Serologic Evidence of West Nile Virus Infection in Free-Ranging Mammals, Slidell, Louisiana, 2002

Abstract

After an outbreak of West Nile virus (WNV) infections in Slidell, Louisiana, in 2002, we detected neutralizing antibodies to WNV in 13 of 120 mammals, representing five of six species sampled. Seroprevalence was measured in opossum, Didelphis virginiana (75%, n = 8), raccoons, Procyon lotor (60%, n = 5), black rats, Rattus rattus (6%, n = 36), hispid cotton rats, Sigmodon hispidus (4%, n = 24), and eastern gray squirrels, Sciurus carolinensis (2%, n = 43).

Land Use and West Nile Virus Seroprevalence in Wild Mammals

“…Several mammal species have been found to be naturally exposed to WNV, and it has been suggested that wild mammals could be used as indicators of transmission (2)(3)(4). WNV seroprevalence in wild mammals will be a useful indicator of WNV activity only if it differs between sites, if it refl ects within-season transmission, and if other key confounding factors are accounted for.…”

“…First, we predicted that WNV seroprevalence would differ signifi cantly among species because of differences in mosquito preferences, mammal behavior and survival, and other factors (2,3). Second, we predicted that seroprevalence would be higher for adults than for juveniles because adults have been exposed to WNV for at least 1 additional year.…”

Experimental Infection of Raccoons (Procyon lotor) with West Nile Virus

“…35 The relatively high WNV seroprevalence among raccoons suggests that they may be frequently fed upon by some mosquito species. [2][3][4][5][7][8][9] In addition, significant fecal shedding was noted in some raccoons, which may have transmission implications among wildlife by the behavioral ecology of this mesopredator. Thus, although raccoons are well documented to be commonly exposed to WNV in nature, 3,5 their role in WNV transmission, if any, may be more likely to be associated with fecal contamination of the environment rather than involvement in mosquito-host transmission cycles.…”

“…[1][2][3][4][5][6][7][8][9] Despite the apparent lack of mammalian involvement in WNV cycles and the general contention that they serve as dead-end hosts, 10 researchers have established that various mammals serve as potential competent reservoir hosts. For example, viremia titers of ≥ 10 5.0 plaque forming units (PFU)/mL serum were observed in some experimentally infected golden hamsters ( Mesocricetus auratus ).…”

Detection of Antibodies against Japanese Encephalitis Virus in Raccoons, Raccoon Dogs and Wild Boars in Japan

“…These animals might therefore affect the lifecycle of infectious diseases in Japan. In raccoons in the North America, it has been reported that more than 75.0% in Los Angeles [1] and 19.2% (15 out of 78) in southern Wisconsin [2] have virus-neutralizing (VN) antibodies against West Nile virus (WNV). In Singapore, VN antibodies against JEV were detected in all 28 wild boars tested from June to July 1999 [13].…”