July 16, 2025:
The South Dakota Department of Health confirmed the first human West Nile virus (WNV) case of the 2025 season in a resident of Brookings County. South Dakota has reported more than 2,864 human cases and 54 deaths since WNV was first reported in 2002.
“West Nile virus is an infection most commonly spread through mosquito bites,” said Dr. Joshua Clayton, state epidemiologist. “The rate of severe infection that includes swelling of the brain and spinal cord with symptoms of stiff neck, confusion, and muscle weakness is highest in South Dakota and other Midwest states. Raising awareness of human cases can ensure residents and visitors alike take action to reduce their risk.”
Individuals and families can reduce their risk by taking the following actions:
- 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. Culex tarsalis are the primary carrier of WNV in South Dakota;
- Remove standing water that gives mosquitoes a place to breed. Regularly change the water in birdbaths, outside pet dishes, and drain water from other flowerpots and garden containers and stay away from areas near standing water; and
- Support local mosquito control efforts.
These precautions are especially important for people at high risk for WNV, including individuals over 50, pregnant women, organ transplant patients, individuals with cancer, diabetes, high blood pressure or kidney disease, and those with a history of alcohol abuse. People with severe or unusual headaches should see their physicians.
For more information about West Nile virus, visit the South Dakota DOH website. The department’s surveillance page also provides updated data, including which counties have reported human cases.
June 26, 2025:
The South Dakota Department of Health has confirmed the detection of the first West Nile virus mosquito pools in the state this season. They were found in Minnehaha County.
Officials urge individuals across the state to take simple steps to protect themselves and their families against WNV, which can cause symptoms such as fever, headaches, rash, swollen lymph nodes and muscle and joint aches.
Prevent mosquito bites and reduce the risk of WNV by taking the following precautions:
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Apply mosquito repellents (DEET, picaridin, oil of lemon eucalyptus 2-undecanone, para-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. Culex tarsalis is the primary carrier of WNV in South Dakota.
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Remove standing water that provides mosquitoes with a breeding ground. Regularly change the water in birdbaths, outside pet dishes, and drain water from other flowerpots and garden containers. Also, avoid areas near standing water.
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Support local mosquito control efforts.
State Epidemiologist Dr. Josh Clayton says using bug spray or limiting activities between dusk-to-dawn hours can significantly reduce your risk of infection.
Personal precautions are especially important for those at high risk for severe illness from WNV – people over 60 years of age, pregnant women, transplant patients, individuals with cancer, diabetes, hypertension and kidney disease. Individuals experiencing fever with headache, muscle aches or rash should consult their physician. South Dakota has reported more than 2,864 human cases and 54 deaths since WNV was first reported in 2002. Every county has reported cases.
For more information on WNV, visit the DOH website.
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