Alligators as West Nile Virus Amplifiers

Recent evidence suggests that American alligators (Alligator mississippiensis) may be capable of transmitting West Nile virus (WNV) to other alligators. We experimentally exposed 24 juvenile alligators to WNV parenterally or orally. All became infected, and all but three sustained viremia titers \u3e5.0 log10 PFU/mL (a threshold considered infectious for Culex quinquefasciatus mosquitoes) for 1 to 8 days. Noninoculated tankmates also became infected. The viremia profiles and multiple routes of infection suggest alligators may play an important role in WNV transmission in areas with high population densities of juvenile alligators

West Nile virus transmission in resident birds, Dominican Republic

Centers for Disease Control and Prevention http://www.cdc.gov/ncidod/EID/vol9no10/03-0222.htmWe report West Nile virus (WNV) activity in the Dominican Republic for the first time. Specific anti-WNV antibodies were detected in 5 (15%) of 33 resident birds sampled at one location in November 2002. One seropositive bird was <4 months old, indicating a recent infection

West Nile virus transmission in resident birds, Dominican Republic

Centers for Disease Control and Prevention http://www.cdc.gov/ncidod/EID/vol9no10/03-0222.htmWe report West Nile virus (WNV) activity in the Dominican Republic for the first time. Specific anti-WNV antibodies were detected in 5 (15%) of 33 resident birds sampled at one location in November 2002. One seropositive bird was <4 months old, indicating a recent infection

Alligators as West Nile Virus Amplifiers

Juvenile alligators may help transmit West Nile virus in some areas

SUSCEPTIBILITY OF GREATER SAGE-GROUSE TO EXPERIMENTAL INFECTION WITH WEST NILE VIRUS

Populations of greater sage-grouse (Centrocercus urophasianus) have declined 45– 80% in North America since 1950. Although much of this decline has been attributed to habitat loss, recent field studies have indicated that West Nile virus (WNV) has had a significant negative impact on local populations of grouse. We confirm the susceptibility of greater sage-grouse to WNV infection in laboratory experimental studies. Grouse were challenged by subcutaneous injection of WNV (103.2 plaque-forming units [PFUs]). All grouse died within 6 days of infection. The Kaplan-Meier estimate for 50% survival was 4.5 days. Mean peak viremia for nonvaccinated birds was 106.4 PFUs/ml (6100.2 PFUs/ml, standard error of the mean [SEM]). Virus was shed cloacally and orally. Four of the five vaccinated grouse died, but survival time was increased (50% survival59.5 days), with 1 grouse surviving to the end-point of the experiment (14 days) with no signs of illness. Mean peak viremia for the vaccinated birds was 102.3 PFUs/ml (6100.6 PFUs/ml, SEM). Two birds cleared the virus from their blood before death or euthanasia. These data emphasize the high susceptibility of greater sage-grouse to infection with WNV

West Nile Virus Quantification In Feces Of Experimentally Infected American And Fish Crows

To better understand the potential environmental health risk presented by West Nile virus (WNV)- contaminated feces, we quantified the amount of WNV present in the feces of experimentally infected American crows (Corvus brachyrhynchos) and fish crows (Corvus ossifragus). Peak fecal titers ranged from 103.5 to 108.8 plaque-forming units (PFU)/g for 10 American crows and from 102.3 to 106.4 PFU/g for 10 fish crows. The presence of infectious WNV in bird feces indicates a potential for direct transmission of WNV. Thus, handlers of sick or dead birds should take appropriate precautions to avoid exposure to fecal material

SEROLOGIC EVIDENCE OF WEST NILE VIRUS EXPOSURE IN NORTH AMERICAN MESOPREDATORS

Sera from 936 mammalian mesopredators (Virginia opossums, gray foxes, striped skunks, hooded skunks, raccoons, a bobcat, and a red fox) were collected during 2003 and 2004 in California, Arizona, Texas, Louisiana, Ohio, and Wyoming and screened for flavivirus-specific antibodies by an epitope-blocking enzyme-linked immunosobent assay (blocking ELISA). Serum samples positive for antibodies against flaviviruses were screened for West Nile virus (WNV)– specific antibodies by blocking ELISA and selectively confirmed with plaque-reduction neutralization tests. High prevalence rates were observed in raccoons (45.6%) and striped skunks (62.9%). The high WNV antibody prevalence noted in mesopredators, their peridomestic tendencies, and their overall pervasiveness make these species potentially useful sentinels for monitoring flaviviruses in defined areas

Experimental Infection of Fox Squirrels (\u3ci\u3eSciurus Niger\u3c/i\u3e) With West Nile Virus

Tree squirrels (Sciurus spp.) have exhibited high seroprevalence rates, suggesting that they are commonly exposed to West Nile virus (WNV). Many characteristics of WNV infections in tree squirrels, such as the durations and levels of viremia, remain unknown. To better understand WNV infections in fox squirrels (S. niger), we subcutaneously inoculated fourteen fox squirrels with WNV. Peak viremias ranged from 104.00 plaque-forming units (PFU)/mL of serum on day 2 post-infection (DPI) to 104.98 PFU/mL on 3 DPI, although viremias varied between individuals. Oral secretions of some fox squirrels were positive for WNV viral RNA, occasionally to moderate levels (103.2 PFU equivalent/swab). WNV PFU equivalents in organs were low or undetectable on 12 DPI; gross and histologic lesions were rare. The viremia profiles of fox squirrels indicate that they could serve as amplifying hosts in nature. In addition, viral RNA in the oral cavity and feces indicate that this species could contribute to alternative WNV transmission in suburban communities