Home Contra Costa County Risk of West Nile Virus Continues Despite the Unofficial End of Summer

Risk of West Nile Virus Continues Despite the Unofficial End of Summer

by ECT

Contra Costa Mosquito and Vector Control District

CONCORD, CALIFORNIA – – The Contra Costa Mosquito & Vector Control District reported Friday that four more birds have tested positive for West Nile virus, proving the risk of infection has not waned in spite of the unofficial end of summer. The birds that tested positive for the virus came from Brentwood (2), Walnut Creek (1), and Oakley (1). All 2014 West Nile virus activity can be found on the District’s website.

As West Nile virus is a disease that starts in birds, dead bird reports are a critical tool in the District’s Integrated Vector Management program because the location of each report becomes a target for scrutiny by District inspectors, technicians and laboratory staff. Without these reports, the District would be at a serious disadvantage.

“Without this information, we would most likely have to wait for mosquitoes or people to test positive for infection and that delay would put all Contra Costa County residents at an increased risk of disease,” said the District’s Scientific Programs Manager Steve Schutz, Ph.D.

The District urges residents to report all dead birds to the California Dead Bird Hotline  online or by calling 1-877-WNV-BIRD (1-877-968-2473). While each bird may not be a candidate for testing, every dead bird report is essential.

According to the California West Nile Virus website, at this same time last year there were 101 human cases compared to 181 this year, 987 dead birds compared to 1793 this year, and 1854 mosquito samples compared to 2485 this year. In fact, state health officials reported this week that the number of infected mosquitoes statewide is at an all time high, and so prevention is key. Infected mosquitoes can infect people with the virus in just a single bite.

Residents are urged to help reduce their risk of contracting mosquito-borne diseases by following these guidelines:

  • Dump or drain standing water. Mosquitoes can’t begin their lives without water.
  • Defend yourself against mosquitoes by using repellents containing DEET, Picaridin, or Oil of Lemon Eucalyptus.
  • Avoid being outdoors when mosquitoes are present, typically dawn and dusk.
  • Report neglected swimming pools by calling 925-771-6195 or visiting www.ContraCostaMosquito.com.  Anonymous calls accepted. Just one neglected pool can produce more than 1 million mosquitoes and affect people up to five miles away.
  • Report dead birds to the state hotline: 1-877-968-2473. All reports are crucial, even if the bird does not meet criteria for testing.

Since 2005, 48 people in Contra Costa County have been diagnosed with West Nile virus. In 2006, two people died from the disease. Recent studies have shown that the majority of cases are not diagnosed and are grossly underreported. For 2014, a total of 19 groups of mosquitoes, 13 chickens and 35 dead birds have tested positive for the virus.

Visit the District’s website or click on these links for current West Nile virus activity  or to receive automatic emails for when the District fogs for adult mosquitoes.

Contra Costa Mosquito & Vector Control District, an independent special district and public health agency, is located at 155 Mason Circle in Concord. Call the District to report mosquito problems at (925) 771-6195 or visit their office between 8:00 a.m. and 4:30 p.m. to get FREE mosquitofish for ornamental ponds, horse troughs or neglected swimming pools.


Mosquito Samples: 19

nDate ReportedCityCross StreetsSpecies
16/23/14KnightsenHolland Tract AreaCulex tarsalis
27/7/14Discovery BayCherry Hills DriveCulex pipiens
37/7/14MartinezI-680 x Waterfront RoadCulex tarsalis
47/14/14Discovery BayCherry Hills Drive x Marina RoadCulex pipiens
57/16/14Discovery BayBixler road x Balfour RoadCulex pipiens
67/17/14Discovery BayCherry Hills Drive x Wayfarer DriveCulex tarsalis
77/23/14Discovery BayByron Tract LeveeCulex tarsalis
88/6/14Discovery BayPoint of Timber Road x Bixler RoadCulex pipiens
98/12/14Discovery BayHighway 4 x Western Farms Ranch RoadCulex pipiens
108/13/14ConcordDavid Avenue x Cayce CourtCulex tarsalis
118/19/14Discovery BayByron Tract SECulex pipiens
128/19/14Discovery BayByron Tract NWCulex pipiens
138/19/14Discovery BayByron Tract NWCulex tarsalis
148/19/14Discovery BayByron Tract NWCulex tarsalis
158/20/14Discovery BayBixler Road x Point of Timber RoadCulex pipiens
168/18/14Discovery BayCherry Hills DriveCulex pipiens
178/25/14Discovery BayByron Tract NWCulex pipiens
188/26/14Discovery BayBixler Rd. x Point of Timber Rd.Culex pipiens
198/27/14Discovery BayWillow Lake Rd. x Beaver Ln.Culex pipiens

Dead Birds: 35

nDate ReportedCityCross StreetsSpecies
14/23/14AlamoDanville Blvd. x Camille Ave.American Crow
25/18/14Pleasant HillMonument Blvd. x Mohr Ln.American Crow
36/9/14San RamonNorris Canyon Rd. x Bollinger Canyon Rd.American Crow
4614/14OakleyEmpire Ave. x Main St.American Crow
56/17/14OakleyEmpire Ave. x Hemlock Dr.American Crow
66/17/14OakleyEmpire Ave. x Hemlock Dr.American Crow
76/20/14BrentwoodLone Tree Wy x O’Hara Ave.American Crow
86/25/14AntiochHillcrest Ave. x Sunset. Dr.American Crow
96/26/14San RamonBollinger Canyon Rd. x Norris Canyon Rd.American Crow
107/2/14Bethel IslandBethel Island Rd. x Gateway Rd.American Crow
117/9/14Walnut CreekArroyo Wy. x N. BroadwayAmerican Crow
127/10/14OakleyKay Ave. x O’Hara Ave.Western Scrub Jay
137/13/14AntiochCamby Rd. x G St.Western Scrub Jay
147/14/14BrentwoodFoothill Dr. x Balfour Rd.American Crow
157/16/14DanvilleHartford Rd. x Danville Blvd.American Crow
167/17/14AntiochHargrove St. x E. 18th St.American Crow
177/17/14BrentwoodMinnesota Ave. x Windmeadows Dr.Western Scrub Jay
187/21/14AntiochJudsonville Dr. x Hansen Dr.Western Scrub Jay
197/23/14ConcordBancroft Rd. x Hookston Rd.Western Scrub Jay
207/29/14PinoleMann Drive X Appian WayWestern Scrub Jay
218/6/14ConcordRyan Road x Wilmore AvenueAmerican Crow
228/6/14AlamoStone Valley Road x Roundhill RoadAmerican Crow
238/7/14DanvilleMontcrest Place x Love LaneWestern Scrub Jay
248/7/14Discovery BayCherry Hills Dr. x Wayfarer Dr.American Crow
258/10/14ConcordDavid Ave. x Getoun Dr.American Crow
268/11/14BrentwoodBurghley Ln. x Centennial Dr.American Crow
278/20/14ConcordTreat Blvd. x San Simeon Dr.American Crow
288/21/14Walnut CreekOak Rd. x Jones Rd.American Crow
298/21/14ConcordWhitman Rd. x W Gilardy Dr.American Crow
308/27/14Walnut CreekBancroft Rd. x Treat Blvd.American Crow
318/28/14DanvilleHarlan Dr. x St. Helena Dr.American Crow
329/2/14Walnut CreekWalnut Ave. x Warwick Dr.Western Scrub Jay
339/2/14OakleyEmpire Ave. x Truman Ln.American Crow
349/2/14BrentwoodForest View Common x Central Blvd.American Crow
359/4/14BrentwoodPayne Ave. x Walnut Blvd.Western Scrub Jay

Sentinel Chicken Flocks: 3 (13 chickens)

Note: Chickens do not die from West Nile virus. They develop antibodies to the virus which is detected in their blood.

# of Chickens out of 10 (10 per Flock)Date BledArea
1/106/16/14Holland Tract
3/106/30/14Holland Tract
1/107/14/14Holland Tract
1/107/28/14Holland Tract
1/108/11/14Holland Tract
3/108/11/14Walnut Creek
1/108/25/14Walnut Creek

Horses: 0

nDate ReportedCityDead/Euthanized

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