West Nile Virus: Three New Human Cases Reported in Contra Costa County

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CONCORD, CALIFORNIA – The Contra Costa Mosquito & Vector Control District received reports of three more people testing positive for West Nile virus and is reporting another dead bird and mosquito sample as well.

“These people were most likely infected in August or September, with symptoms presenting themselves usually three to 14 days later. That, combined with doctor’s visits, a thorough investigation including travel history, testing and notification to the various agencies takes time and is why cases are announced at a later date,” said Steve Schutz, Ph.D., scientific program manager for the District. “Our District is notified by the local health department of locations where human infections may have occurred and we respond immediately, even before travel history is known, to conduct thorough surveillance and control, if needed, in those areas.”

The District works collaboratively with the health department due to the nature of vectors — animals or insects that transmit disease or cause discomfort to people. All questions concerning human cases should be directed to the state or local health department.

Other West Nile virus activity continues in Contra Costa County. The District reports today that another group of mosquitoes from an agricultural area east of Discovery Bay tested positive for West Nile virus as well as one dead bird from Alamo. All 2014 West Nile virus vector activity can be found on the District’s website.

According to the California West Nile Virus website, so far this year compared to the same time last year there are 488 human cases compared to 236 last year, 2275 dead birds compared to 1168 last year, 3139 mosquito samples compared to 2440 last year, and 382 chickens compared to 425 last year .

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, 52 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 five people, 23 groups of mosquitoes, 14 chickens and 43 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: 23

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
209/11/14BrentwoodOrwood TractCulex pipiens
219/16/14Discovery BayAgricultural AreaCulex pipiens
229/22/14Discovery BayByron Tract NWCulex tarsalis
2310/6/14Discovery BayByron Tract NWCulex pipiens

Dead Birds: 43

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
369/8/14San RamonBroadmoor Dr. x Pine Valley Rd.American Crow
379/8/14OrindaAltamount Dr. x Moraga Wy.Stellar’s Jay
389/12/14DanvilleVerona Ave. x Love Ln.American Crow
399/15/14San RamonAscot Dr. x Broadmoor Dr.American Crow
409/21/14DanvilleCamino Ramon x El Capitan Dr.American Crow
419/24/14Discovery BayClubhouse Dr. x Edgeview Dr.American Crow
429/29/14MartinezGlacier Dr. x Olympic Dr.Western Scrub Jay
4310/8/14AlamoRoyal Oaks Dr. x Peake Pl.American Crow

Sentinel Chicken Flocks: 3 (14 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
1/107/14/14Oakley
1/107/28/14Holland Tract
1/108/11/14Holland Tract
1/108/11/14Oakley
3/108/11/14Walnut Creek
1/108/25/14Walnut Creek
1/109/22/14Holland Tract

Horses: 0

nDate ReportedCityDead/Euthanized