SIOUX FALLS, S.D. — West Nile virus mosquito pools have been detected in two South Dakota counties, the state Department of Health confirmed Thursday, July 15.

The virus has been detected in mosquito pools in Brookings and Codington counties, state health officials said. They urged South Dakotans to take steps to protect themselves and their families against West Nile virus, which can cause fever, headaches, rash, swollen lymph nodes and muscle and joint aches.

“Given the rural nature of our state and increased outdoor activities during the summer, protecting yourself against mosquito bites remains an important factor against West Nile infection,” said Dr. Joshua Clayton, state epidemiologist for the Department of Health, in a news release. “Something as simple as using bug spray or limiting activities between dusk-to-dawn hours can reduce your infection risk significantly.”

Personal precautions against West Nile virus are most important for those at the highest risk for the virus, state health officials say. Those people include those over age 50, pregnant women, transplant patients, individuals with diabetes or high blood pressure and those with a history of alcohol abuse. People with severe or unusual headaches should see their physicians.

Prevent mosquito bites and reduce the risk of WNV with the following precautions:

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  • Apply mosquito repellents (DEET, picaridin, oil of lemon eucalyptus 2-undecanone, param-menthane-diol, or IR3535) to clothes and exposed skin. Limit exposure by wearing pants and long sleeves in the evening;
  • Limit time outdoors from dusk to midnight when mosquitoes are most active. The mosquito species Culex tarsalis are the primary carrier of West Nile virus in South Dakota;
  • Remove standing water that gives mosquitoes a place to breed. Regularly change water in bird baths, outside pet dishes, and drain water from other flowerpots and garden containers and stay away from areas near standing water;
  • Support local mosquito control efforts.

No human cases of West Nile virus have yet been found in South Dakota. Nationwide, 11 cases have been reported including in North Dakota, Iowa, Arkansas, Texas and Arizona as of July 13, according to the Department of Health. One West Nile fatality, in California, was reported last week.

Models current predict South Dakota will have 85 cases of West Nile virus cases this year, considered a moderate amount.

Since its first human WNV case in 2002, the state has reported 2,634 human cases, including 850 hospitalizations and 46 deaths. Every county has reported cases.

For more information on West Nile virus and prevention steps, visit the Department of Health's website, DOH.SD.GOV.