West Nile Virus Viremia in Eastern Chipmunks (Tamias striatus) Sufficient for Infecting Different Mosquitoes

Abstract

Chipmunks might play a role in enzootic WNV cycles and be an amplifying host for mosquitoes that infect humans.

Arboviruses in North Dakota, 2003–2006

“…It increased to 35.5% and 60.0% in early September. Aedes vexans may become infected by feeding on small or medium-sized mammals, which have been reported to have specific antibodies to WNV, 47 shown to produce viremias sufficient to infect mosquitoes, [48][49][50][51] and found naturally infected in the field. 52 The risk that humans will acquire an infectious bite was greatest from the middle of July through the end of August with transmission still occurring in early September (Supplemental Table 4).…”

Ecology of West Nile Virus Transmission and Its Impact on Birds in the Western Hemisphere

“…In addition, birds are fed on much more frequently than these classes of animals by mosquitoes of the genus Culex that are most frequently infected (Apperson et al 2002(Apperson et al , 2004Kilpatrick et al 2006c, d;Molaei et al 2006;Savage et al 2007). For example, eastern chipmunk (Tamias striatus), the most competent wild mammal studied to date (Platt et al 2007), has not been identifi ed from any of the >2,300 Culex bloodmeals identifi ed in the studies just cited. Similarly, in terms of infectiousness, their competence index was a low 0.36 (Fig.…”

“…Laboratory infection studies to estimate host competence have been published for 44 species of nondomesticated birds in 23 families and 11 orders Reisen et al 2005aReisen et al , b, 2006Reisen et al , 2007aClark et al 2006;Nemeth et al 2006;Owen et al 2006;Reisen and Hahn 2007;Platt et al 2008), 3 species of wild mammals (Tiawsirisup et al 2005b, Root et al 2006, Platt et al 2007, and 5 species of reptiles and one amphibian Komar 2003, Klenk et al 2004). In these experiments, animals are infected by either allowing infectious mosquitoes to feed on them or by an intramuscular or subcutaneous injection of virus.…”

Requirement of Glycosylation of West Nile Virus Envelope Protein for Infection of, but Not Spread within, Culex quinquefasciatus Mosquito Vectors

“…Although small mammals can become infected with WNV and outbreaks in humans and horses regularly occur, mammalian infection is not thought to substantially contribute to viral maintenance in nature. [3][4][5][6][7] The envelope (E) protein of most flaviviruses contains an N-linked glycosylation site at amino acids 153/154; DENV contains a second site at E protein amino acid 67. Glycosylation of the E protein is not required for virion formation or infectivity because naturally non-glycosylated isolates of St. Louis encephalitis virus, yellow fever virus, and WNV have been identified.…”