First West Nile virus case confirmed in Montana

The Montana Department of Public Health and Human Services recently confirmed the first human case of West Nile virus in Montana for 2009. The case was identified in a Lake County adult. According to health officials, the individual most likely acquired the infection in Lake County after receiving numerous mosquito bites.

In 2008, there were a total of five West Nile virus cases reported in Montana with no deaths. In 2007, there were 202 West Nile virus cases and five deaths. DPHHS bureau chief Jim Murphy attributes the difference in reported cases from 2007 to 2008 to weather and mosquito breeding patterns.

"The numbers can vary drastically," he said. "Weather conditions such as moisture and summer temperatures affect the breeding and numbers of mosquitoes. There has always been an up and down pattern to West Nile virus infections in humans since it was first identified in Montana in 2002."

Many people who become infected with West Nile virus experience no symptoms. Some individuals may develop a mild illness, called West Nile fever, which may last for three to six days. Generally, no treatment is needed. Other individuals, fewer than one out of 150, may become severely infected and develop symptoms of encephalitis or meningitis. There is no vaccine available for humans.

Preventing mosquito bites is the best way to avoid West Nile virus infection. The more time a person spends outdoors, the higher the chance of being bitten by an infected mosquito. DPHHS recommends that everyone take precautions against mosquito bites when outside this summer, including covering up, staying indoors at dusk and dawn, and using DEET insect repellent.

For more information about West Nile protection and detection efforts, contact the Communicable Disease Epidemiology Section at 406-444-0273 or visit online at http://cdepi.hhs.mt.gov.