115 citations from the Agricola Database
January 1996 - March 1999
Water Quality Information Center
This electronic bibliography is a continuation of Cryptosporidium: Water Quality, Agriculture and Health Effects I (1992-1995). It is intended primarily to provide awareness of investigations and discussions of a topic and is not intended to be in-depth and exhaustive. The inclusion or omission of a particular publication or citation should not be construed as endorsement or disapproval. Citations are arranged alphabetically by title and abstracts are included where available. All citations are in English unless otherwise noted.
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Descriptors: Cryptosporidium-parvum, Environmental-aspects, Congresses, Drinking-water-Contamination.
Descriptors: beef-cattle, cryptosporidium-parvum, feces, water-pollution, rangelands, life-cycle, wildlife, waterborne-diseases, zoonoses, surface-water, oocytes, protozoal-infections, cryptosporidiosis.
Abstract: The ability to determine inactivation rates of Cryptosporidium parvum oocysts in environmental samples is critical for assessing the public health hazard of this gastrointestinal parasite in watersheds. We compared a dye permeability assay, which tests the differential uptake of the fluorochromes 4'-6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI) by the oocysts, with an in vitro excystation assay, which tests their ability to excyst and, thus, their metabolic potential and potential for infectivity. Formaldehyde-fixed (killed) oocysts and untreated oocysts were permeabilized with sodium hypochlorite and subjected to both assays. The results of the dye permeability assays were the same, while the excystation assay showed that no excystation occurred in formaldehyde-fixed oocysts. This confirmed that oocyst wall permeability, rather than metabolic activity potential, was the basis of the dye permeability viability assessment. A previously developed protocol for determining viability or oocysts in soil and sediment was used to examine further the use or oocyst permeability status as an indicator of oocyst viability in fecal material stored at 4 degrees C and in water at various temperatures. The dye permeability assay further showed that an increase in the intermediate population of oocysts permeable to DAPI but not to PI occurred over time. There was also a steady population of oocysts permeable to both dyes. Further experiments with purified oocysts suspended in distilled water showed that the shift in oocyst populations from impermeable to partially permeable to fully permeable was accelerated at temperatures above 4 degrees C. This sequence of oocyst permeability changes was taken as an indicator of the oocyst inactivation pathway. Using the dye permeability results, inactivation rates of oocysts in two fecal pools stored in the dark at 4 degrees C for 410 and 259 days were estimated to be 0.0040 and 0.0056 oocyst day-1, respectively. The excystation assay gave similar inactivation rates of 0.0046 and 0.0079 oocyst day-1. These results demonstrate the utility of the dye permeability assay as an indicator of potential viability and infectivity of oocysts, especially when combined with improved microscopic methods for detection of oocysts in soil, turbid water, and sediments.
Descriptors: drinking-water, surface-water, water-supply, cryptosporidium-parvum, giardia-duodenalis, infection, risk-assessment, public-health.
Descriptors: cryptosporidium-parvum, tubulin, structural-genes, cloning, nucleotide-sequences, amino-acid-sequences, molecular-sequence-data, genbank, y12615.
Descriptors: elaphe, cryptosporidium, protozoal-infections, bile-ducts, stomach-mucosa, histopathology, case-reports.
Descriptors: calves, cryptosporidium-parvum, treatment, disease-prevention.
Descriptors: calves, cryptosporidiosis, experimental-infections, cryptosporidium-parvum,
cd4+-lymphocytes, cd8+-lymphocytes, cell-mediated-immunity, ileum, intestinal-mucosa,
peyer-patches, t-lymphocytes, villi, literature-reviews.
Abstract: To better understand the immune mechanisms important for clearing of the primary infection and the subsequent development of resistance to Cryptosporidium parvum infection, several groups have recently characterised changes within the lymphoid cell population of the intestinal mucosa and associated lymphoid tissue in calves with cryptosporidiosis. In naive animals, infection results in a significant increase in the number of CD4+ and CD8+ T cells present within the intraepithelial lymphocyte population, lamina propria and Peyer's patch of the ileum. This is accompanied by a rapid and transient increase in the number of gamma/delta T cells present within the intestinal villi. In response to a challenge infection in immune calves, there is a substantial increase in the number of CD4+ T cells present in the Peyer's patch of the ileum and a specific localisation of CD8+ T cells to the epithelium of the intestinal villi. Together, these data demonstrate that C. parvum elicits a strong cell-mediated response following both primary and secondary infections in calves, and that CD8+ T cells may play an important role in the bovine immune response to C. parvum infection.
Descriptors: cryptosporidium, drinking-water, water-quality, concentration, centrifugation, analytical-methods, water-microbiology, continuous-centrifugation.
Descriptors: cryptosporidium-parvum, codons, taxonomic-status, toxoplasma-gondii, plasmodium-falciparum, eimeria-tenella, plasmodium-berghei, entamoeba-histolytica, babesia-bovis.
Descriptors: cryptosporidium-parvum, eimeria-tenella, toxoplasma-gondii, phosphofructokinase, pyruvate-kinase, enzyme-activity, anaerobiosis, species-differences.
Descriptors: agricultural-research, USDA, research-projects, cryptosporidium, protozoal-infections, leptospirosis, leptospira, strains, diagnostic-techniques, borrelia-burgdorferi, ixodes-scapularis, disease-vectors, diptera, pest-control, human-diseases, disease-control.
Descriptors: foals, cryptosporidium, diarrhea, life-cycle, feces, screening, diagnosis, antiinfective-agents, antiinflammatory-agents, cryptosporidiosis, antiprotozoal-agents.
Descriptors: cryptosporidium, cryptosporidiosis, pathogenesis, symptoms, diagnosis, medical-treatment, zoonoses, disease-control.
Descriptors: cats, cryptosporidiosis, cryptosporidium-parvum, duodenum, inflammation, intestinal-diseases, symptoms, diagnosis, clindamycin, tylosin, drug-therapy, case-reports, duodenitis.
Descriptors: freshwater-catfishes, aquarium-fishes, cryptosporidiosis, cryptosporidium, intestines, case-reports.
Descriptors: cryptosporidium, infections, organs, mice, zoonoses, laboratory-hazards, cryptosporidiosis.
Descriptors: Cryptosporidium, Cryptosporidiosis, Water-quality.
Abstract: Discusses cryptosporidium and the disease it causes, as well as steps to take to prevent the disease from occurring.
Descriptors: Cryptosporidiosis, Cryptosporidium.
Descriptors: dugong-dugon, cryptosporidium, cryptosporidiosis, small-intestine, histopathology, symptoms, case-reports, Queensland.
Descriptors: calves, cryptosporidium-parvum, experimental-infections, cryptosporidiosis, excretion, cattle-dung, diarrhea, oral-administration, newborn-animals, cd4+-lymphocytes, cd8+-lymphocytes, cell-mediated-immunity, ileum, gene-expression, messenger-rna, interferon, interleukins, intestinal-mucosa, lymph-nodes, t-lymphocytes, interleukin-12.
Abstract: Cryptosporidium parvum oocysts infectious to neonatal BALB/c mice were processed by the cellulose-acetate membrane (CAM) filter dissolution method to determine if the procedure that utilizes acetone incubation and alcohol centrifugations alters their viability (determined by in vitro excystation) or infectivity (determined by infectivity bioassay). In addition, most oocysts with altered viability by desiccation, heat inactivation, and snap freezing that were processed by the CAM filter dissolution method were nonrefractile, unstained oocyst ghosts. The remaining organisms, oocyst shells, were lightly stained with the acid-fast stain. Infectious oocysts retained their infectivity and nonviable oocysts (oocyst shells) retained their morphology when processed by the CAM dissolution method. Infectious oocysts, oocyst shells, and oocyst ghosts produced positive reactions of similar intensity in direct immunofluorescence antibody staining, utilizing the MERIFLUOR Cryptosporidium/Giardia test kit. Cryptosporidium oocysts recovered from finished drinking water by the CAM dissolution method can be subjected to testing for their viability and infectivity.
Descriptors: water-microbiology, water-quality, drinking-water, food-contamination, cryptosporidium.
Descriptors: dairy-cattle, cryptosporidium, oocysts, feces, detection, case-reports, scotland.
Descriptors: rain, drinking-water, water-supply, contamination, cryptosporidium, oocysts, giardia, cysts, detection, antibodies, public-health, risk-assessment, united-states-virgin-islands, potable-water-supply.
Descriptors: drinking-water, USA, New York.
Descriptors: cryptosporidium-parvum, cryptosporidiosis, lymphocyte-transformation, cytokines, t-lymphocytes, phenotypes, spleen-cells, age-differences, interferon, interleukin-5, immune-response, disease-resistance, young-animals, mice.
Descriptors: dna, genetic-polymorphism, polymerase-chain-reaction, diagnostic-techniques, detection, protozoal-infections, random-amplified-polymorphic-dna, dna-primers.
Descriptors: cryptosporidium-parvum, ribosomal-dna, dna-sequencing, polymerase-chain-reaction, differentiation, nucleotide-sequences, genetic-variation, strain-differences, molecular-sequence-data.
Descriptors: animals, cryptosporidiosis, disease-control, cryptosporidium-parvum, surface-proteins, recombinant-proteins, vaccines, genetic-code, gene-transfer, dna, nucleotide-sequences, patents, USDA, USA, us005591434a.
Descriptors: cryptosporidium-parvum, disulfiram, metabolites, immunomodulators, immunosuppression, rats, cryptosporidiosis, chemoprophylaxis, small-intestine, biliary-system, large-intestine.
Descriptors: chickens, cryptosporidium-baileyi, cryptosporidiosis, pathogenesis, t-2-toxin, zearalenone, oral-administration, dosage, oocysts, immunity, humoral-immunity, liveweight-gain, thymus-gland, bursa-fabricii, weight.
Descriptors: cryptosporidium-parvum, oocysts, pasteurization, water, milk, infectivity, mice,
bioassays, disease-control, foodborne-diseases, waterborne-diseases, sterilizing,
Abstract: Cryptosporidium parvum is a major cause of diarrheal disease in humans and has been identified in 78 other species of mammals. The oocyst stage, excreted in feces of infected humans and animals, has been responsible for recent waterborne outbreaks of human cryptosporidiosis. High temperature and long exposure time have been shown to render oocysts (suspended in wafer) noninfectious, but for practical purposes, it is important to know if high-temperature-short-time conditions (71.7 degrees C for 15 s) used in commercial pasteurization are sufficient to destroy infectivity of oocysts. In this study, oocysts were suspended in either water or whole milk and heated to 71.7 degrees C for 15, 10, or 5 s in a laboratory-scale pasteurizer. Pasteurized and nonpasteurized (control) oocysts were then tested for the ability to infect infant mice. No mice (0 of 177) given 10(5) oocysts pasteurized for 15, 10, or 5 s in either water or milk were found to be infected with C. parvum on the basis of histologic examination of the terminal ileum. In contrast, all (80 of 80) control mice given nonpasteurized oocysts were heavily infected. These data indicate that high-temperature-short-time pasteurization is sufficient to destroy the infectivity of C. parvum oocysts in water and milk.
Descriptors: calves, newborn-animals, cryptosporidiosis, cryptosporidium-parvum, veterinary-products, chemoprophylaxis, oocysts, experimental-infections, diarrhea, feces, liveweight-gain, disease-course, duration.
Descriptors: cryptosporidium-parvum, oocytes, viability, freezing, thawing, cold-storage,
infectivity, bioassays, mice.
Abstract: Microcentrifuge tubes containing 8 X 10(6) purified oocysts of Cryptosporidium parvum suspended in 400 microliters of deionized water were stored at 5 degrees C for 168 h or frozen at -10, -15, -20, and -70 degrees C for 1 h to 168 h and then thawed at room temperature (21 degrees C). Fifty microliters containing 10(6) oocysts was administered to each of five to seven neonatal BALB/c mice by gastric intubation. Segments of ileum, cecum, and colon were taken for histology from each mouse 72 or 96 h later. Freeze-thawed oocysts were considered viable and infectious only when developmental-stage C. parvum organisms were found microscopically in the tissue sections. Developmental-stage parasites were not found in tissues from any mice that received oocysts frozen at -70 degrees C for 1, 8, or 24 h. All mice that received oocysts frozen at -20 degrees C for 1, 3, and 5 h had developmental-stage C. parvum; one of 6 mice that received oocysts frozen at -20 degrees C for 8 h had a few developmental-stage parasites; mice that received oocysts frozen at -20 degrees C for 24 and 168 h had no parasites. All mice that received oocysts frozen at -15 degrees C for 8 and 24 h had developmental-stage parasites; mice that received oocysts frozen at -15 degrees for 168 h had no parasites. All mice that received oocysts frozen at -10 degrees C for 8, 24, and 168 h and those that received oocysts stored at 5 degrees C for 168 h had developmental stage parasites. These findings demonstrate for the first time that oocysts of C parvum in water can retain viability and infectivity after freezing and that oocysts survive longer at higher freezing temperatures.
Descriptors: calves, lactose, xylose, blood-sugar, galactose, blood, insulin, diarrhea, cryptosporidium, coronavirus, small-intestine, intestinal-absorption, metabolites, hormones.
Descriptors: horses, feral-herds, wild-animals, public-domain, cryptosporidium-parvum, giardia-duodenalis, feces, strongylidae, watersheds, california, nevada.
Descriptors: drinking-water, contaminants, waterborne-diseases.
Descriptors: cats, cryptosporidium-parvum, igg, blood-serum, elisa, antibody-testing, seroprevalence, Colorado.
Descriptors: cryptosporidium-parvum, karyotypes, chromosomes, pulsed-field-electrophoresis, southern-blotting, restriction-endonucleases, enzyme-activity, molecular-mapping, dna-probes, dna-hybridization.
Descriptors: drinking-water, disinfection, pathogens, cryptosporidium, public-health.
Descriptors: dairy-cows, calves, cryptosporidium-parvum, infection, cryptosporidiosis, oocysts,
feces, cow-housing, calf-housing, walls, floors, surfaces, prepartum-period, postpartum-period,
Abstract: To describe patterns of testing for Cryptosporidium oocysts in stool samples, Connecticut laboratories were surveyed. Different detection methods were used. Most laboratories examined stools specifically for Cryptosporidium only on physician request. The rate of positive tests varied widely (0 to 28%). Higher rates of positivity were associated with the use of monoclonal antibody methods, the use of two or more staining procedures, and testing of stool specimens in addition to those requested by physicians.
Descriptors: calves, dairy-herds, cryptosporidium-parvum, cryptosporidiosis, chemoprophylaxis,
oral-vaccination, probiotics, lactic-acid-bacteria, diarrhea, oocysts, feces, disease-prevention,
Descriptors: cryptosporidium-parvum, oocysts, disinfection, ammonia, ethylene-oxide,
methyl-bromide, carbon-monoxide, formaldehyde.
Abstract: Purified oocysts of Cryptosporidium parvum suspended in approximately 400 microliters of phosphate-buffered saline or deionized water in microcentrifuge tubes were exposed at 21 to 23 degrees C for 24 h to a saturated atmosphere of ammonia, carbon monoxide, ethylene oxide, formaldehyde, or methyl bromide gas. Controls were exposed to air. Oocyts in each tube were then rinsed and resuspended in fresh, deionized water, and 1 million oocysts exposed to each gas were orally administered to each of three to six neonatal BALB/c mice in replicate groups. Histologic sections of ileum, cecum, and colon tissues taken from each mouse 72 h after oral administration of oocysts were examined microscopically to determine if infection had been established. All 15 mice given oocysts exposed to carbon monoxide had numerous developmental stages of cryptosporidium in all three intestinal segments. Of 10 mice given oocysts exposed to formaldehyde, 6 had a few developmental stages of cryptosporidium in the ileum. No mice given oocysts exposed to ammonia, ethylene oxide, or methyl bromide were found to be infected. These findings indicate the efficacy of these low-molecular-weight gases (ammonia, ethylene oxide, and methyl bromide) as potential disinfectants for C. parvum oocysts where soil, rooms, buildings, tools, or instruments might be contaminated.
Descriptors: host-parasite-relationships, genetic-variation, echinococcus, giardia,
cryptosporidium, species, characterization, virulence, epidemiology, evolution.
Abstract: Fecal droppings of migratory Canada geese, Branta canadensis, collected from nine sites near the Chesapeake Bay (Maryland), were examined for the presence of Cryptosporidium parvum and Giardia spp. Cryptosporidium sp. oocysts were found in feces at seven of nine sites, and Giardia cysts were found at all nine sites. The oocysts from three sites were infectious for mice and molecularly identified as the zoonotic genotype of Cryptosporidium parvum. Waterfowl can disseminate infectious C. parvum oocysts in the environment.
Abstract: Oocysts of Cryptosporidium parvum were obtained from an experimentally infected newborn goat. After purification, the oocysts were homogenised and the activities of the glycolytic enzymes measured in the different subcellular fractions. All of the activities of the Embden-Meyerhoff pathway were located in the non-sedimentable, cytoplasmic fraction. Under the conditions used, hexokinase activity was below the limits of detection. The pathway is also characterised by the presence of a pyrophosphate-dependent phosphofructokinase and a carbon dioxide-fixing cycle comprising phosphoenolpyruvate carboxylase, malate dehydrogenase and malate dehydrogenase (decarboxylating) activities. The data presented in this paper suggest that the infective stage of this parasite probably relies on substrate-level phosphorylation for energy generation.
Abstract: Immunological control of infection with cryptosporidia in mice is dependent on CD4+ T cells and the production of gamma interferon (IFN-gamma), but to date, the mucosal T cells which produce IFN-gamma local to the infection have not been characterized. We previously showed that immunity against the gastric parasite Cryptosporidium muris could be adoptively transferred to adult SCID (severe combined immunodeficiency) mice with small intestinal intraepithelial lymphocytes (IEL) from previously infected immunocompetent mice, but only if the donor CD4+ T cells were intact. The present investigation examined whether IFN-gamma was important in the effector mechanisms mediated by immune IEL in SCID mice. The development of resistance against C. muris infection in SCID mice given immune IEL was prevented by treatment with a hamster anti-mouse IFN-gamma-neutralizing monoclonal antibody, but following cessation of antibody treatment, the mice recovered from infection. In further experiments, an enzyme-linked immunospot (ELISPOT) technique was used to compare frequencies of IFN-gamma-producing cells in activated T-cell populations from C. muris-immune and naive donor mice. Stimulation with concanavalin A or a rat anti-mouse CD3 monoclonal antibody resulted in detection of greater numbers of cells producing IFN-gamma from immune than naive EL populations. Small numbers of IEL from C. muris-immune mice, but not from naive mice, also produced IEN-gamma when cultured with soluble oocyst antigen, but this occurred only if gamma-irradiated spleen cells were cocultured with the immune IEL. These results suggested that IEL were important in the generation of immunity to Cryptosporidium and that one of their crucial functions. was to produce IFN-gamma at the site of infection.
Descriptors: messenger-rna, polymerase-chain-reaction, nucleotide-sequences, amino-acid-sequences, gene-expression, molecular-sequence-data, genbank, af076438.
Descriptors: cryptosporidium, cryptosporidium-parvum, ribosomal-dna, ribosomal-rna, genes,
genetic-polymorphism, genetic-markers, dna-fingerprinting, polymerase-chain-reaction,
nucleotide-sequences, strains, identification, human-isolates, clinical-isolates, animal-isolates,
molecular-sequence-data, genbank, l16996.
Abstract: Oocysts of the protozoan parasite Cryptosporidium parvum are found in most surface waters and can contaminate municipal water supplies, as demonstrated by recent outbreaks of cryptosporidiosis. A method capable of fingerprinting C. parvum isolates from the environment would facilitate the study of epidemiology and transmission cycles and aid in the implementation of preventive measures to reduce water contamination by oocysts. In this study, we report polymorphism in C. parvum isolates on the basis of analysis of random amplified polymorphic DNA and nucleotide sequences in a region of the 18S rRNA and the internal transcribed spacer 1. Isolate-specific primers for these two regions were designed, and PCR tests capable of discriminating between isolates were developed. In both PCR assays, the five C. parvum isolates analyzed segregated into two subgroups. One group consisted of isolates that originated directly from human patients, and the other group had various host origins and had been propagated in laboratory animals. These results demonstrate the feasibility of distinguishing C. parvum isolates by sequence-specific PCR tests.
Abstract: A method to detect viable Cryptosporidium parvum oocysts was developed. Polyclonal immunoglobulin G against C. parvum oocyst and sporozoite surface antigens was purified from rabbit immune serum, biotinylated, and bound to streptoavidin-coated magnetic particles. C. parvum oocysts were captured by a specific antigen-antibody reaction and magnetic separation. The oocysts were then induced to excyst, and DNA was extracted by heating at 95 degrees C for 10 min. A 452-bp fragment of C. parvum DNA was amplified by using a pair of C. parvum-specific primers in PCR. The method detected as few as 10 oocysts in purified preparations and from 30 to 100 oocysts inoculated in fecal samples. The immunomagnetic capture PCR (IC-PCR) product was identified and characterized by a nested PCR that amplified a 210-hp fragment, followed by restriction endonuclease digestion of the IC-PCR and nested-PCR products at the styI site and a nonradioactive hybridization using an internal oligonucleotide probe labeled with biotin. PCR specificity was also tested, by using DNAs from other organisms as templates. In the control experiments, inactivated oocysts were undetectable, indicating the ability of this method to differentiate between viable and nonviable oocysts. Thus, this system can be used to specifically detect viable C. parvum oocysts in environmental samples with great sensitivity, providing an efficient way to monitor the environment for C. parvum contamination.
Descriptors: zoonoses, livestock, brucellosis, leptospirosis, q-fever, rabies, salmonellosis, campylobacteriosis, cryptosporidiosis, anthrax, dermatomycoses, contagious-ecthyma-virus, disease-transmission, disease-prevention.
Descriptors: cattle, cryptosporidium-parvum, horses, leptospira-interrogans.
Descriptors: trifluralin, profluralin, nitralin, pendimethalin, fluchloralin, antiprotozoal-agents,
cryptosporidium-parvum, pharmaceutical-products, cytotoxicity, growth-inhibitors, efficacy,
Abstract: Despite the evaluation of over 100 antimicrobial drugs, the diarrheal disease cryptosporidiosis has remained refractory to treatment. We report the evaluation of five dinitroaniline herbicides including trifluralin, profluralin, nitralin, pendimethalin, and fluchloralin for anticryptosporidial activity in an in vitro cultivation model of Cryptosporidium parvum. All five compounds exhibited significant anticryptosporidial activities with no corresponding evidence of toxicity. The most active compound was pendimethalin with an IC50 of 0.19 micromolar while nitralin was the least active with an IC50 of 4.5 micromolar. These compounds should be evaluated further in an animal model of cryptosporidiosis.
Descriptors: crassostrea-virginica, cryptosporidium-parvum, oocysts, hemocytes, interactions, in-vitro, phagocytosis.
Descriptors: indicator-species, water-pollution.
Abstract: Corbicula fluminea hemocytes phagocytosed infectious oocysts of Cryptosporidium parvum in vitro. After 15, 30, 60, 90, and 120 min of incubation, averages of 35.8, 58.0, 69.7, 77.7, and 81.6% of the oocysts were phagocytosed by 24.3, 70.0, 78.5, 87.3, and 93.0% of the hemocytes, respectively. A single clam can retain by phagocytosis an average of 1.84 X 10(6) oocysts per ml of hemolymph. C. fluminea bivalves can serve as biological indicators of contamination of wastewaters and agricultural drainages with Cryptosporidium.
Descriptors: goats, kids, cryptosporidiosis, incidence, kid-feeding, symptoms, suckling, milk-substitutes, artificial-rearing, feces, oocysts, morbidity, mortality, hygiene, isolation, aseptic-state, disease-prevention, Spain.
Descriptors: pigeons, cryptosporidium, cryptosporidiosis, outbreaks, diarrhea, weight-losses,
symptoms, histopathology, case-reports, Canary islands.
Abstract: An intestinal disease in pigeons (Columba livia) from the Canary Islands characterized by diarrhea and body weight loss is described. Intestinal cryptosporidiosis was identified in three young pigeons. Cryptosporidia were associated with hyperplasia of the intestinal crypts and moderate inflammatory infiltration in lamina propria. This is the first report of cryptosporidiosis in pigeons.
Abstract: The nature of the host's T-lymphocyte population within the intestinal villi following Cryptosporidium parvum infection was characterized with a bovine model of cryptosporidiosis. In naive animals, infection with C. parvum resulted in substantial increases in the numbers of alpha/beta T cells, both CD4+ (150%) and CD8+ (60%), and of gamma/delta T cells (70%) present within the intestinal villi of the infected ileum. In immune animals, the host T-lymphocyte response to a challenge infection with C. parvum was restricted to alpha/beta T cells. The precise correlation between the accumulation of CD8+ T cells and the normal site of parasite development suggests an important role for CD8+ T cells in the immune animal.
Descriptors: cattle, sheep, goats, cryptosporidium, giardia, protozoal-infections, symptoms, diagnostic-techniques, treatment, disease-control, life-cycle, physiopathology, zoonoses.
Descriptors: dairy-cows, zoonoses, cattle-manure, listeria-monocytogenes, escherichia-coli,
salmonella, mycobacterium-paratuberculosis, viruses, viral-diseases, giardia,
Abstract: Most environmental concerns about waste management either have focused on the effects of nutrients, especially N and P, on water quality or have emphasized odor problems and air quality. Microbes from manure are often low on the priority list for control and remediation, despite the fact that several outbreaks of gastroenteritis have been traced to livestock operations. The pathogens discussed in this paper include protozoans ( Cryptosporidium parvum, Giardia spp. ), bacteria (Listeria monocytogenes, Escherichia coli O157:H7, Salmonella spp. , and Mycobacterium paratuberculosis), and some enteric viruses. Clinical symptoms, prospects for zoonotic infection, and control methods other than the use of antimicrobials are considered. Recommendations to avoid disease transmission include taking steps to ensure the provision of clean, unstressful environments to reduce disease susceptibility and the careful handling and spreading of manure from animals at high risk for infection, especially young calves. Composting and drying of manure decrease the number of viable pathogens. Environmental controls, such as filter strips, also reduce the risk of water contamination.
Abstract: We determined and compared the method detection limits (MDL alpha) of a PCR and an immunofluorescence assay (IFA) for detection of Cryptosporidium parvum oocysts in soils. Based on the MDL alpha and the quantitative nature and stability of the IFA, PCR analysis is not a useful screening step for soil studies of oocyst transport.
Descriptors: hens, chickens, vaccination, eimeria-maxima, glycoproteins, protective-antigens,
gametocytes, maternal-immunity, chicks, antibodies, maternal-transmission, literature-reviews,
oocysts, secretion, feces, passive-immunization, cryptosporidium, plasmodium,
Abstract: Direct microscopy is widely used for the diagnosis of parasitic infections although it often requires an experienced microscopist for accurate diagnosis, is labour intensive and not very sensitive. In order to overcome some of these shortcomings, molecular or nucleic acid-based diagnostic methods for parasitic infections have been developed over the past 12 years. The parasites which have been studied with these techniques include the human Plasmodia, Leishmania, the trypanosomes, Toxoplasma gondii, Entamoeba histolytica, Giardia, Trichomonas vaginalis, Cryptosporidium parvum, Taenia, Echinococcus, Brugia malayi, Wuchereria bancrofti, Loa loa and Onchocerca volvulus. Early methods, which involved hybridisation of specific probes (radiolabelled and non-radiolabelled) to target deoxyribonucleic acid (DNA), have been replaced by more sensitive polymerase chain reaction (PCR)-based aaaays. Other methods, such as PCR-hybridisation assays, PCR-restriction fragment length polymorphism (PCR-RFLP) assays and random amplified polymorphic DNA (RAPD) analysis have also proved valuable for epidemiological studies of parasites. The general principles and development of DNA-based methods for diagnosis and epidemiological studies will be described, with particular reference to malaria. These methods will probably not replace current methods for routine diagnosis of parasitic infections in developing countries where parasitic diseases are endemic, due to high costs. However, they will be extremely useful for genotyping parasite strains and vectors, and for accurate parasite detection in both humans and vectors during epidemiological studies.
Descriptors: cryptosporidium-parvum, oocysts, movement-in-soil, leaching, silt-loam-soils,
clay-loam-soils, sandy-soils, animal-wastes, application-to-land, water-pollution, drinking-water,
microbial-contamination, health-hazards, loamy-sand-soils.
Abstract: The potential for transfer of the protozoan pathogen Cryptosporidium parvum through soil to land drains and, subsequently, water courses following the application of livestock waste to land was monitored in the laboratory using simulated rainfall and intact soil cores. Following irrigation over a 21-day period, Cryptosporidium parvum oocysts applied to the surface of soil cores (initial inoculum concentration 1 X 10(8) oocysts core-1) were detected, albeit in low numbers, in the leachates from clay loam and silty loam soils but not in that from a loamy sand soil. Variations in leaching patterns were recorded between replicate cores. At the end of the study soil cores were destructively sampled to establish the location of oocysts remaining within the soil. Distribution within cores was similar in all three soil types. The majority (72.8 +/- 5.29%) of oocysts were found in the top 2 cm of soil, with numbers decreasing with increasing depth.
Descriptors: broilers, cryptosporidium, disease-prevalence, intestines, bursa-fabricii, trachea, age-differences, histopathology, Morocco.
Abstract: Length and restriction site polymorphism within a 2.8-kb threonine-rich open reading frame from Cryptosporidium parvum was identified and used to determine the genotypes of isolates from calves and humans. In agreement with observations of other genetic loci, all calf isolates were identical at this locus. In contrast, human isolates showed two profiles, one found exclusively in humans and one a superposition of both profiles, which were indicative of heterogeneous parasite populations. PCR fingerprints were consistent with a change in the genetic profile of C. parvum isolates following transmission from bovine to human hosts.
Descriptors: calves, foals, llamas, cryptosporidiosis, case-reports, nosocomial-infections, veterinarians, cryptosporidium-parvum, diarrhea, horizontal-transmission, wisconsin, crias.
Abstract: We examined the efficacy of oral administration of putrescine (a byproduct of arginine metabolism) in the prevention of Cryptosporidium parvum infection of neonatal C57BL-6 mice. Mice were challenged with the parasite at 7 days of age. Mice receiving putrescine from 3 through 10 days of age had a delayed pattern of infection as compared with control mice. Mice receiving putrescine from 3 through 21 days of age did not become infected, whereas control mice were heavily infected. We also tested the hypothesis that putrescine inhibited C. parvum infection by enhancing nitric oxide (NO) production. Mice receiving the NO inhibitor N omega-L-arginine methyl ester (L-NAME) parenterally and putrescine orally did not become infected. Thus, it appears that putrescine inhibits C. parvum infection in an NO-independent manner.
Descriptors: yersinia, cyclospora, cryptosporidium, brucella, mycobacterium.
Descriptors: kids, cryptosporidium, cryptosporidiosis, outbreaks, reconstituted-milk, symptoms, diarrhea, mortality, Brazil.
Descriptors: ostriches, cryptosporidiosis, cryptosporidium, pancreas, symptoms, histopathology,
Abstract: Four 4-month-old ostriches exhibiting poor growth were submitted for necropsy. Gross findings included marked emaciation and pancreatic atrophy. Histological examination revealed pancreatic cryptosporidiosis with large numbers of Cryptosporidium sp. present in the ductal epithelium causing necrosis and lymphoplasmacytic inflammation. The gross and histological findings in these birds and the transmission electron microscopic features of the parasites are described.
Abstract: Cryptosporidium parvum is an enteric protozoan parasite of medical and veterinary importance. Dissemination of environmentally resistant oocysts in surface water plays an important role in the epidemiology of cryptosporidiosis. Although the polymerase chain reaction (PCR) is a well-established technique and is widely used for detecting microorganisms, it is not routinely applied for monitoring waterborne C. parvum. In order to facilitate the application of PCR to the detection of waterborne C. parvum oocysts, a comparison of published PCR protocols was undertaken and different sample-preparation methods tested. The sensitivity of a one-step PCR method, consisting of 40 temperature cycles, was 10 purified oocysts or fewer than 100 oocysts spiked in raw lake water. The detection limit of two primer pairs, one targeting the ribosomal small subunit and another specific for a C. parvum sequence of unknown function, was approximately ten-fold lower than achieved with a primer pair targeting an oocyst shell protein gene. Three cycles of freezing/thawing were sufficient to expose oocyst DNA and resulted in higher sensitivity than proteinase K digestion, sonication or electroporation. Inhibition of PCR by surface water from different local sources was entirely associated with the soluble fraction of lake water. Membrane filtration was evaluated in bench-scale experiments as a means of removing lake water inhibitors and improving the detection limit of PCR. Using gel and membrane filtration, the molecular size of inhibitory solutes from lake water was estimated to less than 27 kDa.
Descriptors: dogs, cryptosporidium-parvum, cryptosporidiosis, oocysts, excretion, feces,
experimental-infections, detection, staining, tests.
Abstract: Six 6-week-old Beagle dogs were fed Cryptosporidium parvum oocysts of calf origin. All 6 dogs shed oocysts in faeces. Greater numbers of oocysts were detected with a Weber concentration technique (formalin-ethyl acetate extraction and NaCl centrifugal flotation) stained with either fluorescent antibody or modified Ziehl-Neelsen than with other formalin-ether or -ethyl acetate extraction methods. Oocyst numbers g-1 of faeces rose from days 3 to 5 to a first and highest peak lasting to days 7-9, and 5 of the 6 dogs passed oocysts for at least 80 days. However, the numbers of oocysts detected in the dogs' faeces were low, only 16.1% of the samples in the first month after infection and 2.5% thereafter contained greater than or equal to 10 000 oocysts g-1 of faeces. Oocyst production was cyclical, with 19.3% of samples negative in the first month after infection and 42.5% thereafter.
Descriptors: cryptosporidium-parvum, oocysts, viability, survival, alcoholic-beverages,
beverages, tap-water, microbial-contamination, morphology, nonalcoholic-beverages,
Abstract: Cryptosporidium parvum is an enteric coccidian protozoan which produces an environmentally stable oocyst that is excreted in the feces of infected individuals. There have been ten documented waterborne outbreaks in North America. If food or beverages were prepared from contaminated water, that food or beverage would also be a hazard. The objective of this study was to evaluate the survival of Cryptosporidium parvum in beverages. Viability of oocysts as determined by morphology decreased over 24 h exposure in carbonated beverages. Uptake of vital dyes indicated a loss of > 85% of oocyst viability in beer or cola stored at 4C. Loss of viability in tap water, orange juice or infant formula was less than or equal to 35%. It is likely that the low ph of the carbonated beverages was involved in the loss of oocyst viability and premature excystation of the sporozoites.
Abstract: Oysters were placed in an aquarium containing artificial seawater, and Cryptosporidium parvum oocysts were added. Oocysts were later found in the gill washings, hemocytes, and gut contents of the oysters. Hemocytes containing oocysts were intubated into four mice. C. parvum stages developed in the ileal epithelia of all of the mice, indicating that the oocysts in the hemocytes remained infective.
Descriptors: vegetables, cryptosporidium, fresh-products, incidence, oocytes, fecal-coliforms,
Abstract: In Costa Rica, a total of 640 samples from eight different vegetables used for raw consumption were analyzed for the presence of Cryptosporidium spp. oocysts, fecal coliforms, and Escherichia coli Cryptosporidium spp. oocysts were found in 5.0% (4 samples) of cilantro leaves, 8.7% (7 samples) of cilantro roots and 2.5% (2 samples) of lettuce samples. A 1.2% contamination rate was detected in samples of other vegetables (radish, tomato, cucumbers and carrot). Oocysts of this parasite were absent from cabbage. A greater percentage of positive samples was found during the rainy season, and only in cilantro roots and lettuce was a positive linear correlation (P < 0.05) established between the presence of Cryptosporidium spp. oocysts and fecal coliforms and E. coli.
Descriptors: cryptosporidium-parvum, incidence, dna-probes, literature-reviews, detection,
polymerase-chain-reaction, foodborne-diseases, food-contamination, disease-control, oocysts.
Abstract: The role of Cryptosporidium parvum as a foodborne pathogen has not been well documented. Epidemiological features of this parasitic protozoon lead to the assumption that the incidence of cryptosporidiosis due to contaminated food is under-estimated. The high prevalence of C. parvum among dairy herds has increased the spread of oocysts in the farm environment, and their potential presence in raw milk and other raw foods. In October 1993, the first well-documented foodborne outbreak was reported in Maine, USA, and was caused by contaminated hand-pressed apple cider. Although various cases of cryptosporidiosis among humans have pointed to raw milk and other raw foods as possible sources of infection, a conclusive demonstration of foodborne cryptosporidiosis has rarely been established. The limited numbers of oocysts in the suspected samples and the lack of sensitive detection methods adapted for oocyst detection in food contribute to this under-reporting. This review paper discusses various aspects of Cryptosporidium spp. and cryptosporidiosis, including the routes of transmission, the control of oocysts in food, and the available detection methods. The polymerase chain reaction (PCR) combined with DNA probe hybridization is a promising detection method. Recent knowledge on the molecular biology of the parasite for the development of new PCR assays and their potential use in the detection of C. parvum in food are described.
Descriptors: horses, foals, oocytes, cryptosporidiosis, risk-factors, diseases, disease-prevalence, texas, oocyt-shedding.
Descriptors: giardia, cryptosporidium, cysts, oocysts, water-pollution, drinking-water, surveys,
sewage, water, viability, isoenzymes, karyotypes, chromosomes, ribosomal-dna,
nucleotide-sequences, surface-water, giardiasis, gerbils, Ontario, Newfoundland, Manitoba,
Yukon Territory, raw-water
Abstract: This study was carried out to estimate the prevalence and potential for human infectivity of Giardia cysts in Canadian drinking water supplies. The presence of Cryptosporidium oocysts was also noted, but isolates were not collected for further study. A total of 1,760 raw water samples, treated water samples, and raw sewage samples were collected from 72 municipalities across Canada for analysis, 58 of which treat their water by chlorination alone. Giardia cysts were found in 73% of raw sewage samples, 21% of raw water samples, and 18.2% of treated water samples. There was a trend to higher concentration and more frequent incidence of Giardia cysts in the spring and fall but positive samples were found in all seasons. Cryptosporidium oocysts were found in 6.1% of raw sewage samples, 4.5% of raw water samples, and 3.5% of treated water samples. Giardia cyst viability was assessed by infecting Mongolian gerbils (Meriones unguiculatus) and by use of a modified propidium iodide dye exclusion test, and the results were not always in agreement. No Cryptosporidium isolates were recovered from gerbils, but 8 of 276 (3%) water samples and 19 of 113 (17%) sewage samples resulted in positive Giardia infections. Most of the water samples contained a low number of cysts, and 12 Giardia isolates were successfully recovered from gerbils and cultured. Biotyping of these isolates by isoenzyme analysis and karyotyping by pulsed-field gel electrophoresis separated the isolates into the same three discrete groups. Karyotyping revealed four or five chromosomal bands ranging in size from 0.9 to 2 Mb, and four of the isolates had the same banding pattern as that of the WB strain. Analysis of the. nucleotide sequences of the 16S DNA coding for rRNA divided the isolates into two distinct groups corresponding to the Polish and Belgian designations found by other investigators. The occurrence of these biotypes and karyotypes appeared to be random and was not related to geographic or other factors (e.g., different types were found in both drinking water and sewage from the same community). Biotyping and karyotyping showed that isolates from this study were genetically and biochemically similar to those found elsewhere, including well-described human source strains such as WB. We conclude that potentially human-infective Giardia cysts are commonly found in raw surface waters and sewage in Canada, although cyst viability is frequently low. Cryptosporidium oocysts are less common in Canada. An action level of three to five Giardia cysts per 100 liters in treated drinking water is proposed on the basis of the monitoring data from outbreak situations. This action level is lower than that proposed by Haas and Rose for Cryptosporidium spp. ( 10 to 30 oocysts per 100 liters).
Descriptors: horses, cryptosporidium-parvum, giardia-duodenalis, feces, shedding, estimation, horse-riding, amenity-and-recreation-areas, contamination, california.
Descriptors: peptides, immunization, disease-prevention, immunity, vitamin-deficiencies, vitamin-e, retroviridae, viral-diseases, cryptosporidium, cryptosporidium-parvum, resistance, protozoal-infections, intestinal-mucosa, cell-division, spleen-cells, natural-killer-cells, cytotoxicity, phospholipids, lymph-nodes, weight, body-weight, spleen, heart, lipid-peroxidation, b-lymphocytes, t-lymphocytes, cytokines, survival, mice, animal-models.
Descriptors: cryptosporidium-parvum, acetate-coa-ligase, genes, nucleotide-sequences, amino-acid-sequences, molecular-sequence-data, genbank, u24082.
Descriptors: polymerase-chain-reaction, random-amplified-polymorphic-dna, North Dakota.
Abstract: Asian freshwater clams, Corbicula fluminea, exposed for 24 h to 38 liters of water contaminated with infectious Cryptosporidium parvum oocysts (1.00 x 10(6) oocysts/liter; approximately 1.9 x 10(5) oocysts/clam) were examined (hemolymph, gills, gastrointestinal [GI] tract, and feces) on days 1, 2, 3, 7, and 14 postexposure (PE). No oocysts were detected in the water 24 h after the contamination event. The percentage of oocyst-containing clams varied from 20 to 100%, depending on the type of tissue examined and the technique used -- acid-fast stain (AFS) or immunofluorescent antibody (IFA). The oocysts were found in clam tissues and feces on days 1 through 14 PE; the oocysts extracted from the tissues on day 7 PE were infectious for neonatal BALB/c mice. Overall, the highest number of positive samples was obtained when gills and GI tracts were processed with IFA (prevalence, 97.5%). A comparison of the relative oocyst numbers indicated that overall, 58.3% of the oocysts were found in clam tissues and 41.7% were found in feces when IFA was used; when AFS was used, the values were 51.9 and 48.1%, respectively. Clam-released oocysts were always surrounded by feces; no free oocysts or oocysts disassociated from fecal matter were observed. The results indicate that these benthic freshwater clams are capable of recovery and sedimentation of waterborne C. parvum oocysts. To optimize the detection of C. parvum oocysts in C. fluminea tissue, it is recommended that gill and GI tract samples be screened with IFA (such as that in the commercially available MERIFLUOR test kit).
Descriptors: cryptosporidium-parvum, escherichia-coli, drinking-water, beef-cattle, dairy-cattle, foodborne-diseases, waterborne-diseases, food-safety, disease-prevention, disease-transmission, USA.
Descriptors: cryptosporidium, water-pollution, rangelands, cattle, grazing, land-management, legislation, drinking-water, california, san-franciso-public-utilities-commission.
Abstract: We recently described a reverse transcription-PCR (RT-PCR) for detecting low numbers of viable Cryptosporidium parvum oocysts spiked into clarified environmental water concentrates. We have now modified the assay for direct analysis of primary sample concentrates with simultaneous detection of viable C. parvum oocysts, Giardia cysts, and a novel type of internal positive control (IPC). The IPC was designed to assess both efficiency of mRNA isolation and potential RT-PCR inhibition. Sensitivity testing showed that low numbers of organisms, in the range of a single viable cyst and oocyst, could be detected when spiked into 100-microliters packed pellet volumes of concentrates from creek and river water samples. The RT-PCR was compared with an immunofluorescence (IF) assay by analyzing 29 nonspiked environmental water samples. Sample volumes of 20 to 1,500 liters were concentrated with a wound fiberglass cartridge filter. Frequency of detection for viable Giardia cysts increased from 24% by IF microscopy to 69% by RT-PCR. Viable C. parvum oocysts were detected only once by RT-PCR (3%) in contrast to detection of viable Cryptosporidium spp. in four samples by IF microscopy (14%), suggesting that Cryptosporidium species other than C. parvum were present in the water. This combination of the large-volume sampling method with RT-PCR represents a significant advance in terms of protozoan pathogen monitoring and in the wider application of PCR technology to this field of microbiology.
Descriptors: cryptosporidium-parvum, oocysts, measurement, flow-cytometry, viability, comparisons, microscopy, cattle-dung, excysted-oocytes.
Descriptors: cryptosporidium-parvum, oocysts, immunofluorescence.
Descriptors: cryptosporidium-parvum, dna, extraction, polymerase-chain-reaction, detection, feces, cattle, dna-hybridization, comparisons, enzyme-immunoassay.
Descriptors: calves, cryptosporidium-parvum, experimental-infections, cryptosporidiosis, antibody-formation, iga, igm, interferon, leukocytes, humoral-immunity, cell-mediated-immunity.
Descriptors: cryptosporidium-parvum, Georgia.
Descriptors: calves, cryptosporidium-parvum, diarrhea, inactivated-vaccines, colostral-immunity,
cell-mediated-immunity, oocysts, experimental-infections.
Abstract: Cryptosporidium parvum is a protozoan parasite that is now recognized as one of the leading causes of diarrhea in young calves. To date, there are no drugs or preventive measures available for the control of this disease. We have developed an oral vaccine that, when given to calves at birth, protects against experimental challenge with C. parvum. However, when field tested on a large dairy operation with heavy endemic C. parvum infection, the vaccine failed to provide protection. The difference in these results is most likely due to uncontrolled early (probably within hours of birth) exposure to C. parvum on the farm versus controlled exposure at 1 wk of age in the experimental trials. The successful control of C. parvum in the field may require vaccines that generate a rapid (within the first few days of life) cell-mediated immune response in the calf. Successful use of such a vaccine will also require improved hygiene and management practices to minimize the exposure of calves to C. parvum in the initial days of life, thus allowing time for protective immune responses to be generated. Careful attention to hygiene in the management of sick calves is also critical to minimize the spread of the parasite to other animals.
Descriptors: giardia, cryptosporidium, water-pollution, microbial-contamination, surface-water,
watersheds, cattle, feces, infectivity, giardiasis, gerbils, biotypes, geographical-variation, British
Abstract: Two adjacent British Columbia, Canada, watersheds with similar topographical features were studied. Both the Black Mountain Irrigation District (BMID) and the Vernon Irrigation District (VID) serve rural agricultural communities which are active in cattle ranching. The present study was carried out in five phases, during which a total of 249 surface water samples were tested in the study watersheds. The aims of these phases were to determine levels of parasite contamination in raw water samples collected from the intakes as well as from other sites in each watershed and to investigate cattle in the watersheds as potential sources of parasite contamination of surface drinking water supplies. Giardia cysts were not detected in the raw water samples collected from lake sources at the headwaters of both watersheds but were found in 100% (70 of 70) of water samples collected at the BMID intake and 97% (68 of 70) of water samples collected at the VID intake. Significantly higher levels (P < 0.05) of Giardia cysts were found at the BMID intake (phase 1, 7 to 2,215 cysts per l00 liters; phase 3, 4.6 to 1,880 cysts per 100 liters) when compared with that of the VID intake (2 to 114 cysts per 100 liters). The BMID watershed has a more complex system of surface water sources than the VID watershed. Cattle have access to creeks in the BMID watershed, whereas access is restricted in the VID watershed. Collection of raw water samples from a creek upstream and downstream of a cattle ranch in the BMID watershed showed that the downstream location had significantly higher (P < 0.05) levels (0.6 to 42.9 cysts per 100 liters and 1.4 to 300.0 oocysts per 100 liters) of both Giardia. cysts and Cryptosporidium oocysts than those of the upstream location (0.5 to 34.4 cysts per 100 liters and 0.5 to 34.4 oocysts per 100 liters). Peak concentrations of both parasites coincided with calving activity. Fecal samples, collected from cattle in both watersheds, showed 10% (3 of 30) in the BMID and 50% (5 of 10) in the VID watersheds to be Giardia positive. No Cryptosporidium-positive fecal samples were found. Giardia cysts isolated from the BMID watershed were repeatedly infective to gerbils in contrast to those from the VID watershed. The 10 BMID drinking water Giardia isolates retrieved into culture and biotyped showed zymodeme and karyotype heterogeneity. The differences in patterns of parasite contamination and cattle management practices contribute to the unique watershed characteristics observed between two areas which are topographically similar and geographically adjacent.
Descriptors: cryptosporidiosis, cryptosporidium, disease-surveys, zoonoses, farm-workers, seasonal-variation, disease-prevalence, epidemiology, cattle, goats, pigs, quails, feces, laboratories, South Carolina.
Descriptors: zoo-animals, carnivores, bovidae, giraffa-camelopardalis, ceratotherium-simum, cryptosporidium, cryptosporidiosis, new-host-records, disease-prevalence, disease-surveys, Spain.
Descriptors: cryptosporidium, giardia, infections, marmosets, disease-vectors, disease-surveys, disease-carriers.
Abstract: Oocysts of Cryptosporidium parvum placed in artificial seawater at salinities of 10, 20, and 30 ppt at 10 degrees C and at 10 ppt at 20 degrees C were infectious after 12 weeks. Those placed in seawater at 20 ppt and 30 ppt at 20 degrees C were infectious for 8 and 4 weeks, respectively. These findings suggested that oocysts could survive in estuarine waters long enough to be removed by filter feeders such as oysters. Thereafter, 30 Eastern oysters, Crassostrea virginica, were collected with a dredge or with hand tongs at each of six sites within Maryland tributaries of the Chesapeake Bay in May and June and in August and September of 1997. Hemocytes and gill washings from all oysters were examined for the presence of Cryptosporidium oocysts and Giardia cysts by immunofluorescence microscopy utilizing a commercially available kit containing fluorescein isothiocyanate-conjugated monoclonal antibodies. Giardia was not detected by this method from any of the 360 oysters examined. Presumptive identification of Cryptosporidium oocysts was made in either hemocytes or gill washings of oysters from all six sites both times that surveys were conducted. In addition, during August and September, for each of the six sites, hemocytes from the 30 oysters were pooled and gill washings from the oysters were pooled. Each pool was delivered by gastric intubation to a litter of neonatal mice to produce a bioassay for oocyst infectivity. Intestinal tissue from two of three mice that received gill washings from oysters collected at a site near a large cattle farm and shoreline homes with septic tanks was positive for developmental stages of C. parvum. These findings demonstrate for. the first time that oysters in natural waters harbor infectious C. parvum oocysts and can serve as mechanical vectors of this pathogen.
Abstract: A new viability assay for Cryptosporidium and Eimeria sporozoites is described. It involves the use of both acridine orange and bis-benzimide and is more rapid, easier and less subjective than procedures used previously. The assay has been used to investigate the effects of respiratory inhibitors and pH on the sporozoites of C. parvum, C. muris and E. tenella. Neither cyanide nor azide reduced the viability of C. parvum or E. tenella, whereas they had some effect on C. muris. This latter organism, an intracellular parasite of stomach epithelial cells, also differed from the other two in being able to survive pH 2 for as long as 1 h.
Descriptors: cryptosporidium-parvum, oocytes, movement-in-soil, transport-processes,
monitoring, soil-profiles, losses-from-soil, runoff, water-pollution, risk, animal-wastes,
application-to-land, dispersal, spread, parasites, simulation, apparatus.
Abstract: A novel greenhouse based soil tilting table apparatus was used to investigate the potential for movement of the protozoan pathogen Cryptosporidium parvum both through and across a low permeability soil following the application of contaminated livestock waste to land. Soil blocks supported at an angle of 7.5% by the soil table were inoculated at one end with oocyst seeded slurry and subsequently irrigated at regular intervals over a 70-day period. Movement of the pathogen in runoff was demonstrated for at least 21 days and in one case in excess of 70 days from the time of inoculation. Water was also lost following percolation down through the soil profile and significant numbers of oocysts were also lost via this route average numbers leached decreasing from 8.36 +/- 0.56 X 10(6) at day 1 to 2.27 +/- 0.73 x 10(4) at day 70. At the end of the study cores were removed from the soil blocks to determine the location of oocysts remaining within the soil. Numbers decreased down through the soil profile and as the distance from the point of inoculation increased so that 70 cm from the point of inoculation no oocysts could be detected in the soil at any depth. This implies that oocysts contained in runoff stay in the aqueous phase and do not precipitate out onto the soil surface, suggesting that even if the distances travelled are increased there may still be a significant pollution threat.
Descriptors: eimeria, trypanosoma, babesia, plasmodium, cryptosporidium, toxoplasma,
leishmania, protozoal-infections, vaccines, life-cycle, vaccine-development, literature-reviews.
Abstract: Protozoan parasites are important animal and human pathogens. At present, most of these infections are controlled by chemotherapy. In addition, vaccines are available for some of these diseases. There is, however, still an urgent need for the development of vaccines against protozoal diseases, since the current array of available vaccines is very limited. This review describes the different approaches that have been taken to develop such vaccines and discusses the difficulties that hampered vaccine development. Many of the problems are related to the complex life cycle of these parasites and the virtual lack of mass in vitro culture systems. We also give an overview of the commercial and non-commercial vaccines that do exist at present. Finally, we describe the future directions of this interesting field. New techniques and strategies include parasite cultivation methods and recombinant-DNA techniques, such as vector vaccines and DNA-vaccines. Moreover, these approaches are complemented by the development of sophisticated adjuvants; the coupling of immunoprotective molecules to entities with adjuvant activity or the use of cytokines, e.g. IL-12. Through these innovations new vaccines against protozoal diseases will become available in the near future.
Descriptors: anas-platyrhynchos, cryptosporidium-parvum, oocysts, experimental-infections,
defecation, feces, viability, infectivity, mice, disease-vectors, immunofluorescence,
animal-models, waterfowl, oocyst-shedding.
Abstract: Six Cryptosporidium-free Peking ducks (Anas platyrhynchos) were each orally inoculated with 2.0 X 10(6) Cryptosporidium parvum oocysts infectious to neonatal BALB/c mice. Histological examination of the stomachs jejunums, flea, ceca, cloacae, larynges, tracheae, and lungs of the ducks euthanized on day 7 postinoculation (p.i.) revealed no life-cycle stages of C. parvum. However, inoculum-derived oocysts extracted from duck feces established severe infection in eight neonatal BALB/c mice (inoculum dose, 2.5 X 10(5) per mouse). On the basis of acid-fast stained direct wet smears, 73% of the oocysts in duck feces were intact (27% were oocyst shells), and their morphological features conformed to those of viable and infectious oocysts of the original inoculum. The fluorescence scores of the inoculated oocysts, obtained by use of the MERIFLUOR test, were identical to those obtained for the feces-recovered oocysts (the majority were 3+ to 4+). The dynamics of oocyst shedding showed that the birds released a significantly higher number of intact oocysts than the oocyst shells (P < 0.01). The number of intact oocysts shed (87%) during the first 2 days p.i. was significantly higher than the number shed during the remaining 5 days p.i. (P < 0.01) and significantly decreased from day 1 to day 2 p.i. (P < 0.01). The number of oocyst shells shed during 7 days p.i. did not vary significantly (P > 0.05). The retention of infectivity of C. parvum oocysts after intestinal passage through an aquatic bird has serious epidemiological and epizootiological implications. Waterfowl may serve as mechanical vectors for the waterborne oocysts and may enhance contamination of surface waters with C. parvum. As the. concentration of Cryptosporidium oocysts in source waters is attributable to watershed management practices, the watershed protection program should consider waterfowl as a potential factor enhancing contamination of the source water with C. parvum.
Abstract: The survival of Cryptosporidium parvum during ensilage of perennial ryegrass was examined in laboratory silos with herbage prepared in one of three different ways; either untreated, inoculated with a strain of Lactobacillus plantarum or by direct acidification with formic acid. The pH values of all silages initially fell below 4.5, but only formic acid-treated silage remained stable at less than pH 4 after 106 d, with the pH of the untreated and inoculant-treated silages rising to above 6. The formic acid-treated silage had a high lactic acid concentration (109 g kg-1 dry matter (DM)) and low concentrations of propionic and butyric acids after 106 d. However, the untreated and inoculant-treated silages showed an inverse relationship, with low lactic acid concentrations and high concentrations of acetic, propionic and butyric acids. These silages also contained ammonia-N concentrations in excess of 9 g kg-1 DM. In terms of the viability of Cryptosporidium parvum oocysts very few differences were seen after 14 d of ensilage with ca 50% remaining viable, irrespective of treatment and total numbers had declined from the initial level of 5.9 X 10(4) to 1 X 10(4) g-1 fresh matter. Total oocyst numbers remained approximately the same until the end of the ensiling period, with the percentage of viable oocysts declining to 46, 41 and 32% respectively for formic acid, inoculant and untreated silages. The results are discussed in terms of changes occurring during the silage fermentation, in particular the products which may influence the survival of Cryptosporidium and implications for agricultural practice and the health of silage fed livestock.
Descriptors: cryptosporidium, sporozoites, cytoplasm, rna, complementary-dna, clones, nucleotide-sequences, amino-acid-sequences, comparisons, rna-polymerase, enzyme-activity, viral-rna-dependent-rna-polymerase, uncapsidated-dsrna, genbank, u95995, genbank, u95996, molecular-sequence-data, sequence-homology.
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