Surveillance for West Nile Virus at the International Crane Foundation 2000-2004

Between 2000 and 2004, serum samples collected annually from captive cranes at the International Crane Foundation (ICF) were analyzed for the presence of West Nile virus (WNV) antibodies using a plaque reduction neutralization test. Eighteen individual cranes representing 8 species were identified with positive titers (geometric mean = 188, range 40 – 1280, n = 29). Whooping cranes (Grus americana) represented the largest proportion of seropositive individuals (33%). Flock seroprevalence increased rapidly in 2003 and 2004 to a peak of 10%, representing a four-fold increase following index cases in 2000. None of the seropositive cranes, however, showed clinical signs consistent with WNV-related disease during the study. The results suggest that exposure of ICF captive cranes to WNV is relatively common and re-affirmed the decision to implement a limited vaccination plan for hatch year whooping cranes believed to be at risk of disease from WNV. ProcEEDINGS of thE North AmErIcAN crANE WorkShoP 10:111–114