Mosquitoes in Jefferson County have tested positive for West Nile virus.

According to a press release from the Jefferson County Health Department, adult mosquitoes collected from an unincorporated part of De Soto were the first in Jefferson County to test positive in the county this season.

Earlier this week, St. Louis County public health officials announced mosquitoes carrying West Nile Virus were discovered in the county.

Tips from St. Louis County to reduce the opportunities for mosquitoes to breed and multiply

At least once a week, eliminate the sources of standing water around a 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 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 and ponds with products containing the active ingredient methoprene or Bti (Bacillus thuringiensis israelensis) to prevent mosquitoes from developing.

Ensure that drainage pipes are properly sloped. Flexible drainage pipe is commonly used to drain water from downspouts, but if not properly installed, they can hold water and breed mosquitoes.