Allison, A., N. Gottdenker, and D. Stallknecht (2005). Wintering of neurotropic velogenic Newcastle disease virus and West Nile virus in double-crested cormorants (Phalacrocorax auritus) from the Florida keys. Avian Diseases. 49(2): 292-297. ISSN: 0005-2086.
Abstract: During November 2002, six double-crested cormorants (DCCs; Phalacrocorax auritus) were found moribund in Big Pine Key, FL, exhibiting clinical signs indicative of neurologic disease. Postmortem diagnostic evaluations were performed on two adult birds. Virulent Newcastle disease virus (NDV) was isolated from a cloacal swab from cormorant 1. West Nile virus (WNV) was isolated from the brain and lung of cormorant 2. Nucleotide sequence analysis of a portion of the fusion (F) protein gene of the NDV cormorant isolate revealed it shared a 100% deduced amino acid identity with only two viruses: the 1992 epizootic cormorant isolate from Minnesota and the 1992 turkey isolate from North Dakota. The epidemiologic significance of the recognition of virulent NDV on cormorant wintering grounds during a nonepizootic period, in addition to the potential implications of the concurrent isolation of NDV and WNV from cormorants, is discussed.
Descriptors: Phalacrocorax, wild birds, bird diseases, alternative hosts, Newcastle disease virus, Newcastle disease, West Nile virus, viral diseases, animals, humans, overwintering, nucleotide sequences, amino acid sequences, pathogen identification, epidemiology, geographical distribution, disease outbreaks, disease reservoirs, Florida.
Language of Text: Summary in Spanish.
Gingrich, J.B., R.D. Anderson, G.M. Williams, L. O'Connor, and K. Harkins (2006). Stormwater ponds, constructed wetlands, and other best management practices as potential breeding sites for West Nile virus vectors in Delaware during 2004. Journal of the American Mosquito Control Association 22(2): 282-291.
Abstract: We performed longitudinal surveys of mosquito larval abundance (mean mosquito larvae per dip) in 87 stormwater ponds and constructed wetland in Delaware from June to September 2004. We analyzed selected water quality factors, water depth, types of vegetation, degree of shade, and level of insect predation in relation to mosquito abundance. The 2004 season was atypical, with most ponds remaining wet for the entire summer. In terms of West Nile virus (WNV) vectors, wetlands predominantly produce Aedes vexans, Culex pipiens pipiens, and Culex restuans. Retention ponds generally produced the same species as wetlands, except that Cx. p. pipiens was more abundant than Cx. restuans in retention ponds. Aedes vexans and Culex salinarius were the most abundant species to Conservation Restoration Enhancement Program ponds. Sand filters uniquely produced high numbers of Cx. restuans, Cx. p. pipiens, and Aedes japonicus japonicus, a newly invasive vector species. Site that alternately dried and flooded, mostly detention ponds, forebays of retention ponds, and some wetlands often produced Ae. vexans, an occasional WNV bridge vector species. Overall, seasonal distribution of vectors was bimodal, with peaks occurring during early and late summer. Ponds with shallow sides and heavy shade generally produced an abundance of mosquitoes, unless insect predators were abundant. Bright, sunny ponds with steep sides and little vegetation generally produced the fewest mosquitoes. The associations among mosquito species and selected vegetation types are discussed.
Descriptors: Culicidae virology, insect vectors, West Nile virus, Aedes, Anopheles, Culex virology, Delaware, fresh water ecology, population density, seasons, waste disposal.
Godsey, M.J., M. Blackmore, N. Panella, K. Burkhalter, K. Gottfried, L. Halsey, R. Rutledge, S. Langevin, R. Gates, and K. Lamonte (2005). West Nile virus epizootiology in the southeastern United States, 2001. Vector Borne and Zoonotic Diseases. 5(1): 82-89. ISSN: 1530-3667.
Descriptors: West Nile virus, virus transmission, insect vectors, Culex, Culiseta melanura, mosquitoes, disease reservoirs, birds, disease detection, antibody detection, seroprevalence, chickens, sentinel animals, Southeastern United States, Florida, Georgia.
Hull, J., A. Hull, W. Reisen, Y. Fang, and H. Ernest (2006). Variation of West Nile virus antibody prevalence in migrating and wintering hawks in central California. Condor 108(2): 435-439. ISSN: 0010-5422.
Abstract: To assess the extent of West Nile virus (WNV) exposure of migrating (Marin Headlands) and wintering (Central Valley) hawks in California, plasma from 271 Red-tailed Hawks (Buteo jamaicensis), 19 Red-shouldered Hawks (B. lineatus), and 30 Cooper's Hawks (Accipiter cooperii) was tested for WNV antibodies during the winter of 2004-2005. WNV antibodies were found in 5% of migrating and 15% of wintering Red-tailed Hawks, 20% of migrating and 58% of wintering Red-shouldered Hawks, and 13% of migrating Cooper's Hawks. No individuals demonstrated visible signs of WNV illness. Red-tailed Hawks that tested positive for WNV antibodies displayed no difference from Red-tailed Hawks without WNV antibodies in weight to wing chord ratio or white blood cell counts. In the Central Valley, WNV antibodies were significantly more prevalent in Red-shouldered Hawks than in Red-tailed Hawks. Significantly more Red-tailed Hawks sampled on wintering grounds tested positive for WNV antibodies than Red-tailed Hawks sampled during migration.
Descriptors: Accipiter cooperii, Buteo jamaicensis, Buteo lineatus, migration, viral diseases, West Nile virus, antibody prevalence, temporal variation, migrating and wintering individuals, immune response, viral disease antibody prevalence, California, central.
Language of Text: English, Spanish.
Joyner, P.H., S. Kelly, A.A. Shreve, S.E. Snead, J.M. Sleeman, and D.A. Pettit (2006). West Nile virus in raptors from Virginia during 2003: clinical, diagnostic, and epidemiologic findings. Journal of Wildlife Diseases 42(2): 335-344. ISSN: 0090-3558.
Abstract: Sixty-one birds of prey admitted to The wildlife Center of Virginia (WCV; Waynesboro, Virginia, USA) from June to November 2003 were tested for West Nile 'Arus (WNV) infection. Choanal and/or cloacal swabs were obtained and submitted to Virginia's Division of Consolidated Laboratory Services (Richmond, Virginia, USA) for analysis with real-time reverse transcriptase polymerase chain reaction (RT-PCR). Forty birds of prey were positive for WNV by RT-PCR. Five avian families and nine species of raptors were represented, with great horned owls (Bubo virginianus) and red-tailed hawks (Buteo jamaicensis) most frequently affected. Presenting clinical signs were consistent with previous reports of WNV infection in raptors; however, these differed between species. Of WNV positive birds, nonspecific signs of illness were the most common clinical findings, particularly in red-tailed hawks; signs included dehydration (n=20), emaciation (n =18), and depression (n =15). Neurologic abnormalities were frequently identified, especially in great horned owls, and included head tremors (n=17), ataxia (n=13), head incoordination (n=7), torticollis (n=3), nystagmus (n=3), and bead tilt (n=3). Great horned owls exhibited aNemia and leukocytosis with heterophilia, eosinophilia, and monocytosis consistent with chronic inflammation. Red-tailed hawks were aNemic with a heterophilic leukocytosis and regenerative left shift. The majority of WNV cases occurred during August and September; there was a marked increase in the number of raptors admitted to WCV during these months followed by a marked decrease during October, November, and December. This pattern differed from mean monthly admissions during the previous 10 years and suggests a negative impact on local raptor populations. The effects of WNV on avian populations are largely unknown; however, because of their ecological importance, further investigation of the effects of WNV on raptor populations is warranted.
Descriptors: falconiformes, strigiformes, viral diseases, West Nile virus, clinical, diagnostic and epidemiologic findings, transmission of viruses, Virginia.
Owen, J., F. Moore, N. Panella, E. Edwards, R. Bru, M. Hughes, and N. Komar (2006). Migrating birds as dispersal vehicles for West Nile virus. EcoHealth 3(2): 79-85. ISSN: 1612-92021612-9210.
Descriptors: West Nile virus, migrating birds, dispersal vehicles, locomotor activity, virus spread.
Reisen, W.K., Y. Fang, H.D. Lothrop, V.M. Martinez, J. Wilson, P. O'Connor, R. Carney, B. Cahoon Young, M. Shafii, and A.C. Brault (2006). Overwintering of West Nile virus in southern California. Journal of Medical Entomology 43(2): 344-355. ISSN: 0022-2585.
Abstract: West Nile virus (family Flaviviridae, genus Flavivirus, WNV) invaded southern California dining 2003, successfully overwintered, amplified to epidemic levels, and then dispersed to every county in the state. Although surveillance programs successfully tracked and measured these events, mechanisms that allowed the efficient overwintering and subsequent amplification of WNV have not been elucidated. Our current research provided evidence for three mechanisms whereby WNV may have persisted in southern California during the winters of 2003-2004 and 2004-2005: 1) continued enzootic transmission, 2) vertical transmission by Culex mosquitoes, and 3) chronic infection in birds. WNV was detected in 140 dead birds comprising 32 species, including 60 dead American crows, thereby verifying transmission during the November-March winter period. Dead American crows provide evidence of recent transmission because this species always succumbs rapidly after infection. However, WNV RNA was not detected concurrently in 43,043 reproductively active female mosquitoes comprising 11 species and tested in 1,258 pools or antibody in sera from 190 sentinel chickens maintained in 19 flocks. Although efficient vertical transmission by WNV was demonstrated experimentally for Culex tarsalis Coquillett infected per os, 369 females collected diapausing in Kern County and tested in 32 pools were negative for WNV. Vertical transmission was detected in Culex pipiens quinquefinciatus Say adults reared from field-collected immatures collected from Kern County and Los Angeles during the summer transmission period. Chronic infection was detected by finding WNV RNA in 34 of 82 birds that were inoculated with WNV experimentally, held for >6 wk after infection, and then necropsied. Frequent detection of WNV RNA in kidney tissue in experimentally infected birds >6 wk postinfection may explain, in part, the repeated detection of WNV RNA in dead birds recovered during winter, especially in species such as mourning doves that typically do not die after experimental infection. In summary, our study provides limited evidence to support multiple modes of WNV persistence in southern California. Continued transmission and vertical transmission by Culex p. quinquefasciatus Say seem likely candidates for further study.
Descriptors: aves, viral diseases, West Nile virus, overwintering, transmission of viruses, California, south, viral disease overwintering.
Sabio, I.J., A.J. Mackay, A. Roy, and L.D. Foil (2006). Detection of West Nile virus RNA in pools of three species of ceratopogonids (Diptera: Ceratopogonidae) collected in Louisiana. Journal of Medical Entomology 43(5): 1020-1022. ISSN: 0022-2585.
Abstract: Light traps were used to collect ceratopogonids in East Baton Rouge parish, Louisiana. In total, 46,496 ceratopogonids were sorted from 4,968 light trap collections from 20 November 2002 through 25 November 2004. Two hundred and nine pools containing specimens of 18 species of Culicoides Latreille, seven pools containing specimens of Atrichopogon Kieffer, and five pools containing specimens of Forcipomyia Meigen were tested for West Nile virus (family Flaviviridae, genus Flavivirus, WNV) RNA using real-time reverse transcriptase polymerase chain reaction. Five out of the 209 pools of Culicoides specimens were positive for WNV RNA.
Descriptors: West Nile virus, detection, trap collection, Culicoides, RNA, reverse transcriptase polymerase chain reaction, Louisiana.