St. Louis County Department of Health officials are urging residents to take steps to eliminate breeding grounds after mosquitoes collected in 11 locations recently tested positive for West Nile Virus.

“There have been no reported human cases of WNV in St. Louis County this year, but positive mosquito tests remind us that preventative measures are important,” Dr. Michael Williams, director of the Di-vision of Communicable Disease Control Services and Emergency Preparedness, stated in a news release.

The mosquitoes that tested positive for West Nile Virus were trapped in Affton, Manchester, Frontenac, Chesterfield, unincorporated Fenton, Calverton Park, two separate locations in Sunset Hills, unincorporated Creve Coeur and Oakland.

“Even though serious WNV 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 using repellants,” Williams stated.

Here are steps residents can take to reduce the opportunities for mosquitoes to flourish:

• Standing water — don’t stand for it. Every two or three days, drain water from garbage cans, buckets, toys, flowerpots, wading pools, pet dishes, and other objects that can collect water. Change water in birdbaths at least once a week.

• Look for products containing the active ingredient methoprene or Bacicllus thur-ingiensis israelensis to place in birdbaths or ponds to prevent mosquitoes from de-veloping.

• Keep gutters clean and repair any tears in door and window screens.

• Wear long-sleeved shirts, long pants and light colors when outdoors and minimize exposure between dusk and dawn when mosquitoes are most active.

• Spray clothing with repellents containing DEET. Always follow manufacturer’s directions.

The health department routinely collects mosquito samples to help determine where to focus control efforts. To find out where the county’s vector control crew will be spraying, call (314) 615-4BUG for the nightly mosquito-spraying schedule.

For more information about mosquito prevention, contact the County Vector Control Office at (314) 727-3097.