CONCORD, CALIFORNIA – The Contra Costa Mosquito & Vector Control District (District) reports a group of mosquitoes has tested positive for West Nile virus (WNV) in Contra Costa County. The mosquitoes were collected from traps in an agricultural area east of Byron. This is the first group of mosquitoes to test positive for WNV so far this year in Contra Costa County.
Certain types of birds may carry WNV. When a mosquito bites an infected bird, the mosquito can become infected and transmit WNV to another bird or a person through a mosquito bite.
The discovery of infected mosquitoes at the start of the Fourth of July weekend serves as an important reminder for Contra Costa County residents to wear insect repellent to prevent mosquito bites while out enjoying the holiday festivities.
“The hot weather that often accompanies the 4th of July weekend also increases the risk of West Nile virus. Mosquitoes can develop from egg to adult more quickly in warmer weather and West Nile virus replicates faster within mosquitoes when temperatures stay above 54 degrees overnight. So, it is very important that residents wear insect repellent this weekend as hot weather significantly increases the chances of disease transmission to people,” said the District Scientific Program Manager Steve Schutz, Ph.D.
Contra Costa County residents can reduce the risk of WNV by taking these necessary steps to prevent mosquitoes:
- Dump or drain standing water. Mosquitoes develop from egg to adult in water.
- Defend yourself—use repellents containing DEET, Picaridin, or Oil of Lemon Eucalyptus.
- Keep swimming pools chlorinated and filtered because just one neglected pool can produce up to 1 million mosquitoes and affect people several miles away.
- Avoid the outdoors when mosquitoes are present, typically dawn and dusk.
Contra Costa County residents can also report dead birds by phone at (877) WNV-BIRD (968-2473) or online.
Since 2005, 73 people in Contra Costa County have been diagnosed with West Nile virus. In 2006, two people died from the disease. For current human case information, please contact Contra Costa Health Services at 888-959-9911.
Contra Costa Mosquito & Vector Control District, an independent special district and public health agency, is located at 155 Mason Circle in Concord. Contact the District to report mosquito problems online or at (925) 685-9301.