(HealthDay) -- With 241 cases of West Nile virus and four related deaths reported so far this year, the United States is experiencing the biggest spike in the mosquito-borne illness since 2004, health officials report.
Eighty percent of these infections have occurred in three states -- Texas, Mississippi and Oklahoma -- which have seen earlier activity than usual. Overall, 42 states had detected West Nile virus infections in people, birds or mosquitoes as of July 31, the U.S. Centers for Disease Control and Prevention said Wednesday.
"It is not clear why we are seeing more activity than in recent years," Dr. Marc Fischer, medical epidemiologist with agency's Arboviral Diseases Branch, said in a CDC news release. "Regardless of the reasons for the increase, people should be aware of the West Nile virus activity in their area and take action to protect themselves and their family."
Typically, the greatest risk for infection with West Nile virus occurs from June through September, with cases peaking in mid-August. But changes in the weather, the number of infected mosquitoes and human behavior can all influence when and where outbreaks of the virus occur, the CDC noted.
The best way to protect yourself from West Nile virus is to avoid getting bitten by mosquitoes. CDC officials recommend the following protective measures:
- Use insect repellents when outside.
- Wear long sleeves and pants at dawn and dusk.
- Install or repair window and door screens.
- Use air conditioning whenever possible.
- Do not leave standing water outside in open containers, such as flowerpots, buckets and kiddie pools.
Although most people with mild cases of West Nile virus will recover on their own, the CDC recommends that anyone who develops symptoms of the illness should see their doctor right away.
Explore further: Mosquito sample with West Nile virus found in Oakley, Calif.
The U.S. National Institutes of Health provides more information on West Nile virus.