An outbreak of West Nile virus in a New York City captive wildlife population.

Abstract

Abstract. An outbreak of West Nile virus (WNV) in and around New York City during the late summer of 1999 was the cause of extensive mortality among free-ranging birds. Within the Bronx Zoo/Wildlife Conservation Park, viral activity was also observed and produced some morbidity and mortality among specimens in the zoo's bird collection and probably caused morbidity in at least one specimen from the zoo's mammal collection. To determine the extent of the outbreak and attempt to ascertain the temporal appearance of virus within the park, a serologic survey of birds and mammals was performed. The survey showed that 34% of tested birds (125 of 368; 124 species) were positive for antibody to WNV. The virus caused a disease to infection ratio of 22% (27 of 125) among birds with a 70% (19 of 27) case fatality rate. In contrast, only 8% of the mammals (9 of 117; 35 species) possessed antibody to WNV and there was no virus-associated mortality. Testing of banked and fresh sera obtained from both birds and mammals revealed that there was no evidence of WNV circulation before the 1999 outbreak and that birds introduced into the park were not the source of the New York outbreak. West Nile virus RNA was detected in tissues from one bird that died in February 2000, long after the end of the mosquito transmission season. The potential importance of zoologic parks as possible sentinels for emerging diseases is discussed.

Risk Factors Associated With West Nile Virus Mortality in American Crow Populations in Southern Quebec

“…Two studies have shown that sensitivity to WNV increases with age: one on geese with an Israeli strain (McLean et al, 2002) and another on chickens with an Egyptian strain (Malkinson et al, 2001). Although both the Egyptian and Israeli strains closely resemble the NY99 strain present in North American, neither geese nor chickens are passerines (Ludwig et al, 2002;Meulen et al, 2005), which limits the comparability of these results to our findings. In 2002, during a WNV epidemic in an Ontario owl population, HY owls were more resistant to WNV than were adult owls (Gangz et al, 2004).…”

“…This lower BCI could have been caused by dehydration or poor body condition after WNV infection. The high sensitivity of American Crows to WNV, the high rate of mortality following WNV infection, and the swiftness of death-approximately seven days post-infection (Ludwig et al, 2002;Komar et al, 2003)-could cause major dehydration or a lowered BCI in the infected American Crow.…”

“…In 1999, West Nile virus (WNV) made its first appearance in North America in New York State (Marfin et al, 2001;Ludwig et al, 2002;McLean et al, 2002). It struck immunologically naïve populations, resulting in widespread mortality in birds and mammals (Kulasekera et al, 2001).…”

West Nile Virus Infection in Nonhuman Primate Breeding Colony, Concurrent with Human Epidemic, Southern Louisiana

“…Serosurveys among equines living in WNV-endemic areas, as well as results of WNV experimental infections of horses, indicate that most equine infections are inapparent or result in only mild clinical illness (4-7). Most reported WNV-associated bird deaths in the United States have been in crows and blue jays (2,8), two species with a relatively high case-fatality rate; however, many other bird species are naturally infected with the virus and have few or no deaths (8)(9)(10)(11). Because the current WNV surveillance systems in the United States are largely disease-and death-based (cases of human meningoencephalitis, equine encephalitis, dead birds), the actual prevalence of WNV infection among humans and other susceptible vertebrate hosts and the intensity of virus transmission are underestimated.…”

A Survey for West Nile Virus in Bats from Illinois

“…Mosquitoes are the primary vectors for WNV, and wild birds are the principal hosts (Hubalek and Halouzka, 1999;Campbell et al, 2002;McLean et al, 2002). Evidence of WNV infections in a variety of vertebrates (Steele et al, 2000;Komar et al, 2001;Ludwig et al, 2002;Lichtensteiger et al, 2003;Steinman et al, 2003;Heinz-Taheny et al, 2004) suggests that WNV is widespread in wildlife, and other vertebrate hosts might serve as an overwintering and maintenance reservoir for WNV.…”