LA CROSSE VIRUS INFECTIONS IN TENNESSEE: AN EMERGING INFECTION

Abstract
La Crosse virus is the most common arboviral cause of pediatric encephalitis in the United States. In 1997, a new focus of La Crosse virus activity was identified in eastern Tennessee, a state in the southeastern United States. Approximately 10 cases per year of La Crosse encephalitis have been reported from that region since 1997. A low prevalence of antibodies to La Crosse virus in the general population suggests that the virus has been newly introduced to the area, rather than simply newly recognized. A case-control study identified increased time outdoors, living near trees with holes, and exposure to Aedes albopictus as risk factors for developing La Crosse encephalitis. La Crosse virus, which is generally believed to be transmitted by Aedes triseriatus (the treehole mosquito) was isolated for the first time in naturally infected Ae. albopictus (the Asian tiger mosquito) in Tennessee. It will be important to study whether this new mosquito vector may be contributing to the spread of this virus. The emergence of a number of arboviruses in the United States reinforces the need for an adequately funded, adaptable public health infrastructure to respond to continually changing infectious public health threats.

Key words
La Crosse, encephalitis, California, arbovirus

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