, R. (2006). West nile virus in the United States (1999-2005). Journal of the American Animal Hospital Association 42(3): 170-177.
Abstract: The accidental introduction of West Nile Virus into New York City from the Old World in 1999 resulted in an epidemic in humans, horses, and birds that swept to the west coast in just 3 years. The virus is transmitted by infective mosquitoes among susceptible native birds, which serve as amplifying hosts. Clinical disease occurs in humans and horses, but not enough virus is produced in their blood to infect other mosquitoes; therefore, humans and horses are considered dead-end hosts. Humans can best protect themselves by remaining indoors during periods of high mosquito activity and/or by using recommended repellents. Effective vaccines are available for horses.
Descriptors: West Nile virus, United States, virus transmission, mosquitoes, humans, birds, horses, dead end hosts.
Green, M.S., M. Weinberger, J. Ben Ezer, H. Bin, E. Mendelson, D. Gandacu, Z. Kaufman, R. Dichtiar, A. Sobel, D. Cohen, and M.Y. Chowers (2005). Long-term Death Rates, West Nile virus epidemic, Israel, 2000. Emerging Infectious Diseases 11(11): 1754-1757. ISSN: 1080-6040.
Abstract: We studied the 2-year death rate of 246 adults discharged from hospital after experiencing acute West Nile Virus infection in Israel during 2000. The age- and sex-adjusted death rates were significantly higher than in the general population. This excess was greater for men. Significant adverse prognostic factors were age, male sex, diabetes mellitus, and dementia.
Descriptors: communicable diseases, emerging mortality, disease outbreaks, West Nile fever mortality, aged humans, Israel, risk factors, survival rate, West Nile virus.
Hayes, E.B. and D.J. Gubler (2006). West Nile virus: Epidemiology and clinical features of an emerging epidemic in the United States. Annual Review of Medicine 57: 181-194. ISSN: 0066-4219.
Abstract: West Nile virus (WNV) was first detected in North America in 1999 during an outbreak of encephalitis in New York City. Since then the virus has spread across North America and into Canada, Latin America, and the Caribbean. The largest epidemics of neuroinvasive WNV disease ever reported occurred in the United States in 2002 and 2003. This paper reviews new information on the epidemiology and clinical aspects of WNV disease derived from greatly expanded surveillance and research on WNV during the past six years.
Descriptors: disease outbreaks, West Nile fever epidemiology, West Nile virus, United States.
Hayes, E.B., N. Komar, R.S. Nasci, S.P. Montgomery, D.R. O'Leary, and G.L. Campbell (2005). Epidemiology and transmission dynamics of West Nile virus disease. Emerging Infectious Diseases 11(8): 1167-1173. ISSN: 1080-6040.
Abstract: From 1937 until 1999, West Nile virus (WNV) garnered scant medical attention as the cause of febrile illness and sporadic encephalitis in parts of Africa, Asia, and Europe. After the surprising detection of WNV in New York City in 1999, the virus has spread dramatically westward across the United States, southward into Central America and the Caribbean, and northward into Canada, resulting in the largest epidemics of neuroinvasive WNV disease ever reported. From 1999 to 2004, >7,000 neuroinvasive WNV disease cases were reported in the United States. In 2002, WNV transmission through blood transfusion and organ transplantation was described for the first time, intrauterine transmission was first documented, and possible transmission through breastfeeding was reported. This review highlights new information regarding the epidemiology and dynamics of WNV transmission, providing a new platform for further research into preventing and controlling WNV disease.
Descriptors: disease outbreaks, insect vectors, West Nile fever epidemiology, West Nile virus growth and development, humans, United States.
Hayes, E.B., J.J. Sejvar, S.R. Zaki, R.S. Lanciotti, A.V. Bode, and G.L. Campbell (2005). Virology, pathology, and clinical manifestations of West Nile virus disease. Emerging Infectious Diseases 11(8): 1174-1179. ISSN: 1080-6040.
Abstract: West Nile virus (WNV) causes epidemics of febrile illness, meningitis, encephalitis, and flaccid paralysis. Since it was first detected in New York City in 1999, and through 2004, >16,000 WNV disease cases have been reported in the United States. Over the past 5 years, research on WNV disease has expanded rapidly. This review highlights new information regarding the virology, clinical manifestations, and pathology of WNV disease, which will provide a new platform for further research into diagnosis, treatment, and possible prevention of WNV through vaccination.
Descriptors: West Nile fever pathology, West Nile virus growth and development, antiviral agents, viral vaccines.
Hodge, J.G.J. and J.P. O'Connell (2005). West Nile virus: Legal responses that further environmental health. Journal of Environmental Health 68(1): 44-47.
Descriptors: environmental health, mosquito control, West Nile fever prevention and control, birds, consumer participation, health education, insecticides, New York City, risk assessment, United States.
Holcomb, S.S. (2005). Guidelines for West Nile virus. Nurse Practitioner 30(9): 7, 11, 14.
Descriptors: communicable diseases, emerging diseases diagnosis, practice guidelines, West Nile fever diagnosis, West Nile fever prevention and control, health education, mosquito control, population surveillance methods, primary prevention methods, risk factors, United States, West Nile virus.
Jamieson, D.J., D.B. Jernigan, J.E. Ellis, and T.A. Treadwell (2005). Emerging infections and pregnancy: West Nile virus, monkeypox, severe acute respiratory syndrome, and bioterrorism. Clinics in Perinatology 32(3): 765-776.
Abstract: As new infectious diseases, such as West Nile virus, monkeypox, and severe acute respiratory syndrome (SARS) are recognized in the United States, there are critical questions about how these infectious diseases will affect pregnant women and their infants. In addition, the implications of bioterrorist attacks for exposed pregnant women need to be considered. In this article, the authors address the following questions for a number of infectious disease threats: (1) does pregnancy affect the clinical course of these novel infectious diseases?, (2) what are the implications for prophylaxis and treatment of exposed or infected pregnant women, and (3) are these novel infectious diseases transmitted during pregnancy, labor and delivery, or breastfeeding?
Descriptors: bioterrorism, emerging communicable diseases, monkeypox, pregnancy complications, infectious diseases, severe acute respiratory syndrome (SARS), West Nile virus, smallpox, West Nile fever epidemiology.
Jester, P.M., S.J. Tilden, Y. Li, R.J. Whitley, and W.M. Sullender (2006). Regulatory challenges: Lessons from recent West Nile virus trials in the United States. Contemporary Clinical Trials 27(3): 254-259.
Abstract: Delays in research on emerging infections could deprive the public of appropriate therapies. This report describes challenges encountered in implementing two multicenter protocols of West Nile virus (WNV) infections in the United States during 2003. Protocol development times, federal regulatory approvals, and local Institutional Review Boards (IRB) approvals were compiled. Twenty eight institutions participated in a natural history study and 27 in a therapeutic trial of WNV developed through the National Institute of Allergy and Infectious Disease Collaborative Antiviral Study Group (CASG). The CASG compiled protocol development times, federal regulatory approvals, and local IRB approvals. Additional information on the local IRB process was obtained by survey of the investigators. Because of the lengthy development and approval process, protocols were distributed after the start of the epidemic season, most sites were unable to enroll subjects at the peak of the season, and a number of sites lacked IRB approval at the end of the season.
Descriptors: clinical trials standards, West Nile fever prevention and control, clinical trials methods, disease progression, ethics committees, multicenter studies, seasons, time factors, United States, epidemiology.
Johnson, G.D., M. Eidson, K. Schmit, A. Ellis, and M. Kulldorff (2006). Geographic prediction of human onset of West Nile virus using dead crow clusters: An evaluation of year 2002 data in New York State. American Journal of Epidemiology 163(2): 171-180.
Abstract: The risk of becoming a West Nile virus case in New York State, excluding New York City, was evaluated for persons whose town of residence was proximal to spatial clusters of dead American crows (Corvus brachyrhynchos). Weekly clusters were delineated for June-October 2002 by using both the binomial spatial scan statistic and kernel density smoothing. The relative risk of a human case was estimated for different spatial-temporal exposure definitions after adjusting for population density and age distribution using Poisson regression, adjusting for week and geographic region, and conducting Cox proportional hazards modeling, where the week that a human case was identified was treated as the failure time and baseline hazard was stratified by region. The risk of becoming a West Nile virus case was positively associated with living in towns proximal to dead crow clusters. The highest risk was consistently for towns associated with a cluster in the current or prior 1-2 weeks. Weaker, but positive associations were found for towns associated with a cluster in just the 1-2 prior weeks, indicating an ability to predict onset in a timely fashion.
Descriptors: bird diseases, epidemiology, crows, West Nile fever, cluster analysis, disease reservoirs, New York, population surveillance, proportional hazards models, West Nile virus isolation and purification.
Kilpatrick, A.M., L.D. Kramer, M.J. Jones, P.P. Marra, and P. Daszak (2006). West Nile virus epidemics in North America are driven by shifts in mosquito feeding behavior. PLoS Biology 4(4): E82.
Abstract: West Nile virus (WNV) has caused repeated large-scale human epidemics in North America since it was first detected in 1999 and is now the dominant vector-borne disease in this continent. Understanding the factors that determine the intensity of the spillover of this zoonotic pathogen from birds to humans (via mosquitoes) is a prerequisite for predicting and preventing human epidemics. We integrated mosquito feeding behavior with data on the population dynamics and WNV epidemiology of mosquitoes, birds, and humans. We show that Culex pipiens, the dominant enzootic (bird-to-bird) and bridge (bird-to-human) vector of WNV in urbanized areas in the northeast and north-central United States, shifted its feeding preferences from birds to humans by 7-fold during late summer and early fall, coinciding with the dispersal of its preferred host (American robins, Turdus migratorius) and the rise in human WNV infections. We also show that feeding shifts in Cx. tarsalis amplify human WNV epidemics in Colorado and California and occur during periods of robin dispersal and migration. Our results provide a direct explanation for the timing and intensity of human WNV epidemics. Shifts in feeding from competent avian hosts early in an epidemic to incompetent humans after mosquito infection prevalences are high result in synergistic effects that greatly amplify the number of human infections of this and other pathogens. Our results underscore the dramatic effects of vector behavior in driving the transmission of zoonotic pathogens to humans.
Descriptors: West Nile virus, vector-borne diseases, mosquito hosts, Culex pipens, feeding preferences of mosquitos, birds to human shift in preference, seasonal shift, WNV epidemics.
Kipp, A.M., J.A. Lehman, R.A. Bowen, P.E. Fox, M.R. Stephens, K. Klenk, N. Komar, and M.L. Bunning (2006). West Nile virus quantification in feces of experimentally infected American and fish crows. American Journal of Tropical Medicine and Hygiene 75(4): 688-690. ISSN: 0002-9637.
Abstract: To better understand the potential environmental health risk presented by West Nile virus (WNV)-contaminated feces, we quantified the amount of WNV present in the feces of experimentally infected American crows (Corvus brachyrhynchos) and fish crows (Corvus ossifragus). Peak fecal titers ranged from 10(3.5) to 10(8.8) plaque-forming units (PFU)/g for 10 American crows and from 10(2.3) to 10(6.4) PFU/g for 10 fish crows. The presence of infectious WNV in bird feces indicates a potential for direct transmission of WNV. Thus, handlers of sick or dead birds should take appropriate precautions to avoid exposure to fecal material.
Descriptors: bird diseases, crows, feces, virus shedding, West Nile fever, West Nile virus isolation and purification.
Kleinman, S., S.A. Glynn, M. Busch, D. Todd, L. Powell, L. Pietrelli, G. Nemo, G. Schreiber, C. Bianco, and L. Katz (2005). The 2003 West Nile virus United States epidemic: The America's Blood Centers experience. Transfusion 45(4): 469-479. ISSN: 0041-1132.
Descriptors: West Nile virus, disease epidemics, blood centers, viraemia, nucleic acid amplification technology, RNA, polymerase chain reaction, viral disease testing, detection, surveillance.
Komar, N. and G.G. Clark (2006). West Nile virus activity in Latin America and the Caribbean. Pan American Journal of Public Health 19(2): 112-117. ISSN: 1020-4989.
Descriptors: West Nile virus, Caribbean, Latin America, disease detection and transmission, birds, humans, horses, chickens.
Language of Text: Spanish.
Kondo, T. (2005). West Nile virus infection in horses. Journal of Veterinary Medicine 58(2): 135-138. ISSN: 0447-0192.
Descriptors: West Nile virus, horses, viral infection, epidemiology, zoonoses.
Language of Text: Japanese.
Kondro, W. (2006). West Nile virus still a threat. Canadian Medical Association Journal 175(6): 570.
Descriptors: West Nile fever, Canada, incidence, West Nile fever transmission.
Korves, C.T., S.J. Goldie, and M.B. Murray (2006). Blood screening for west nile virus: the cost-effectiveness of a real-time, trigger-based strategy. Clinical Infectious Diseases 43(4): 490-493.
Abstract: Previous studies have demonstrated that universal blood screening for West Nile virus is not cost-effective. A newly proposed, real-time, trigger-based screening strategy was analyzed and was also shown to be not cost-effective. These results were highly sensitive to pricing of screening assays.
Descriptors: mass screening economics, West Nile fever diagnosis, West Nile virus isolation and purification, cost-benefit analysis.
Lefrancois, T., B.J. Blitvich, J. Pradel, S. Molia, N. Vachiery, G. Pallavicini, N.L. Marlenee, S. Zientara, M. Petitclerc, and D. Martinez (2005). West Nile virus surveillance, Guadeloupe, 2003-2004. Emerging Infectious Diseases 11(7): 1100-1103. ISSN: 1080-6040.
Descriptors: West Nile virus surveillance, antibodies, Guadeloupe, epidemiology, poultry, seroprevalence, donkeys, fowls, horses.
Lim ChangKweng and I. Kurane (2005). The spread and resurgence of West Nile virus disease: Recent developments in the virology, epidemiology, and clinical characteristics. Yamaguchi Journal of Veterinary Medicine(32): 1-12. ISSN: 0388-9335.
Descriptors: West Nile virus, epidemiology, clinical characteristics, birds, literature review, virology, pathology, prevention.
Language of Text: Japanese; Summary in English.
Loeb, M., S.J. Elliott, B. Gibson, M. Fearon, R. Nosal, M. Drebot, C. D'Cuhna, D. Harrington, S. Smith, P. George, and J. Eyles (2005). Protective behavior and West Nile virus risk. Emerging Infectious Diseases 11(9): 1433-1436. ISSN: 1080-6040.
Descriptors: West Nile virus, protective behavior traits, survey, human disease outbreaks, reduced infection risk .
MacDonald, R.D. and V.F. Krym (2005). West Nile virus. Primer for family physicians. Canadian Family Physician Medecin De Famille Canadien 51: 833-837. ISSN: 0008-350X .
Abstract: OBJECTIVE: To provide primary care physicians with an understanding of West Nile virus in North America. This article focuses on epidemiology, clinical features, diagnosis, and prevention of infection. QUALITY OF EVIDENCE: MEDLINE and EMBASE searches revealed epidemiologic, surveillance, cohort, and outcome studies providing level II evidence. There were no randomized controlled trials of treatment. Recommended prevention and treatment strategies are based on level II and III evidence. MAIN MESSAGE: The mosquito-borne virus that first appeared on this continent in 1999 is now prevalent throughout North America. Most infections are asymptomatic. Fewer than 1% of those infected develop severe illness; 3% to 15% of those with severe illness die. While methods for controlling the mosquito population are available, we lack evidence that they reduce infection in the general human population. Family physicians have an important role in advising their patients on ways to prevent infection and in identifying patients who might be infected with West Nile virus. CONCLUSION: The general population is at low risk of West Nile virus infection. Prevention of infection rests on controlling the mosquito population and educating people on how to protect themselves against mosquito bites.
Descriptors: West Nile fever, prevention and control, family practice, disease diagnosis.
Mattar, S., E. Edwards, J. Laguado, M. Gonzalez, J. Alvarez, and N. Komar (2005). West Nile virus antibodies in Colombian horses. Emerging Infectious Diseases 11(9): 1497-1498. ISSN: 1080-6040 .
Descriptors: viral blood antibodies, emerging communicable diseases, flavivirus, West Nile virus, Colombia, hemolytic plaque technique, horses.
Mazurek, J.M., K. Winpisinger, B.J. Mattson, R. Duffy, and R.L. Moolenaar (2005). The epidemiology and early clinical features of West Nile virus infection. American Journal of Emergency Medicine 23(4): 536-543.
Abstract: We studied early clinical features of the West Nile virus (WNV) infection. Case patients were Ohio residents who reported to the Ohio Department of Health from August 14 to December 31, 2002, with a positive serum or cerebrospinal fluid for anti-WNV IgM. Of 441 WNV cases, medical records of 224 (85.5%) hospitalized patients were available for review. Most frequent symptoms were fever at a temperature of 38.0 degrees C or higher (n = 155; 69.2%), headache (n = 114; 50.9%), and mental status changes (n = 113; 50.4%). At least one neurological symptom, one gastrointestinal symptom, and one respiratory symptom was present in 186 (83.0%), 119 (53.1%), and 46 (20.5%) patients, respectively. Using multivariate logistic regression and controlling for age, we found that the initial diagnosis of encephalitis (P = .001) or reporting abdominal pain (P < .001) was associated with death. Because initial symptoms of WNV infection are not specific, physicians should maintain a high index of suspicion during the epidemic season, particularly in elderly patients with compatible symptoms.
Descriptors: West Nile fever, hospital statistics, numerical data, encephalitis, guillain barre syndrome, meningitis, Ohio, health care, humans.
Michaels, S.R., G.A. Balsamo, M. Kukreja, C. Anderson, S. Straif Bourgeois, G. Talati, and R.C. Ratard (2005). Surveillance for West Nile virus cases in Louisiana 2001-2004. Journal of the Louisiana State Medical Society Official Organ of the Louisiana State Medical Society 157(5): 269-272.
Abstract: West Nile virus (WNV) was first detected in Louisiana during August of 2001. An outbreak of 204 human cases of neuro-invasive disease (NID) and 25 deaths occurred in 2002. In the 2 years following, lower numbers of human cases were identified (101 NID cases in 2003 and 84 in 2004) but intense localized foci were observed. The incidence of NID has been particularly high in the elderly (65 years and older). The distribution of West Nile cases has consisted of sporadic cases with a few very intense foci. Annually, human cases have occurred from June through December, with a peak number of new cases in August. As compared with other WNV serosurveys conducted in the United States, it appears that the WNV seroprevalence in Louisiana is not elevated.
Descriptors: West Nile fever, humans, Louisiana, population surveillance, seroepidemiologic studies, survival rate.
Michaelson, P.G. and E.A. Mair (2005). West Nile virus: A primer for the otolaryngologist. Otolaryngology - Head and Neck Surgery 132(3): 347-352.
Abstract: BACKGROUND: Since recognition in the United States with a 1999 New York City epidemic, West Nile virus has enduringly migrated westward, leaving few states unaffected. Infection rates are rising at an alarming rate, doubling every year since introduction, with more than 9800 cases in 2003 alone and more than 260 deaths. Patients may present with myriad symptoms including a maculopapular rash that affects the face and trunk and diffuse lymphadenopathy, both of which may result in the initial consultation of the otolaryngologist. We review the clinical history of West Nile virus and its epidemiology, laboratory findings, and variable clinical presentation, with an emphasis on otolaryngologic manifestations. STUDY DESIGN AND SETTING COMPREHENSIVE: review of the literature over the past 50 years with an emphasis on what the present-day otolaryngologist needs to know concerning West Nile virus. Clinical manifestations of the head and neck such as encephalitis, meningitis, maculopapular rash, lymphadenopathy and dysphagia are discussed. RESULTS: To date, there are no articles in the otolaryngology literature discussing West Nile virus. These patients may present initially to multiple providers in diverse specialties because of multifarious initial signs and symptoms. The otolaryngologist must be educated on this quickly growing affliction and practice with a high index of suspicion. CONCLUSIONS: In this article we describe the clinical manifestations of West Nile virus, with an emphasis on the otolaryngologic manifestations. The otolaryngologist must become educated about this entity to facilitate preventative measures, adequately treat, and assist other providers in hopeful control and potential eradication of this infectious threat.
Descriptors: West Nile fever diagnosis, West Nile fever epidemiology, otolaryngology.
Montgomery, S.P., J.A. Brown, M. Kuehnert, T.L. Smith, N. Crall, R.S. Lanciotti, A. Macedo de Oliveira, T. Boo, and A.A. Marfin (2006). Transfusion-associated transmission of West Nile virus, United States 2003 through 2005. Transfusion 46(12): 2038-2046.
Abstract: BACKGROUND: National blood donation screening for West Nile virus (WNV) started in June 2003, after the documentation of WNV transfusion-associated transmission (TAT) in 2002. STUDY DESIGN AND METHODS: Blood donations were screened with investigational nucleic acid amplification assays in minipool formats. Blood collection agencies (BCAs) reported screening results to state and local public health authorities. Donor test results and demographic information were forwarded to CDC via ArboNET, the national electronic arbovirus surveillance system. State health departments and BCAs also reported suspect WNV TATs to CDC, which investigated these reports to confirm WNV infection in blood transfusion recipients in the absence of likely mosquito exposure. RESULTS: During 2003 to 2005, a total of 1,425 presumptive viremic donors were reported to CDC from 41 states. Of 36 investigations of suspected WNV TAT in 2003, 6 cases were documented. Estimated viremia levels were available for donations implicated in four TAT cases; the median estimated viremia was 0.1 plaque-forming units (PFUs) per mL (range, 0.06-0.50 PFU/mL; 1 PFU equals approximately 400 copies/mL). CONCLUSIONS: National blood screening for WNV identified and removed more than 1,400 potentially infectious blood donations in 2003 through 2005. Despite the success of screening in 2003, some residual WNV TAT risk remained due to donations containing very low levels of virus. Screening algorithms employing selected individual-donation testing were designed to address this residual risk and were fully implemented in 2004 and 2005. Continued vigilance for TAT will evaluate the effectiveness of these strategies.
Descriptors: blood donation, West Nile virus, transfusion transmission, blood collection, viremic donors, surveillance system, screening.
Morales, M.A., M. Barrandeguy, C. Fabbri, J.B. Garcia, A. Vissani, K. Trono, G. Gutierrez, S. Pigretti, H. Menchaca, N. Garrido, N. Taylor, F. Fernandez, S. Levis, and D. Enria (2006). West Nile virus isolation from equines in Argentina, 2006. Emerging Infectious Diseases 12(10): 1559-1561. ISSN: 1080-6040 .
Abstract: West Nile virus (WNV) was isolated from the brains of 3 horses that died from encephalitis in February 2006. The horses were from different farms in central Argentina and had not traveled outside the country. This is the first isolation of WNV in South America.
Descriptors: West Nile virus, horses, encephalitis, South America, Argentina, virus isolation.
Murray, K., S. Baraniuk, M. Resnick, R. Arafat, C. Kilborn, K. Cain, R. Shallenberger, T.L. York, D. Martinez, J.S. Hellums, D. Hellums, M. Malkoff, N. Elgawley, W. McNeely, S.A. Khuwaja, and R.B. Tesh (2006). Risk factors for encephalitis and death from West Nile virus infection. Epidemiology and Infection 134(6): 1325-1332.
Abstract: We conducted a nested case-control study to determine potential risk factors for developing encephalitis from West Nile virus (WNV) infection. Retrospective medical chart reviews were completed for 172 confirmed WNV cases hospitalized in Houston between 2002 and 2004. Of these cases, 113 had encephalitis, including 17 deaths, 47 had meningitis, and 12 were fever cases; 67% were male. Homeless patients were more likely to be hospitalized from WNV compared to the general population. A multiple logistic regression model identified age [odds ratio (OR) 1.1, P<0.001], history of hypertension, including those cases taking hypertension-inducing drugs (OR 2.9, P=0.012), and history of cardiovascular disease (OR 3.5, P=0.061) as independent risk factors for developing encephalitis from WNV infection. After adjusting for age, race/ethnicity (being black) (OR 12.0, P<0.001), chronic renal disease (OR 10.6, P<0.001), hepatitis C virus (OR 23.1, P=0.0013), and immunosuppression (OR 3.9, P=0.033) were identified as risk factors for death from WNV infection.
Descriptors: West Nile virus, risk factors, encephalitis control study, fever, meningitis, age, immunosuppression.
Murray, S. and E. Weir (2005). West Nile virus. Canadian Medical Association Journal 173(5): 484.
Descriptors: West Nile fever diagnosis, West Nile virus, diagnosis, insect bites and stings, insecticides, mosquito control, risk factors.
Orme Zavaleta, J., J. Jorgensen, B. D'Ambrosio, E. Altendorf, and P.A. Rossignol (2006). Discovering spatio-temporal models of the spread of West Nile virus. Risk Analysis 26(2): 413-422.
Abstract: Emerging infectious diseases are characterized by complex interactions among disease agents, vectors, wildlife, humans, and the environment. Since the appearance of West Nile virus (WNV) in New York City in 1999, it has infected over 8,000 people in the United States, resulting in several hundred deaths in 46 contiguous states. The virus is transmitted by mosquitoes and maintained in various bird reservoir hosts. Its unexpected introduction, high morbidity, and rapid spread have left public health agencies facing severe time constraints in a theory-poor environment, dependent largely on observational data collected by independent survey efforts and much uncertainty. Current knowledge may be expressed as a priori constraints on models learned from data. Accordingly, we applied a Bayesian probabilistic relational approach to generate spatially and temporally linked models from heterogeneous data sources. Using data collected from multiple independent sources in Maryland, we discovered the integrated context in which infected birds are plausible indicators for positive mosquito pools and human cases for 2001 and 2002.
Descriptors: biological models, West Nile fever transmission, Bayesian theorem, birds, disease outbreaks, disease reservoirs, Maryland epidemiology, risk, West Nile virus isolation and purification.
Overstreet, M. (2005). Patient education series. West Nile virus. Nursing 35(8): 64.
Descriptors: West Nile fever diagnosis, West Nile fever therapy, West Nile fever transmission, West Nile virus.
Ozer, N. (2006). Bati Nil virusu ve vektorleri. [West Nile virus and its vectors]. Mikrobiyoloji Bulteni 40(1-2): 121-128.
Abstract: There are more than five hundred known arthropod-borne viruses (arboviruses) all around the world and approximately hundred of them may cause disease in humans. During the past 20 years there has been a dramatic resurgence or emergence of epidemic arboviral diseases affecting both humans and domestic animals. Many factors play important roles in the emergence of arboviral diseases like Yellow Fever, Dengue, West Nile encephalitis, and of other diseases such as malaria and leishmaniasis in countries where they have not been previously encountered and in the increase in incidences where they have been under control. Some of these are demographic factors such as global population increase and uncontrolled urbanization; social changes such as modern transportation, human encroachment on natural disease hotspots; changes in agricultural activities such as the use of new irrigation techniques; deforestation; genetic changes in the pathogens; preventive measures and probably global climate changes. Mosquitoes are among the most important vectors carrying viruses belonging to Alphavirus, Flavivirus, Bunyavirus and Phlebovirus genera. All of the above factors have contributed to the increase in mosquito populations and closer contact between humans and mosquito vectors. West Nile virus notable after the epidemic of 1996 in Romania in Europe is one of the latest examples indicating that viruses can jump continents and produce epidemics. In this review article, the distribution of West Nile virus and its principal vectors and also its importance by means of public health, have been discussed.
Descriptors: West Nile virus, arthropod-borne arboviruses, mosquito populations, literature review.
Language of Text: Turkish.
Paddock, C.D., W.L. Nicholson, J. Bhatnagar, C.S. Goldsmith, P.W. Greer, E.B. Hayes, J.A. Risko, C. Henderson, C.G. Blackmore, R.S. Lanciotti, G.L. Campbell, and S.R. Zaki (2006). Fatal hemorrhagic fever caused by West Nile virus in the United States. Clinical Infectious Diseases an Official Publication of the Infectious Diseases Society of America 42(11): 1527-1535.
Abstract: BACKGROUND: Most West Nile virus (WNV) infections in humans are asymptomatic; severe disease occurs in relatively few patients and typically manifests as encephalitis, meningitis, or acute flaccid paralysis. A few cases of life-threatening disease with diffuse hemorrhagic manifestations have been reported in Africa; however, this clinical presentation has not been documented for any of the >16,700 cases of WNV disease reported in the United States during 1999-2004. We describe a case of fulminant WNV infection in a 59-year-old Florida man who died following a brief illness that resembled hemorrhagic disease caused by Rickettsia reckettsii, dengue virus or yellow fever virus. METHODS: Traditional and contemporary diagnostic assays, including culture isolation, electron microscopic examination, reverse-transcriptase polymerase chain reaction amplification, and immunohistochemical stains, were used to confirm systemic WNV infection in the patient. RESULTS: WNV was isolated in a cell culture from a skin biopsy specimen obtained from the patient shortly prior to death. Electron microscopic examination identified the isolate as a flavivirus, and reverse-transcriptase polymerase chain reaction amplified specific WNV sequences from the isolate and patient tissue. Quantitative polymerase chain reaction identified approximately 1x10(7) viral copies/mL in the patient's serum. WNV antigens were detected by immunohistochemical stains in intravascular mononuclear cells and endothelium in skin, lung, liver, kidney, spleen, bone marrow, and central nervous system; no viral antigens were identified in neurons or glial cells of the central nervous system. CONCLUSIONS: Although hemorrhagic disease is a rare manifestation of WNV infection, the findings provided by this report may offer new insights regarding the clinical spectrum and pathogenesis of WNV disease in humans.
Descriptors: hemorrhagic fevers, viral virology, West Nile Virus fever, fatal outcome, hemorrhagic fevers, viral epidemiology, skin pathology, United States.
Patnaik, J.L., H. Harmon, and R.L. Vogt (2006). Follow-up of 2003 human West Nile virus infections, Denver, Colorado. Emerging Infectious Diseases 12(7): 1129-1131. ISSN: 1080-6040 .
Abstract: Tri-County Health Department and Boulder County Public Health conducted a follow-up study of all nonfatal West Nile virus (WNV) cases reported during 2003 in 4 metropolitan Denver, Colorado, counties. Self-reported patient information was obtained approximately 6 months after onset. A total of 656 (81.2%) eligible WNV patients are included in this study.
Descriptors: West Nile fever, epidemiology, Colorado, middle aged humans, odds ratio, risk factors.
Paz, S. (2006). The West Nile Virus outbreak in Israel (2000) from a new perspective: The regional impact of climate change. International Journal of Environmental Health Research 16(1): 1-13.
Abstract: The West Nile Virus (WNV) outbreak in Israel in 2000 appeared after medical and climatic warning signs. Re-analysis of the epidemic from a new viewpoint, the regional impact of global warming, especially the worsening in the summers' heat conditions, is presented. The disease appeared averagely at a lag of 3-9 weeks (strongest correlation = lag of 7 weeks). The minimum temperature was found as the most important climatic factor that encourages the disease earlier appearance. Extreme heat is more significant than high air humidity for increasing WNV cases. An early extreme rise in the summer temperature could be a good indicator of increased vector populations. While 93.5% of cases were in the metropolitan areas, the disease was not reported in the sub-arid regions. The outbreak development was comparable to the cases from Romania (1996) and NYC (1999). Each of those epidemics appeared after a long heatwave.
Descriptors: disease outbreaks, disease vectors, West Nile fever epidemiology, West Nile virus, climate, humidity, Israel epidemiology, seasons, temperature, time factors, urban population.
Petropoulou, K.A., S.M. Gordon, R.A. Prayson, and P.M. Ruggierri (2005). West Nile virus meningoencephalitis: MR imaging findings. American Journal of Neuroradiology 26(8): 1986-1995.
Abstract: BACKGROUND AND PURPOSE: Reports of MR imaging in West Nile virus (WNV) meningoencephalomyelitis are few and the described findings limited. The purpose of this study was to review the spectrum of MR imaging findings for WNV meningoencephalomyelitis and investigate whether any of the findings correlates with clinical presentation of flaccid paralysis. METHODS: We reviewed the MR imaging findings of 17 patients with confirmed WNV encephalitis and/or myelitis. MR imaging brain studies were evaluated for location of signal intensity abnormalities, edema, hydrocephalus, or abnormal enhancement. MR imaging spine studies were evaluated for signal intensity abnormalities in cord and/or enhancement. RESULTS: Retrospective review of the MR imaging studies of 17 patients was performed by 2 neuroradiologists. Eleven of 16 brain MR images demonstrated abnormalities. Eight (50%) patients had abnormal studies related to meningoencephalitis. All 8 patients had abnormal findings in the deep gray matter and/or brain stem; 2 had additional white matter abnormalities. Three patients with abnormal MR studies of the spine had extremity weakness on examination. The imaging findings included abnormal signal intensity more pronounced in the ventral horns and/or enhancement around the conus medullaris and cauda equina. One patient had additional abnormalities in the pons. CONCLUSION: Abnormal MR imaging findings in patients with WNV meningoencephalomyelitis are nonspecific but not uncommon. Anatomic areas commonly affected are basal ganglia, thalami, mesial temporal structures, brain stem, and cerebellum. Extremity weakness or flaccid paralysis corresponds to spinal cord/cauda equina abnormalities.
Descriptors: magnetic resonance imaging, meningoencephalitis, West Nile fever, brain pathology, extremities, muscle weakness, paraplegia, retrospective studies, spinal cord, humans.
Pfleiderer, C., C. Koenig, M. Chudy, M. Schmidt, W.K. Roth, E. Seifried, and C.M. Nuebling (2005). Prevalence of West Nile virus in central Europe. Vox Sanguinis 89(Suppl. 1): 103. ISSN: 0042-9007.
Descriptors: West Nile virus prevalence, central Europe, epidemiology.
Notes: Meeting Information: 15th Regional Congress of the International Society of Blood Transfusion, Europe, Athens, Greece; July 2-6, 2005.
Pfleiderer, C., C. Konig, M. Chudy, M. Schmidt, W.K. Roth, and C.M. Nubling (2006). Molecular epidemiology of West Nile Virus in humans. Developments in Biologicals 126: 197-201; Discussion 326-327.
Abstract: After the introduction of West Nile Virus into the United States of America in 1999 followed by annual WNV epidemics during the mosquito seasons and spreading of the virus from the East (New York; 1999) to the West of the U.S. (California; 2003/2004) there appeared the question of whether a similar scenario could happen in Europe, too. To be able to answer this question the German Ministry of Health decided to investigate the prevalence and incidence of WNV infections in German blood donors. First a test algorithm was established taking into account the high level of cross-reactivity between different flavivirus infections in serological test systems. AntiWNV-suspicious specimens were further investigated for their neutralisation capacity and by an antiWNV confirmation assay developed in-house. As a preliminary result of our studies a very low prevalence of WNV infections in healthy German blood donors was measured. Development of highly specific test systems is necessary for accurate and reliable differential diagnosis of flavivirus infections.
Descriptors: West Nile fever, West Nile virus isolation and purification, viral blood antibodies, Austria, epidemiology, blood donors, Germany.
Prince, H.E., L.H. Tobler, M. Lape Nixon, G.A. Foster, S.L. Stramer, and M.P. Busch (2005). Development and Persistence of West Nile Virus-Specific Immunoglobulin M (IgM), IgA, and IgG in Viremic Blood Donors. Journal of Clinical Microbiology. 43(9): 4316-20. ISSN: 0095-1137.
Abstract: West Nile Virus (WNV) antibody development and persistence were investigated in blood donors who made WNV RNA-positive (viremic) donations in 2003. Plasma samples from the index donations and follow-up serum or plasma samples were tested for WNV immunoglobulin M (IgM), IgA, and IgG by using enzyme-linked immunosorbent assays. Antibody development was investigated with 154 samples collected from 84 donors 1 to 21 days after their RNA-positive, antibody-negative, index donation. WNV IgM and IgA were first detected on day 3, and all samples collected after day 9 were WNV IgM and IgA positive; WNV IgG was first detected on day 4, and all samples collected after day 16 were positive. Antibody persistence in this donor group (index donations antibody negative) was evaluated by using 128 samples collected from 89 donors on days 22 to 440 of follow-up; 88% of samples were WNV IgM positive, 86% were WNV IgA positive, and 100% were WNV IgG positive. In linear regression analysis, trendlines for WNV IgM and IgA reached the value discriminating positive from negative results at 218 days and 232 days of follow-up, respectively. Similar WNV IgM and IgA persistence trends characterized 27 donors whose index samples were positive for WNV IgM and IgA, as well as 14 donors whose index samples were positive for WNV IgG but negative for WNV IgM. These findings show that WNV IgG emerges after WNV IgM and IgA and that both WNV IgM and IgA typically persist for at least 6 months after infection. Thus, unlike some other flavivirus infections, WNV infection is not characterized by a relatively rapid disappearance of virus-specific IgA.
Descriptors: West Nile virus, viremic blood donors, specific immunoglobulin M, IgM, persistence, plasma samples, enzyme linked immunosorbent assays.
Rao, N., D. Char, and S. Gnatz (2005). Rehabilitation outcomes of 5 patients with severe West Nile virus infection: A case series. Archives of Physical Medicine and Rehabilitation 86(3): 449-452. ISSN: 0003-9993.
Abstract: OBJECTIVE: To report inpatient rehabilitation outcome in severe cases of West Nile virus (WNV) infection. DESIGN: Retrospective case series. SETTING: Freestanding rehabilitation hospital. PARTICIPANTS: Five consecutive patients admitted to an inpatient rehabilitation hospital with proven WNV infection. PATIENTS: had severe neurologic manifestations and functional deficits. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: FIM instrument scores. RESULTS: On admission, overall FIM scores ranged from 31 to 68, with a mean of 44.40+/-15.85; overall FIM scores ranged from 52 to 90, with a mean of 76.00+/-15.03 at discharge. CONCLUSIONS: All patients demonstrated significant functional improvement ( P <.001). Length of stay ranged from 10 to 71 days, with a mean of 32 days. Lower functional outcome and higher cost of care were noted in patients and was attributable to severe muscle weakness and axonal neuropathy.
Descriptors: West Nile fever rehabilitation, comorbidity, hospitalization economics, rehabilitation centers, retrospective studies, treatment outcome.
Rappole, J.H., B.W. Compton, P. Leimgruber, J. Robertson, D.I. King, and S.C. Renner (2006). Modeling movement of West Nile virus in the Western hemisphere. Vector Borne and Zoonotic Diseases 6(2): 128-139. ISSN: 1530-3667.
Abstract: We modeled West Nile virus (WNV) movement rates and patterns based on a migratory bird agent (the Swainson's Thrush) and a resident bird agent (the House Sparrow), and compared the results of these models with actual movement data to investigate the likelihood that the pattern of WNV outbreaks observed in the New World was consistent with migrant bird-mediated spread, as reported from the Old World. We found that, contrary to Old World patterns, WNV activity in the Western Hemisphere does not seem consistent with movement by infected migrant birds. Instead WNV spread appears best explained by a non-directional movement, perhaps that of dispersing resident birds.
Descriptors: bird disease transmission, West Nile fever, disease outbreaks, biological models, North America, West Nile virus.
Rawal, A., P.J. Gavin, and C.D. Sturgis (2006). Cerebrospinal fluid cytology in seasonal epidemic West Nile virus meningo-encephalitis. Diagnostic Cytopathology 34(2): 127-129.
Abstract: The incidence of West Nile Virus (WNV) infection has progressively increased in North America since the first epidemic in 1999. Formal scholarly documentation of cerebrospinal fluid (CSF) cytology changes in patients with WNV infection is limited. We report our experience with CSF cytospins from a population of consecutive patients with documented CSF WNV-specific IgM. Thirty-two patients (12 male, 20 female) with a median age of 52 yr (range, 19-88) diagnosed with WNV meningo-encephalitis were studied. Symptoms were present for a mean of 5 days (range, 1-14) prior to lumbar puncture. CSF proteins were elevated in 94% of patients (30/32) with a mean value of 79 mg/dl (range, 36-185). CSF glucose was normal to elevated in all cases. All cytomorphologically adequate samples demonstrated a pleocytosis with a mean of 156 cells/mm3 (range, 13-683). Nearly, all (26/28) patients showed increased CSF neutrophils--mean 43% (range, 1-83). Mean lymphocyte and monocyte fractions were 44% (range, 8-85) and 14% (range, 2-27), respectively. Three cases showed 1-4% plasma cells. Mean total leukocyte counts (TLC) (197 cells/mm3) and mean neutrophil fractions (50%) were greater in patients sampled within the first 3 days of symptoms than in those sampled beyond day 3 (mean TLC, 126 cells/mm3; mean neutrophil fraction, 37%). Relative lymphocyte proportions increased from a mean of 39 to 48% after 3 days of illness. WNV should be considered as a potential etiology of infectious CSF pleocytosis in the North American late summer and early fall seasons. 2006 Wiley-Liss, Inc.
Descriptors: cerebrospinal fluid, meningoencephalitis, West Nile virus, immunoglobulin M metabolism, seasons, West Nile virus.
Redig, P., M. Saggese, T. Tully, A. Roy, B. Ritchie, and A. Allison (2005). Update on West Nile virus disease and vaccine. In: Small animal and exotics: Proceedings of the North American Veterinary Conference, January 8, 2005-January 12, 2005, Orlando, Florida, USA, Eastern States Veterinary Association: Gainesville, USA, Vol. 19, p. 1197-1198.
Descriptors: West Nile virus, virus disease, vaccines, updates.
Reds-Study-Grp (2005). Detection of West Nile virus RNA and antibody in frozen plasma components from a voluntary market withdrawal during the 2002 peak epidemic. Transfusion (Malden) 45(4): 480-486. ISSN: 0041-1132.
Descriptors: West Nile virus, frozen blood components, viremia, serologic markers, RNA, IgM, risk factors.
Rios, M., M.J. Zhang, A. Grinev, K. Srinivasan, S. Daniel, O. Wood, I.K. Hewlett, and A.I. Dayton (2006). Monocytes-macrophages are a potential target in human infection with West Nile virus through blood transfusion. Transfusion 46(4): 659-667.
Abstract: BACKGROUND: West Nile virus (WNV) transmission by transfusion was documented in 2002. Approximately 80 percent of WNV infections are asymptomatic and 1 percent develop severe neurological illness. In animals, Langerhans-dendritic cells support initial viral replication, followed by replication in lymphoid tissues and dissemination to organs and possibly to the CNS. The cellular tropism of WNV infection after transfusion and the particular human blood cells that sustain viral replication remain largely unknown. Whether primary monocyte-derived macrophages (MDMs) support WNV infection-replication and produce infectious virions, with an in vitro system, was investigated. STUDY DESIGN AND METHODS: Elutriated monocytes (CD33+/CD14+) from suitable blood donors were cultured in the presence of macrophage-colony-stimulating factor, infected with WNV-NY99 at different time points, washed, and cultivated for up to 47 days. Supernatants were tested for WNV replication by TaqMan reverse transcription-polymerase chain reaction (RT-PCR), with primers for the envelope and/or 3'NC regions, and by cDNA-PCR to detect WNV minus-strand RNA and for the presence of functional virions by infectivity assays in Vero cells. RESULTS: RT-PCR TaqMan of supernatants demonstrated productive infection of MDMs. Viral load reached 2 to 5 log above baseline in 3 to 6 days and then declined, with detectable viral replication persisting for up to 47 days. WNV minus-strand RNA was detected in Day 4 cultures, indicating active viral replication. Infected MDM cultures showed no cytopathic changes. Supernatants that were TaqMan-positive for the presence of WNV-infected Vero cells and produced cytopathic effects within 3 to 5 days of culture. CONCLUSION: The susceptibility of monocytes-macrophages to productive infection in vitro is compatible with a potential role in initial WNV replication and propagation after transmission by transfusion.
Descriptors: blood transfusion, macrophages, monocytes, West Nile fever prevention and control, West Nile virus isolation and purification, cultured cells, reverse transcriptase polymerase chain reaction.
Samuel, M.A. and M.S. Diamond (2006). Pathogenesis of West Nile Virus infection: a balance between virulence, innate and adaptive immunity, and viral evasion. Journal of Virology 80(19): 9349-9360. ISSN: 0022-538X.
Descriptors: immunity, natural immunology, West Nile fever, West Nile virus, central nervous system, disease susceptibility.
Sanchez Guerrero, S.A., S. Romero Estrella, A. Rodriguez Ruiz, L. Infante Ramirez, A. Gomez, E. Villanueva Vidales, M. Garcia Torres, A.M. Dominguez, J.A. Vazquez, E.D. Calderon, L. Valiente Banuet, J.M. Linnen, A. Broulik, W. Harel, and R.A. Marin Y Lopez (2006). Detection of West Nile virus in the Mexican blood supply. Transfusion 46(1): 111-117.
Abstract: BACKGROUND: West Nile virus (WNV) is the etiologic agent of an emerging disease in the Western Hemisphere that can be transmitted to humans by blood transfusion. WNV first appeared in the United States in 1999, in Canada in 2001, and in Mexico in 2002. The aim of this nationwide study was to determine the prevalence of WNV in blood donors in Mexico as a first step in preventing its transfusion-associated transmission. STUDY DESIGN AND METHODS: In July and August 2004, a total of 3856 fresh plasma specimens collected from each state's center for blood transfusion in 29 of 31 Mexican states were screened with an investigational WNV assay (Procleix,(R) Gen-Probe Inc. and Chiron Corp.), a nucleic acid test based on transcription-mediated amplification (TMA). Reactive specimens were confirmed with a second TMA-based test, the alternative WNV assay (Gen-Probe), and with WNV capture enzyme-linked immunosorbent assays (ELISAs) for detection of immunoglobulin M (IgM) and IgG antibodies. In addition, 3714 frozen plasma samples collected in 2002 and 2003 were similarly tested. RESULTS: One of 3856 fresh samples from an asymptomatic donor from Chihuahua was reactive by both TMA-based tests and IgM ELISA, suggesting a recently acquired infection. The observed percentage of viremic donors blood donors was 0.03 percent. Results from frozen samples were not included in the prevalence calculation and none were TMA-reactive for WNV. CONCLUSIONS: WNV is present in the Mexican blood supply and measures should be taken to reduce the risk of transfusion transmission.
Descriptors: viral antibodies in blood, blood banks, blood donors, communicable diseases, West Nile fever, West Nile virus, blood transfusion, emerging diseases prevention and control, enzyme linked immunosorbent assay, Mexico, reverse transcriptase polymerase chain reaction.
Schweitzer, B.K., W.L. Kramer, A.R. Sambol, J.L. Meza, S.H. Hinrichs, and P.C. Iwen (2006). Geographic factors contributing to a high seroprevalence of West Nile virus-specific antibodies in humans following an epidemic. Clinical and Vaccine Immunology 13(3): 314-318. ISSN: 1556-6811.
Abstract: Sera of 624 blood donors were evaluated to determine seroprevalence of West Nile virus (WNV) antibodies following the 2003 WNV epidemic in Nebraska. Geographic factors contributing to differences in WNV seropositivity were evaluated. The overall prevalence of WNV in Nebraska was higher than reported previously in other U.S. locations (9.5% WNV immunoglobulin G seroprevalence rate), with the highest prevalence identified in the western part of the state (19.7%), followed by the central (13.8%) and the eastern (4.2%) parts. Regions of the state with the highest WNV-positive mosquito rates correlated with the highest human WNV seroprevalence rates. The results showed that both the western and central parts of the state, where mosquito positivity rates were highest, had significantly higher seroprevalence rates than the eastern region. Additional studies are needed to determine whether the high prevalence rates in Nebraska will be reflected in other states and what impact environmental and geographical factors may have on future outbreaks of WNV infection.
Descriptors: viral blood antibodies, disease outbreaks, West Nile fever, West Nile virus, Nebraska, seroepidemiologic studies.
Secko, D. (2005). Immunotherapy for West Nile virus infection. Canadian Medical Association Journal 173(6): 591.
Descriptors: monoclonal antibodies, immunotherapy trends, West Nile fever, West Nile virus, mice, survival analysis.
Skupski, D.W., G.S. Eglinton, A.D. Fine, E.B. Hayes, and D.R. O'Leary (2006). West Nile virus during pregnancy: A case study of early second trimester maternal infection. Fetal Diagnosis and Therapy 21(3): 293-295.
Abstract: A woman who contracted West Nile virus (WNV) neuroinvasive illness during her second trimester subsequently elected to terminate her pregnancy due to concerns of possible adverse effects of WNV on her developing fetus. Consent was obtained to test maternal and post-mortem fetal tissues for WNV infection. Fetal blood, liver, kidneys, spleen, umbilicus and amniotic fluid were negative for WNV RNA by polymerase chain reaction and negative for WNV IgM antibodies by ELISA, indicating that in this case there was no evidence of WNV transmission to the fetus. Until further information regarding outcomes of WNV infection during pregnancy is available, pregnant women in areas where WNV is transmitted should take precautions to avoid mosquito bites. Women with WNV illness during pregnancy should undergo regular prenatal checkups including ultrasound examinations to assess fetal development, and healthcare providers should promptly report cases of WNV in pregnant women to their state or local health department or to CDC. Copyright 2006 S. Karger AG, Basel.
Descriptors: pregnancy complications, West Nile fever, induced abortion, amniotic fluid, vertical disease transmission, fetal blood, gestational age, kidney, liver.
Teehee, M.L., M.L. Bunning, S. Stevens, and R.A. Bowen (2005). Experimental infection of pigs with West Nile virus. Archives of Virology 150(6): 1249-12. ISSN: 0304-8608.
Abstract: Young adult and weanling pigs were challenged with the New York 99 strain of West Nile virus through the bite of infected mosquitoes. Each of six adult pigs seroconverted, but virus was isolated from serum of only one pig following challenge. Three of five weanling pigs developed viremia, with peak titers of 10(1.9) and 10(3.1) PFU/mL. Clinical signs attributable to West Nile virus infection were not observed in any of these animals. An additional four pigs were challenged by feeding West Nile virus-infected mice, and none of the four developed a detectable viremia or seroconverted. These results suggest that pigs are unlikely to play a significant role as amplifying hosts of West Nile virus.
Descriptors: West Nile fever transmission, West Nile virus, infected mosquitoes, viral blood antibodies, mice, neutralization tests, swine, viremia.
Tiawsirisup, S., K.B. Platt, F. Fabiosa, and W.A. Rowley (2006). West Nile virus titers in Aedes vexans (Meigen) and Culex pipiens (L.) saliva. Thai Journal of Veterinary Medicine 36(1): 87. ISSN: 0125-6491.
Descriptors: West Nile virus titers, mosquito saliva, blood meals, virus isolation, titration plaque assay, Aedes vexans, Culex pipiens, birds.
Notes: Meeting Information: Proceedings of the Annual Conference of the Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand; April 27-28 , 2006.
Turell, M., D. Dohm, M. Sardelis, M. O' Guinn, T. Andreadis, and J. Blow (2005). An update on the potential of North American mosquitoes (Diptera: Culicidae) to transmit West Nile virus. Journal of Medical Entomology. 42(1): 57-62. ISSN: 0022-2585.
Abstract: Since first discovered in the New York City area in 1999, West Nile virus (WNV) has become established over much of the continental United States and has been responsible for >10,000 cases of severe disease and 400 human fatalities, as well as thousands of fatal infections in horses. To develop appropriate surveillance and control strategies, the identification of which mosquito species are competent vectors and how various factors influence their ability to transmit this virus must be determined. Therefore, we evaluated numerous mosquito species for their ability to transmit WNV under laboratory conditions. This report contains data for several mosquito species not reported previously, as well as a summary of transmission data compiled from previously reported studies. Mosquitoes were allowed to feed on chickens infected with WNV isolated from a crow that died during the 1999 outbreak in New York City. These mosquitoes were tested approximately equal to 2 wk later to determine infection, dissemination, and transmission rates. All Culex species tested were competent vectors in the laboratory and varied from highly efficient vectors (e.g., Culex tarsalis Coquillett) to moderately efficient ones (e.g., Culex nigripalpus Theobald). Nearly all of the Culex species tested could serve as efficient enzootic or amplifying vectors for WNV. Several container-breeding Aedes and Ochlerotatus species were highly efficient vectors under laboratory conditions, but because of their feeding preferences, would probably not be involved in the maintenance of WNV in nature. However, they would be potential bridge vectors between the avian-Culex cycle and mammalian hosts. In contrast, most of the surface pool-breeding Aedes and Ochlerotatus species tested were relatively inefficient vectors under laboratory conditions and would probably not play a significant role in transmitting WNV in nature. In determining the potential for a mosquito species to become involved in transmitting WNV, it is necessary to consider not only its laboratory vector competence but also its abundance, host-feeding preference, involvement with other viruses with similar transmission cycles, and whether WNV has been isolated from this species under natural conditions.
Descriptors: Culicidae, Culex, mosquitoes, insect vectors, West Nile virus, vector potential, vector competence, disease transmission, infection, vectorial capacity, infection-rate, dissemination-rate, transmission-rate.
Vamvakas, E.C., S. Kleinman, H. Hume, and G.D. Sher (2006). The development of West Nile virus safety policies by Canadian blood services: Guiding principles and a comparison between Canada and the United States. Transfusion Medicine Reviews 20(2): 97-109.
Abstract: To address the emerging threat of West Nile virus (WNV) to the blood supply, Canadian Blood Services (CBS) made a series of policy decisions that were either similar to those adopted in the United States or more stringent than policies formulated in the United States at the same time. More stringent Canadian policies included the development of an in-house WNV RNA assay, the stockpiling of frozen plasma components in the winter for transfusion in WNV-affected areas in the summer, a special recruitment campaign for red blood cell collections before the start of the 2003 WNV season, and an inventory exchange (ie, WNV-tested for untested red blood cells) initiated 2 weeks after the onset of WNV screening, as well as the implementation of targeted individual-donation WNV testing on August 2, 2004, in the absence of any positive donors or clinical cases of WNV infection in Canada. The general principles that guided CBS decision making with regard to WNV safety included application of the precautionary principle, harmonization with policies in the United States, a consideration of logistic issues, compliance with Health Canada requests, responsiveness to public expectations about transfusion safety, and transparency in decision making with timely communication to stakeholders. Before implementing WNV blood safety policies, CBS assessed their impact on blood availability. When policies were implemented, data were obtained quickly to ensure that the prior impact assessments were accurate. This review discusses the guiding principles affecting CBS policy development and compares CBS WNV safety policies to policies adopted in the United States.
Descriptors: blood bank standards, blood transfusion safety, West Nile fever prevention and control, West Nile virus, blood specimen collection standards, blood transfusion, Canada, health policy, United States.
van der Meulen, K.M., M.B. Pensaert, and H.J. Nauwynck (2005). West Nile virus in the vertebrate world. Archives of Virology 150(4): 637-657. ISSN: 0304-8608.
Abstract: West Nile virus (WNV), an arthropod-borne virus belonging to the family Flaviviridae, had been recognized in Africa, Asia and the south of Europe for many decades. Only recently, it has been associated with an increasing number of outbreaks of encephalitis in humans and equines as well as an increasing number of infections in vertebrates of a wide variety of species. In this article, the data available on the incidence of WNV in vertebrates are reviewed. Moreover, the role of vertebrates in the transmission of WNV, the control of WNV infections in veterinary medicine as well as future perspectives are discussed. A wide variety of vertebrates, including more than 150 bird species and at least 30 other vertebrate species, are susceptible to WNV infection. The outcome of infection depends on the species, the age of the animal, its immune status and the pathogenicity of the WNV isolate. WNV infection of various birds, especially passeriforms, but also of young chickens and domestic geese, results in high-titred viremia that allows arthropod-borne transmission. For other vertebrate species, only lemurs, lake frogs and hamsters develop suitable viremia levels to support arthropod-borne transmission. The role of vertebrates in direct, non-arthropod-borne transmission, such as via virus-contaminated organs, tissues or excretions is less well characterized. Even though direct transmission can occur among vertebrates of several species, data are lacking on the exact amounts of infectious virus needed. Finally, the increased importance of WNV infections has led to the development of killed, live-attenuated, DNA-recombinant and chimeric veterinary vaccines.
Descriptors: animal diseases, West Nile fever, horse diseases, horses.
van der Meulen, K.M., M.B. Pensaert, and H.J. Nauwynck (2005). West Nile virus in the vertebrate world. Archives of Virology 150(4): 637-657. ISSN: 0304-8608.
Descriptors: West Nile virus, vertebrates, disease transmission, encephalitis, species vectors, viremia, arthropods, vaccine development.
Ward, M.P. (2005). Epidemic West Nile virus encephalomyelitis: A temperature-dependent, spatial model of disease dynamics. Preventive Veterinary Medicine 71(3-4): 253-264.
Abstract: Since first being detected in New York in 1999, West Nile virus (WNV) has spread throughout the United States and more than 20,000 cases of equine WNV encephalomyelitis have been reported. A spatial model of disease occurrence was developed, using data from an outbreak of serologically confirmed disease in an unvaccinated population of horses at 108 locations in northern Indiana between 3 August and 17 October 2002. Daily maximum temperature data were recorded at meteorological stations surrounding the study area. The distribution of the total number of degree-days elapsing between July 4 and the date of diagnosis of each case was best described by a normal distribution (mean=5243 degrees F, S.D.=1047). The days on which the average risk was >25, >50 and >75% were predicted (versus observed) to occur on August 23 (August 9), August 31 (September 2) and September 9 (September 9). The epidemic was predicted to occur 3 days earlier, or 4 days later, than observed if temperatures in the study area were uniformly increased, or decreased, by 5 degrees F, respectively. Maps indicated that WNV encephalomyelitis risk always remained greater in the northwest quadrant of the study area. Since WNV might exist at a hypoendemic level of infection, and occasionally re-emerge as a cause of epidemics in equine populations, by identifying factors that contributed to this epidemic, the potential impact of future epidemics can be reduced. Such studies rely on a GIS framework, availability of meteorological and possibly remotely sensed data and information on host and landscape factors. An early-warning system for WNV transmission in equine populations could be developed.
Descriptors: animal disease outbreaks, horse diseases, West Nile fever, horses, Indiana, statistical models, space-time clustering, West Nile virus.
Ward, M.P., J.A. Schuermann, L.D. Highfield, and K.O. Murray (2006). Characteristics of an outbreak of West Nile virus encephalomyelitis in a previously uninfected population of horses. Veterinary Microbiology 118(3-4): 255-259.
Abstract: Equine West Nile virus (WNV) encephalomyelitis cases - based on clinical signs and ELISA serology test results - reported to Texas disease control authorities during 2002 were analyzed to provide insights into the epidemiology of the disease within a previously disease-free population. The epidemic occurred between June 27 and December 17 (peaking in early October) and 1,698 cases were reported. Three distinct epidemic phases were identified, occurring mostly in southeast, northwest and then central Texas. Significant (P<0.05) disease clusters were identified in northwest and northern Texas. Most (91.1%) cases had no recent travel history, and most (68.9%) cases had not been vaccinated within the previous 12 months. One-third of cases did not survive, 71.2% of which were euthanatized. The most commonly reported presenting signs included ataxia (69%), abnormal gait (52%), muscle fasciculations (49%), depression (32%) and recumbency (28%). Vaccination status, ataxia, falling down, recumbency and lip droop best explained the risk of not surviving WNV disease. Results suggest that the peak risk period for encephalomyelitis caused by WNV may vary substantially among regions within Texas. Recumbent horses have a poor prognosis for survival. Vaccines, even if not administered sufficiently in advance of WNV infection within a district, may reduce the risk of death by at least 44%.
Descriptors: West Nile virus, horses, infection, clinical signs, Texas, prognosis, vaccines, death, depression, ataxia, recumbancy.
Ward, M. (2005). Epidemic West Nile virus encephalomyelitis: A temperature-dependent, spatial model of disease dynamics. Preventive Veterinary Medicine. 71(3-4): 253-264. ISSN: 0167-5877.
Descriptors: West Nile virus, viral encephalitis, disease outbreaks, ambient temperature, epidemiological studies, epidemiology, spatial distribution, horses, horse diseases, heat sums, risk factors, geographic information systems, biogeography, disease transmission, models, Indiana.
Notes: In the Special Issue: Proceedings of GISVET'04/edited by W. Martin and P. Durr. Proceedings of a conference held June 23-25, 2004, Ontario, Canada.
Warner, R.D., R.C. Kimbrough, J.L. Alexander, J.J. Rush Pierce, T. Ward, and L.P. Martinelli (2006). Human west nile virus neuroinvasive disease in Texas, 2003 epidemic: Regional differences. Annals of Epidemiology 16(10): 749-755. ISSN: 1047-2797.
Abstract: PURPOSE: Arboviral diseases, such as West Nile virus (WNV) epizootics, tend to be geographically unique because of the biomes that support the vector(s) and reservoir host(s). Understanding such details aids in preventive efforts. We studied the 2003 epidemic of human West Nile neuroinvasive disease (WNND) in Texas because it initially appeared that incidence was not uniform across regions of the state. METHODS: The epidemic was described by age, sex, and region of residence. These variables were used to compare age-specific incidence, standardized cumulative incidence, and age-adjusted relative risk (RR). We verified case data and used routine software, with population estimates from the US Census Bureau. RESULTS: Regardless of sex, risk increased with age. Males had the greater risk (RR, 1.69); however, males aged 5 to 17 years had the greatest RR. Of the five regions compared, two posed more (RRs, 7.98 and 2.14) and one posed less (RR, 0.40) risk than the remainder of the state. Proportions of Culex vector species differed significantly between regions. CONCLUSIONS: During 2003, the risk for WNND varied considerably across Texas. This suggests that various risks for WNV infection deserve additional research for preventive interventions to be regionally appropriate and effective.
Descriptors: West Nile virus, epizootics, reservoir hosts, preventive efforts, epidemic, variables, risk, Culex vector, Texas.
Yaremych, S.A., R.E. Warner, P.C. Mankin, J.D. Brawn, A. Raim and R. Novak (2005). West Nile virus and high death rate in American crows. S.K. Majumdar, J.E. Huffman, F.J. Brenner and A.I.E. Panah Wildlife Diseases: Landscape Epidemiology, Spatial Distribution and Utilization of Remote Sensing Technology., Pennsylvania Academy of Science, Easton., p. Chapter pagination: 200-204, i-ix. ISBN: 0945809190.
Descriptors: Corvus brachyrhynchos, dipteran parasites, culicidae, viral diseases, West Nile virus, viral prevalence, epidemiology and associated mortality rate, satellite tracking study, transmission of viruses, mortality, mortality rate, USA.
Zak, I.T., D. Altinok, J.R. Merline, S. Chander, and K.K. Kish (2005). West Nile virus infection. American Journal of Roentgenology 184(3): 957-961. ISSN: 0361-803X.
Abstract: OBJECTIVE: Our objective is to present a brief review of the clinical aspects of West Nile virus infection with emphasis on the spectrum of MRI findings. CONCLUSION: West Nile virus infection has become endemic in the United States and radiologists should become aware of the diverse imaging appearances in the central nervous system.
Descriptors: West Nile fever diagnosis, West Nile virus, magnetic resonance imaging, literature review.
Zhang, J.S., P.H. Zhang, B.Y. Si, H. Yang, and W.C. Cao (2005). [Comparison and discrimination of the biological characteristics between West Nile virus and Japanese encephalitis virus]. Chinese Journal of Experimental and Clinical Virology 19(4): 340-343.
Abstract: BACKGROUND: To compare the biological characteristics of West Nile virus (WNV) and Japanese encephalitis virus (JEV), including cells sensitivity, pathogenicity, viral morphology, as well as the results of immunological and molecular biological detection. METHODS: Cytopathic effect (CPE) and pathogenicity were observed in C6/36 cells and in suckling mice inoculated intracerebrally with the WNV or JEV, respectively. The sliced tissue samples for electron microscopic examination were prepared for the morphologic observation of the viruses. Serum antibody to WNV or JEV was detected using indirect immunofluorescence assay (IFA), and the viral RNA was analyzed by RT-PCR method. RESULTS: WNV or JEV-caused CPE was characterized by cell fusion and cell shedding, respectively. There was no significant difference in the pathogenicity to suckling mice between WNV and JEV. The morphologic observation showed that the shape and size of the two virions were similar. WNV and JEV were found to have antigenic cross-reactivity. The viral RNA could be detected from both WNV and JEV samples with universal primer set, but only nucleoside fragments of corresponding virus could be amplified when specific primers were used. CONCLUSION: CPE in C6/36 cell and detection of the viral RNA should be useful in discrimination of WNV and JEV, and simultaneously examining the titers of serum antibodies against WNV and JEV may be helpful to diagnosis of infection with these agents.
Descriptors: West Nile virus, Japanese encephalitis virus, biological characteristics, pathogenicity, morphology, viral RNA, diagnosis.
Language of Text: Chinese.
Zohrabian, A., E.B. Hayes, and L.R. Petersen (2006). Cost-effectiveness of West Nile virus vaccination. Emerging Infectious Diseases 12(3): 375-380. ISSN: 1080-6040 .
Abstract: West Nile virus (WNV) was first detected in the Western Hemisphere in 1999 in New York City. From 1999 through 2004, >16,600 cases of WNV-related illnesses were reported in the United States, of which >7,000 were neuroinvasive disease and >600 were fatal. Several approaches are under way to develop a human vaccine. Through simulations and sensitivity analysis that incorporated uncertainties regarding future transmission patterns of WNV and costs of health outcomes, we estimated that the range of values for the cost per case of WNV illness prevented by vaccination was US 20,000 dollars-59,000 dollars(mean 36,000 dollars). Cost-effectiveness was most sensitive to changes in the risk for infection, probability of symptomatic illness, and vaccination cost. Analysis indicated that universal vaccination against WNV disease would be unlikely to result in societal monetary savings unless disease incidence increases substantially over what has been seen in the past 6 years.
Descriptors: vaccination economics, viral vaccines, West Nile fever prevention and control, cost benefit analysis, decision trees, health care costs, mortality.