Montana Confirms First Human West Nile Virus Case

Ruzanna Harutyunyan's picture

The Department of Public Health and Human Services (DPHHS) confirmed today the state’s first human case of West Nile virus for 2008 identified in a Richland County adult female.

According to health officials, the individual is thought to have acquired the infection in eastern Montana.

“The best way to prevent West Nile virus is to prevent mosquito bites,” said DPHHS communicable disease surveillance specialist Elton Mosher. “The more time you spend outdoors the more chance you have of being bitten by an infected mosquito. We encourage everyone to take precautions against West Nile while recreating outside this summer and as we move into early fall. Last year, we were still registering human cases into October.”

Human cases of West Nile are typically preceded by reports of positive tests in mosquito pools and horses. This year in Montana, there have been two reported cases of West Nile in horses in Lake County and mosquito pools in Cascade and Sheridan counties have also tested positive.

In 2007, there were 202 West Nile virus cases and five deaths reported in Montana. Yellowstone, Phillips and Roosevelt counties reported the most cases last year. Yellowstone registered 27 and both Phillips and Roosevelt reported 16. There were also 36 cases in horses.

To reduce the risk of being bitten by mosquitoes that may carry West Nile virus, the state health department recommends the following the tips from the 4 Ds West Nile prevention campaign. The 4 Ds include:

* DUSK/DAWN: Mosquitoes are most active during this time. If possible, stay indoors during the early morning and evening hours.


* DRESS: If you must be outdoors when mosquitoes are most active, dress in long sleeves and pants.

* DEET: Before going outdoors, remember to apply an insect repellent containing DEET (N, N-diethyl-m-toluamide). DEET is recommended by the Centers for Disease Control and Prevention (CDC) and is the most effective and best studied insect repellent available. Use a repellent containing 25 percent to 35 percent DEET when it is necessary to be outdoors. Children ages 2-12 should use repellent with 10 percent DEET or less. Products containing picaridin and permethrin have also been found to be effective in repelling mosquitoes, as has oil of lemon eucalyptus.

* DRAIN: To keep the mosquito population at bay around your home, drain standing water in old tires, barrels, buckets, cans, clogged rain gutters, and other items that collect water. Change water in pet bowls, flowerpots, and birdbaths at least twice a week.

Many people who become infected with West Nile 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 1 out of 150, may become severely infected with West Nile encephalitis or West Nile meningitis. It’s common for people over 50 to experience more severe symptoms than someone under that age.

Symptoms of this disease may include headache, rash, high fever, stiff neck, mental confusion, muscle weakness, tremors, convulsions, coma and paralysis. Individuals who develop any of these symptoms should see their health-care provider.

Montana's first confirmed case of West Nile virus involved a horse in Shepherd in late August 2002. That season, a total of one human and 134 horses were diagnosed with the disease. There were no human fatalities, but 38 horses either died or were euthanized.

In 2003, 226 human cases of West Nile were reported in Montana, including four deaths. In 2004, six cases were reported. In 2005, 26 cases were reported and in 2006, 34 cases were reported. No deaths were reported in 2004, 2005 or 2006.