Montana health officials are encouraging the public to take steps to avoid mosquito bites and prevent infection with West Nile virus (WNV). The state’s first human case has been reported in Rosebud County and reflects an early start to the season. The adult case was hospitalized and is now recovering.

West Nile virus
Culex quinquefasciatus

To prevent infection, advice includes wearing insect repellent when outdoors, removing standing water from around the home and wearing pants and long-sleeved shirts when possible. It also serves as a reminder that horse owners should get their animals vaccinated and revaccinate annually.

Summer is a prime time for exposure to mosquitos in Montana.  Removing mosquito breeding areas and preventing mosquito bites are two ways to prevent being infected with West Nile virus.

“The best way to prevent West Nile virus is to take personal precautions to avoid mosquito bites,” said DPHHS Director Richard Opper. “We encourage everyone to protect themselves while enjoying the outdoors this summer.”

Public health officials offer the following advice to avoid being bitten and encourage all Montanans to remember the 4 D’s of West Nile virus prevention to reduce their chances of becoming ill.

Dusk / Dawn – Mosquitoes carrying West Nile virus usually bite at dusk and dawn.  Limit outdoor activity during those times and if you must be outside protect yourself from bites.
Dress – Wear long-sleeved shirts and pants to reduce the amount of exposed skin.

DEET – Cover exposed skin with a repellant containing the chemical DEET, which is most effective against mosquito bites.

Drain – Empty any containers holding standing water because they can be excellent breeding grounds for virus-carrying mosquitoes.

West Nile virus is transmitted to humans by infected mosquitos through bites. Three to 14 days after being bitten by a mosquito that carries West Nile virus, about 1 in 5 of those infected will develop a low grade fever, headache and muscle aches lasting for three to six days.  Generally, no treatment is needed. However, in less than 1percent of infected people, serious, life-threatening symptoms develop including 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 immediately. Luckily, most infected people don’t develop symptoms and never knew that they were bitten by an infected mosquito.

The number of West Nile virus human cases in Montana has been highly variable from year to year since it came to Montana in 2002.  Over 200 cases were reported in 2003 and 2007 and none in 2010.  In 2014, 5 cases were reported.  “Scientists have not been able to predict the number of West Nile virus cases, so it is important to protect yourself from mosquito bites and eliminate breeding sites around your home,” said Christine Mulgrew, DPHHS WNV Program Manager.  With over 90 percent of cases occurring in August and September, it is time to start actively preventing mosquito bites, she said.

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