The St. Louis County Department of Public Health (DPH) has recorded its first confirmed human case of West Nile virus this year. Cases have also been reported in neighboring jurisdictions, and the St. Louis County DPH has been notified of three blood donors whose blood has tested positive for WNV.
WNV is the leading cause of mosquito-borne disease in the continental United States and is most commonly transmitted to people by the bite of an infected mosquito. The Missouri Department of Health and Senior Services data shows one reported human case of West Nile in St. Charles County and two reported human cases in St. Louis city.
Most people infected with WNV do not feel sick, although about 1 in 5 people who are infected develop a fever or other symptoms including:
- Headache
- Body aches
- Joint pain
- Vomiting
- Diarrhea
- Rash
About 1 out of 150 infected people develop a serious, sometimes fatal, illness. There is no vaccine to prevent or medications to treat WNV in people.
“It is important for everyone to take steps to reduce the chance of contracting West Nile virus,” said Dr. Kanika Cunningham, director of the department, in a press release. “Even though serious West Nile virus cases in humans are rare, it is important to minimize our exposure. We can do this by eliminating opportunities for mosquitoes to breed and multiply, and by taking steps to prevent mosquito bites.”
Here are steps residents can take to prevent WNV:
- When outdoors, wear long-sleeved shirts, long pants and light-colored, loose-fitting clothing.
- Apply insect repellents registered by the Environmental Protection Agency that contain one of the following active ingredients: DEET, picaridin, oil of lemon eucalyptus, para-menthane-diol or IR3535. Always follow the directions on the label. Do not use products that contain oil of lemon eucalyptus or para-menthane-diol on children younger than 3 years of age, and never apply insect repellants of any kind to children under 2 months of age.
- At least once a week, eliminate any sources of standing water around your home by draining garbage cans, buckets, toys, flowerpots, wading pools, pet dishes, and other objects. Turn them over to prevent them from refilling with water.
- Fill any holes or depressions in the yard with sand or dirt.
- Drill holes in the bottom of tire swings to allow water to drain.
- Change the water in birdbaths at least once a week and keep all gutters cleaned out.
- Treat birdbaths, decorative ponds, and other water sources that cannot be drained with products containing the active ingredient Bacillus thuringiensis israelensis, or Bti, a naturally occurring bacterium. Bti contains spores that produce toxins that specifically target and affect the larvae of the mosquito, blackfly and fungus gnat. It is non-toxic to humans and other animals and is approved for use in organic farming.
- Ensure that drainage pipes are properly sloped. Flexible drainage pipe is commonly used to drain water from downspouts. However, if it is not properly installed, the pipe can hold water and breed mosquitoes.
- Repair tears in door and window screens to prevent mosquitoes from entering a home.
Additionally, for unincorporated Saint Louis County and municipalities that contract with DPH, the program monitors and treats standing water in public areas as part of its preventative larviciding program and sprays for adult mosquitoes in areas with WNV- positive mosquitoes or high numbers of the types of mosquitoes that transmit WNV. To find out where the county will be spraying, call 314-615-4-BUG (314-615-4284) for the nightly mosquito-spraying schedule.
