First isolation of La Crosse virus from naturally infected Aedes albopictus

Le Crosse virus (LAC), a California serogroup bunyavirus, is the leading ca use of pediatric arboviral encephalitis in the United States and an emergin g disease in Tennessee, West Virginia, and North Carolina. Human cases of L AC encephalitis in Tennessee and North Carolina have increased above endemi c levels during 1997 to 1999 and may represent an expansion of a new southe astern endemic focus. This report describes the isolation of LAC virus from the exotic mosquito Aedes albopictus. The discovery of LAC virus in wild p opulations of Ae. albopictus, coupled with its expanding distribution in th e southeastern United States, suggests that this mosquito may become an imp ortant accessory vector, potentially increasing the number of human cases i n endemic foci or expanding the range of the disease.