Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2000
Publication Date: 12/1/2000
Interpretive Summary: In the fall of 1999, West Nile virus (WNV) was transmitted from infected mosquitos to birds and animals. This resulted in neurologic disease in humans, horses, and wild and zoological birds in the northeast USA. Turkeys could be a potential host for WNV because of high density turkey farming and the presence of large wild turkey populations along the eastern nseaboard of the U.S.A. However, little is known about the ability of WNV t infect domestic or wild turkeys. Experimental inoculation of WNV into turkeys failed to produce clinical disease, but low levels of the virus were present in the blood. These blood levels were too low to efficiently infect mosquitos. In addition, WNV could not be transmitted to other turkeys by contact with infected birds. Such data suggest WNV will not be a new disease of turkeys, and turkeys will not be a significant source for infecting mosquitos. Wild birds will be the primary source of WNV for mosquitos.
Technical Abstract: In the fall of 1999, mosquito-transmitted West Nile virus (WNV) was isolated during an outbreak of neurologic disease in humans, horses, and wild and zoological birds in the northeast USA. Turkeys could be a potential reservoir for WNV because of high density turkey farming and the presence of large wild turkey populations in the eastern seaboard of the U.S.A. Little is known about the pathogenicity of WNV in domestic or wild turkeys. Specific-pathogen-free 3-week-old turkeys were inoculated subcutaneously with WNV. No clinical signs were observed in the turkeys over the 21 days of the experiment, but one turkey died abruptly on 8 days post-inoculation (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 was not 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. These data suggest WNV lacks the potential to be a major new disease of turkeys, and turkeys will not be a significant amplifying host for infecting mosquitos.