An Outbreak of Eastern Equine Encephalitis Virus in Free-Ranging White-Tailed Deer in Michigan

Abstract

Eastern equine encephalitis (EEE) virus has been recognized as affecting horses and humans in the eastern United States for 70 yr. Evidence of exposure with EEE virus has been reported in a variety of free-ranging wild birds and mammals but cases of clinical disease are much less commonly reported. In Michigan, reports of outbreaks of EEE virus in equine species extend back more than a half century. We report diagnosis of EEE virus infection of multiple free-ranging white-tailed deer (Odocoileus virginianus) from three Michigan counties during late summer of 2005. Infection was confirmed in seven of 30 deer collected based on reported neurologic signs and results from immunohistochemistry, polymerase chain reaction, and/or virus isolation. One of the deer also was infected with West Nile virus and an eighth deer had microscopic lesions in the cerebrum consistent with those reported for EEE. To our knowledge, this is the first report of multiple cases of EEE in free-ranging white-tailed deer, and highlights several issues of significance to wildlife managers and public health officials.

Serological Evidence for Eastern Equine Encephalitis Virus Activity in White-Tailed Deer, Odocoileus virginianus, in Vermont, 2010

“…The overall seropositivity rate of 10.2% in this study is similar to the 14% rate found in Georgia and the 7.1% rate found in Maine in 2010. [17][18][19] Culiseta melanura, the primary enzootic vector, and Coquillettidia, Culex, and Aedes spp., which are likely bridge vectors of EEEV, have previously been documented in Vermont. 9,16 These potential bridge vectors are widely distributed in Vermont, but the distribution of Cs.…”

“…The white-tailed deer has been shown to be a reasonable sentinel species that is frequently exposed to EEEV. [17][18][19][20] White-tailed deer also represent a large proportion of the mammalian source for blood meals for the most common bridge vector species. 21 In addition, white-tailed deer have a summer home range that is about 1 mile in radius, to which they return faithfully.…”

Using Wild White-Tailed Deer to Detect Eastern Equine Encephalitis Virus Activity in Maine

“…This species was selected as a sentinel for several reasons. First, several previous studies in the US (Hoff et al 1973, Bigler et al 1975, Tate et al 2005, Schmitt et al 2007) have reported EEEV antibody-positive sera among populations of free-ranging O. virginianus, demonstrating that deer frequently become infected with EEEV. Second, white-tailed deer form a significant proportion of the blood meals of EEEV bridge vectors, particularly Cq.…”

Encephalitic Development in Alphaviral Infection

“…The virus has been isolated from birds and other mammals such as equines, sheep, cattle, and deer as well as mosquitoes throughout these regions (Carman, et al, 1995;Gibbs, 1976;McGee, et al, 1992;Schmitt, et al, 2007). Cotton rats and house sparrows have been proposed as other hosts for the virus (Arrigo, et al, 2010).…”