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Abutarbush SM O'Connor BP Clark C Sampieri F Naylor JM 《The Canadian veterinary journal. La revue veterinaire canadienne》2004,45(4):315-317
Two horses had a history of ataxia and weakness or recumbency. One recovered and was diagnosed with West Nile virus (WNV) infection by serologic testing. The other was euthanized; it had meningoencephalomyelitis, WNV was detected by polymerase chain reaction. West Nile virus infection is an emerging disease. Year 2002 is the first year in which cases have been seen in Saskatchewan. 相似文献
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West Nile Virus (WNV) infection manifests itself clinically a nd pathologically differently in various species of birds. The clinicopathologic findings and WNV antigen tissue distribution of six great gray owls (Strix nebulosa) and two barred owls (Strix varia) with WNV infection are described in this report. Great gray owls usually live in northern Canada, whereas the phylogenetically related barred owls are native to the midwestern and eastern United States and southern Canada. Naturally acquired WNV infection caused death essentially without previous signs of disease in the six great gray owls during a mortality event. Lesions of WNV infection we re dominated by hepatic and splenic necrosis, with evidence o f disseminatedintravascular coagulation in the great gray owls. WNV antigen was widely distributed in th e organs of the great gray owls and appeared totarget endothelial cells, macrophages, and hepatocytes. The barred owls represented two sporadic cases. They had neurologic disease with mental dullness that led to euthanasia. These birds had mild to moderate lymphoplasmacytic encephalitis with glial nodules and lymphoplasmacytic pectenitis. WNV antigen was sparse in barred owls and only present in a few brain neurons and renaltubular epithelial cells. The cause of the different manifestations of WNV disease in these fairly closely related owl species is uncertain. 相似文献
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J Bingham RA Lunt DJ Green KR Davies V Stevens FYK Wong 《Australian veterinary journal》2010,88(6):204-210
Objective To study the potential role of an Australian corvid, the little raven (Corvus mellori), in the surveillance for exotic West Nile virus (WNV) in Australia. Method In a series of trials, little ravens were infected with WNV (strain 4132 New York 1999) and Kunjin virus (strain K42886) by the intramuscular route. They were observed for 20 days during which blood and swab samples were taken for virus isolation. Tissue samples were taken from ravens humanely killed during the acute infection period, and at the termination of the trials, for virus isolation, histopathology and immunohistochemistry. Results Ravens infected with WNV became mildly ill, but all recovered and seroconverted. Blood virus titres peaked around 3 to 4 days after inoculation at levels between 103.0 to 107.5 plaque forming units/mL. Virus or viral antigen was detected in spleen, liver, lung, kidney, intestine, testis and ovary by virus isolation and/or immunohistochemistry. WNV was detected in oral and cloacal swabs from 2 to 7 days post inoculation. The molecular and pathogenic characteristics of the inocula were consistent with them being of high virulence, as expected for this isolate. Ravens infected with Kunjin virus developed viraemia and seroconverted, although they did not develop disease. Conclusions Little ravens do not develop severe disease in response to virulent WNV infection and for this reason may not be important sentinel hosts in the event of an outbreak of WNV, as in North America. However, as they have relatively high viraemias, they may be able to support virus cycles. 相似文献
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Isabelle Lanthier Michel Hébert Donald Tremblay Josée Harel André D Dallaire Christiane Girard 《Journal of veterinary diagnostic investigation》2004,16(4):326-329
A case of West Nile virus (WNV) infection in a captive 4-month-old Arctic wolf (Canis lupus) is described. The animal had vomiting, anorexia, and ataxia before death. Histopathology revealed multifocal severe renal lymphoplasmacytic vasculitis, mostly affecting small arterioles, with fibrinoid degeneration of some vessel walls. Many small foci of gliosis were detected in the cerebral cortex. West Nile virus was demonstrated in the kidneys and cerebrum by immunohistochemistry and polymerase chain reaction. The described renal changes represent a novel pathological finding of WNV infection. 相似文献
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Eastern Screech Owls (EASOs) were experimentally infected with the pathogenic New York 1999 strain of West Nile virus (WNV) by subcutaneous injection or per os. Two of nine subcutaneously inoculated birds died or were euthanatized on 8 or 9 days postinfection (DPI) after <24 hr of lethargy and recumbency. All subcutaneously inoculated birds developed levels of viremia that are likely infectious to mosquitoes, with peak viremia levels ranging from 10(5.0) to 10(9.6) plaque-forming units/ml. Despite the viremia, the remaining seven birds did not display signs of illness. All birds alive beyond 5 DPI seroconverted, although the morbid birds demonstrated significantly lower antibody titers than the clinically normal birds. Cagemates of infected birds did not become infected. One of five orally exposed EASOs became viremic and seroconverted, whereas WNV infection in the remaining four birds was not evident. All infected birds shed virus via the oral and cloacal route. Early during infection, WNV targeted skin, spleen, esophagus, and skeletal muscle. The two morbid owls had myocardial and skeletal muscle necrosis and mild encephalitis and nephritis, whereas some of the clinically healthy birds that were sacrificed on 14 DPI had myocardial arteritis and renal phlebitis. WNV is a significant pathogen of EASOs, causing pathologic lesions with varying clinical outcomes. 相似文献
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Gardner IA Wong SJ Ferraro GL Balasuriya UB Hullinger PJ Wilson WD Shi PY MacLachlan NJ 《Veterinary research》2007,38(1):109-116
A prospective cohort study was used to estimate the incidence of West Nile virus (WNV) infection in a group of unvaccinated horses (n = 37) in California and compare the effects of natural WNV infection in these unvaccinated horses to a group of co-mingled vaccinated horses (n = 155). Horses initially were vaccinated with either inactivated whole virus (n = 87) or canarypox recombinant (n = 68) WNV vaccines during 2003 or 2004, prior to emergence of WNV in the region. Unvaccinated horses were serologically tested for antibodies to WNV by microsphere immunoassay incorporating recombinant WNV E protein (rE MIA) in December 2003, December 2004, and every two months thereafter until November 2005. Clinical neurologic disease attributable to WNV infection (West Nile disease (WND)) developed in 2 (5.4%) of 37 unvaccinated horses and in 0 of 155 vaccinated horses. One affected horse died. Twenty one (67.7%) of 31 unvaccinated horses that were seronegative to WNV in December, 2004 seroconverted to WNV before the end of the study in November, 2005. Findings from the study indicate that currently-available commercial vaccines are effective in preventing WND and their use is financially justified because clinical disease only occurred in unvaccinated horses and the mean cost of each clinical case of WND was approximately 45 times the cost of a 2-dose WNV vaccination program. 相似文献
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In the fall of 1999, West Nile virus (WNV) was isolated during an outbreak of neurologic disease in humans, horses, and wild and zoological birds in New York, Connecticut, and New Jersey. Turkeys could potentially be a large reservoir for WNV because of the high-density turkey farming and the presence of large wild turkey populations in the eastern seaboard of the United States. Little is known about the pathogenicity of WNV in domestic or wild turkeys. Specific-pathogen-free 3-wk-old turkeys were inoculated subcutaneously with 10(3.3) mean tissue culture infective doses of a WNV strain isolated fromthe index case in a New York crow. No clinical signs were observed in the turkeys over the 21 days of the experiment. One turkey died abruptly at 8 days postinoculation (DPI). Many turkeys developed viremia between 2 and 10 DPI, but the average level of virus was very low, less than needed to efficiently infect mosquitos. Low levels of WNV were detected in feces on 4 and 7 DPI, but no virus was isolated from oropharyngeal swabs. WNV wasnot transmitted from WNV-inoculated to contact-exposed turkeys. All WNV-inoculated poults seroconverted on 7 DPI. In the turkey that died, WNV was not isolated from intestine, myocardium, brain, kidney, or cloacal and oropharyngeal swabs, but sparse viral antigen was demonstrated by immunohistochemistry in the heart and spleen. Turkeys in contact with WNV-inoculated turkeys and sham-inoculated controls lacked WNV specific antibodies,and WNV was not isolated from plasma and cloacal and oropharyngeal swabs. These data suggest that WNV lacks the potential to be a major new disease of turkeys and that turkeys will not be a significant amplifying host for infecting mosquitos. 相似文献
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In the fall of 1999, West Nile virus (WNV) was isolated for the first time in the Western Hemisphere during an outbreak of neurologic disease in humans, horses, and wild and zoo birds in the northeastern United States. Chickens are a potential reservoir for WNV, and little is known about the pathogenicity of WNV in domestic chickens. Seven-week-old chickens derived from a specific-pathogen-free flock were inoculated subcutaneously with 1.8 x 10(3) 50% tissue culture infectious dose of a crow isolate of WNV in order to observe clinical signs and evaluate the viremic phase, gross and microscopic lesions, contact transmission, and immunologic response. There were no observable clinical signs in the WNV-inoculated chickens during the 21-day observation period. However, histopathologic examination of tissues revealed myocardial necrosis, nephritis, and pneumonitis at 5 and 10 days postinoculation (DPI); moderate to severe nonsuppurative encephalitis also was observed in brain tissue from one of four inoculated birds examined at 21 DPI. WNV was recovered from blood plasma for up to 8 DPI. Virus titers as high as 10(5)/ml in plasma were observed at 4 DPI. Fecal shedding of virus was detected in cloacal swabs on 4 and 5 DPI only. The WNV also was isolated from myocardium, spleen, kidney, lung, and intestine collected from chickens euthanatized at 3, 5, and 10 DPI. No virus was isolated from inoculated chickens after 10 DPI. Antibodies specific to WNV were detected in inoculated chickens as early as 5 DPI by the plaque reduction neutralization test and 7 DPI by the indirect fluorescent antibody test. Chickens placed in contact with inoculated chickens at 1 DPI lacked WNV-specific antibodies, and no WNV was isolated from their blood plasma or cloacal swabs throughout the 21 days of the experiment. 相似文献
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Crows have been the centerpiece of avian West Nile virus (WNV) surveillance and research in North America. This work has demonstrated variation in susceptibility to WNV infection between American (Cor vus brachyrhynchos) andFish Crows (Corvus ossifragus). The higher WNV-associated mortality rate in American Crows compared with Fish Crows suggests that WNV antibody prevalence would be greater in the Fish Crow population. The objectives of this study were to 1) determine whether Fish Crows had higher WNV antibody prevalencethan American Crows, 2 ) determine th e persistence o f antibodies to WNV in naturally infected Fish Crows, and 3) develop a technique to distinguish Fish Crows from American Crows on the basis of sequence analysis and restriction enzyme digestion of a mitochondrial DNA fragment. West Nile virus antibody prevalence was 16.5% (n = 97) in Fish Crows and 5.7% in American Crows (n = 53) collected from Georgia between 2004 and 2006. Antibodies persisted at high titers for 12 mo in Fish Crows. This is the first report of WNV antibody persistence in a crow species. A polymerase chain reaction technique paired with restriction enzyme digestion easily distinguished American Crows from Fish Crows on the basis of a mitochondrial DNA fragment. 相似文献
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ABSTRACT: West Nile virus (WNV) is a positive-stranded RNA virus belonging to the Flaviviridae family, a large family with 3 main genera (flavivirus, hepacivirus and pestivirus). Among these viruses, there are several globally relevant human pathogens including the mosquito-borne dengue virus (DENV), yellow fever virus (YFV), Japanese encephalitis virus (JEV) and West Nile virus (WNV), as well as tick-borne viruses such as tick-borne encephalitis virus (TBEV). Since the mid-1990s, outbreaks of WN fever and encephalitis have occurred throughout the world and WNV is now endemic in Africa, Asia, Australia, the Middle East, Europe and the Unites States. This review describes the molecular virology, epidemiology, pathogenesis, and highlights recent progress regarding diagnosis and vaccination against WNV infections. 相似文献