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

摘要

In eastern chipmunks (Tamias striatus) inoculated intramuscularly with 10^1.5 to 10^5.7 PFU of West Nile virus (WNV), serum titers developed sufficient to infect Aedes triseriatus (Say), Ae. vexans (Meigen), and Culex pipiens (L.). Mean titers (95% confidence interval) of 8 chipmunks were 10^{3.9(3.3–4.5)}, 10^{6.7(6.4–7.0)}, and 10^{5.8(4.1–7.5)} PFU/mL on days 1–3 postinoculation (p.i.) and 10^5.8 PFU/mL in 1 chipmunk on day 4 p.i. Mean estimated days that WNV titers were >10^4.8 and >10^5.6 were 1.7 (1.1–2.3) and 1.4 (1.0–1.6). The longest period of viremia >10^4.8 PFU/mL was 3–4 days. WNV antigen was detected in the small intestine of 2 chipmunks and the kidneys of 4 chipmunks by immunohistochemistry. WNV also was detected in urine, saliva, and feces of some chipmunks. These data suggest chipmunks might play a role in enzootic WNV cycles and be an amplifying host for mosquitoes that could infect humans.