West Nile virus infection in nonhuman primate breeding colony, concurrent with human epidemic, southern Louisiana.

Marion S Ratterree,Frank B Cogswell,Amelia P.A Travassos Da Rosa,Robert B Tesh,Robert E Shope,Kathrine M Phillippi,Kevin Caillouet,Shelle Schwanberger,Rudolf P Bohm

doi:10.3201/eid0911.030226

Marion S Ratterree, Frank B Cogswell + Show 7 more

Open Access

https://doi.org/10.3201/eid0911.030226

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Abstract

During the summer of 2002, an epidemic of West Nile meningoencephalitis occurred in southern Louisiana. Following the outbreak, blood samples were collected from 1,692 captive rhesus monkeys (Macaca mulatta), pigtail macaques (M. nemestrina), and baboons (Papio spp.) that were permanently housed outdoors at a nonhuman primate breeding facility in St. Tammany Parish, Louisiana. The serum samples were examined for antibodies to West Nile virus (WNV). Overall, 36% of the captive nonhuman primates had WNV antibodies; comparison of these samples with banked serum samples from previous blood collections indicated that the animals were infected subclinically from February to August 2002. WNV activity was demonstrated in surveillance at the nonhuman primate-breeding colony and in the neighboring community during this same period. The high infection rate in this captive nonhuman primate population illustrates the intensity of WNV transmission that can occur silently in nature among other susceptible vertebrates during epidemic periods.

Highlights

During the summer of 2002, an epidemic of West Nile meningoencephalitis occurred in southern Louisiana
On the basis of retrospective serosurveys conducted in New York City in 1999 and 2000, symptomatic illness develops in approximately 20% of persons infected with West Nile virus (WNV) and approximately 1 in 150 human infections results in meningoencephalitis, the most commonly reported form of WNV-associated illness [1,3]
All serum samples from these animals were screened by HI test against DENV-1, DENV-2, yellow fever (YFV), SLEV, and WNV antigens; a subset of the WNV antibody positives were tested by complement fixation (CF) and plaque reduction neutralization test (PRNT)

Summary

Introduction

During the summer of 2002, an epidemic of West Nile meningoencephalitis occurred in southern Louisiana. Despite the increasing number of reported West Nile cases and the wide vertebrate host range of this emerging flavivirus, surprisingly little information is available on the true prevalence of WNV infection among humans and animals living within newly epidemic regions in North America This paucity of information is partly due to the method in which WNV infections are recorded: only recognized cases of clinical illness or death are usually reported. The availability of sequential serum samples from these animals during a period of known epidemic WNV activity prompted us to examine some of the animals for serologic evidence of recent WNV infection The results of these studies are reported here and indicate that approximately 36% of the nonhuman primates tested from the breeding colony were naturally infected with WNV during the 2002 transmission season

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