Abstract
West Nile virus (WNV)-associated deaths of American white pelican (Pelecanus erythrorhynchos) chicks have been recognized at various nesting colonies in the United States since 2002. We evaluated American white pelican nesting colonies in Sheridan County, Montana, USA, for an association between WNV-positive pelican carcasses and human West Nile neuroinvasive disease. Persons in counties hosting affected colonies had a 5x higher risk for disease than those in counties with unaffected colonies. We also investigated WNV infection and blood meal source among mosquitoes and pelican tissue type for greatest WNV detection efficacy in carcasses. WNV-infected Culex tarsalis mosquitoes were detected and blood-engorged Cx. tarsalis contained pelican DNA. Viral loads and detection consistency among pelican tissues were greatest in feather pulp, brain, heart, and skin. Given the risks posed to wildlife and human health, coordinated efforts among wildlife and public health authorities to monitor these pelican colonies for WNV activity are potentially useful.
Highlights
After West Nile virus (WNV; family Flaviviridae, genus Flavivirus) was detected in the Great Plains of the United States in 2002, programs were initiated to identify the spatial distribution of WNV transmission risk throughout the region
We observed an association between human cases of West Nile neuroinvasive disease (WNND) and WNV-induced juvenile pelican deaths in counties with pelican-nesting colonies
The positive and negative predictive values of pelican WNV-associated deaths for human WNND cases were similar in magnitude to those of American crow (Corvus brachyrhynchos) deaths
Summary
After West Nile virus (WNV; family Flaviviridae, genus Flavivirus) was detected in the Great Plains of the United States in 2002, programs were initiated to identify the spatial distribution of WNV transmission risk throughout the region. Concurrent with the arrival of WNV to the northern Great Plains region, high death rates of pelican chicks were observed at 4 major colonies in Montana, North Dakota, South Dakota, and Minnesota. WNV was presumed to be the etiologic agent for >9,000 American white pelican deaths in 7 states in 2002–2003 on the basis of testing of a sample of carcasses from various affected colonies [6]. We collected a series of tissue types from a subset of pelican carcasses at our field site to identify the most efficient tissue for maximizing the probability of WNV detection and to confirm WNV infection as a contributing factor to elevated prefledgling pelican death rates
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