CONCORD, CALIFORNIA – The Contra Costa Mosquito & Vector Control District is reporting a dead bird from Brentwood and mosquitoes from Discovery Bay have tested positive for West Nile virus. This is the second group of mosquitoes from Discovery Bay and the first dead bird of the year from Contra Costa County to test positive for the virus.
This virus activity serves as an important reminder that residents should wear repellent to reduce the risk of mosquito bites, especially as summer heat continues, prompting residents to delay outdoor activities until temperatures cool in the evening. The mosquitoes that can transmit West Nile virus are active at dawn and dusk.
According to the District’s Scientific Programs Manager Steve Schutz, Ph.D., “Although this is the second group of mosquitoes from Discovery Bay to test positive for West Nile virus, virus transmission can occur anywhere in the county so it’s very important to wear repellent if you’re going to be outdoors in the evening.”
The District also urges the public to report dead birds to the state hotline: 1-877-968-2473. Birds are often the first sign of disease transmission. Ravens, jays, crows, and magpies can be susceptible to the virus, and may die if infected.
Even if the birds are not tested, the reports alone yield crucial information to protect public health.
The District encourages residents to reduce their risk of contracting West Nile virus and other mosquito-borne diseases by:
- Dumping or draining standing water to prevent mosquitoes – most mosquitoes can’t start their lives without water.
- Defending yourself – use repellents containing DEET, Picaridin, or Oil of Lemon Eucalyptus.
- Avoiding the outdoors when mosquitoes are present, typically dawn and dusk
For a list of Contra Costa County’s 2018 West Nile virus activity and locations, visit the District’s website.
Mosquito Samples: 3
| n | Date Reported | City | Cross Streets | Species |
| 1 | 7/11/18 | Discovery Bay | Cherry Hills Drive x Hwy 4 | Culex pipiens |
| 2 | 7/16/18 | Agricultural Area East of Brentwood | Orwood Road x Levee Road | Culex tarsalis |
| 3 | 7/30/18 | Discovery Bay | Marina Rd x Willow Lake Rd | Culex pipiens |
Dead Birds: 1
| n | Date Reported | City | Cross Streets | Species |
| 1 | 7/29/18 | Brentwood | Sycamore Ave xGarin Pky | California Scrub-Jay |
Sentinel Chicken Flocks: 2
Note: Chickens do not die from West Nile virus. They develop antibodies to the virus which is detected in their blood.
| #/10 | Date Bleed | Area |
| 7 | 7/2/18 | Holland Tract |
| 3 | 7/16/18 | Martinez |
Horses: 0
| n | Date Reported | City | Dead/Euthanized |
Since 2005, 63 Contra Costa County residents 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. Visit the office between 8:00 a.m. and 4:30 p.m. to get FREE mosquitofish for ornamental ponds, horse troughs or neglected swimming pools.
