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2011 West Nile Virus Activity

This map details mosquitoes, dead birds, chickens, and horses that have tested positive for West Nile virus. You can zoom in and out of the map and click on the placemarkers to get a detailed description of the date the positive activity was confirmed and the approximate location.

May contain: cutlery, spoon, chart, and plot

 For information regarding human cases, please click here.


Mosquito Samples: 7
nDate CollectedCityCross StreetsSpecies
18/17OakleyWest Cypress Road x Ohara Ave.Cx. tarsalis
28/29KnightsenHolland Tract x Old RiverCx. tarsalis
38/31BrentwoodSellers Ave. x Chestnut St.Cx. pipiens
49/8BrentwoodSellers Ave. x Chestnut St.Cx. pipiens
59/21ConcordMinert Rd. x San Simeon Dr.Cx. tarsalis
610/3ConcordBates Ave. x Mason Cir.Cx. pipiens
710/12BrentwoodSellers Ave. x Chestnut St.Cx. pipiens
Dead Birds: 43
nDate ReportedCityCross StreetsSpecies
16/29Walnut CreekTreat Blvd. x Bancroft Rd.American Crow
27/5PittsburgLoveridge Rd. x Buchanan Rd.Western Scrub Jay
37/25AntiochDeer Valley Rd. x Sand Creek Rd.American Crow
48/19ConcordOak Grove Rd. x Treat Blvd.American Crow
58/10Pleasant HillMonument Blvd. x Buskirk Ave.American Crow
68/10AlamoDanville Blvd. x Camille Ave.Western Scrub Jay
78/23ConcordTreat Blvd. x Oak Grove Rd.American Crow
88/29Walnut CreekWalnut Blvd. x Mountain View Blvd.Western Scrub Jay
98/31KnightsenDelta Rd. x Knightsen Ave.American Crow
109/2ConcordOak Grove Rd. x Monument Blvd.Western Scrub Jay
119/2BrentwoodLone Tree Way x Fairview Ave.American Crow
129/6Walnut CreekBancroft Rd. x Oak Grove Rd.American Crow
138/25OakleyW. Cypress Rd. x Empire Ave.Western Scrub Jay
149/7ConcordOak Grove Rd. x Treat Blvd.American Crow
159/8ConcordOak Grove Rd. x Minert Rd.American Crow
169/5BrentwoodHwy 4 Bypass x Balfour Rd.Western Scrub Jay
179/1ConcordOak Grove Rd. x Minert Rd.Western Scrub Jay
189/12Pleasant HillEllinwood Dr. x Contra Costa Blvd.American Crow
199/12LafayetteOld tunnel Rd. x Pleasant Hill Rd.American Crow
209/12ConcordDavid Ave. x Mohr Ln.Western Scrub Jay
219/14BrentwoodMain St. x Sycamore Ave.American Crow
229/14Pleasant HillGergory Ln. x Contra Costa Blvd.American Crow
239/18ConcordMinert Rd. x Oak Grove Rd.American Crow
249/19Walnut CreekWalnut Ave. x Oak Grove Rd.Western Scrub Jay
259/20ConcordHwy 4 x Hwy 242American Crow
269/22ConcordFarm Bureau Rd. x Concord Blvd.American Crow
279/22Pleasant HillContra Costa Blvd. x Taylor Blvd.American Crow
289/23ConcordCowell Rd. x Coventry Rd.Western Scrub Jay
299/19ConcordCowell Rd. x Treat Blvd.Western Scrub Jay
309/14Discovery BayStarboard Dr. x Willow Lake Rd.Western Scrub Jay
319/30Walnut CreekOak Grove Rd. x Mitchell Dr.Western Scrub Jay
3210/1ConcordWillow Pass Rd. x Grant St.American Crow
3310/4Pleasant HillBoyd Rd. x Contra Costa Blvd.American Crow
3410/4ConcordOlivera Rd. x Port Chicago HwyAmerican Crow
3510/5ConcordTreat Blvd. x Clayton Rd.American Crow
3610/6OakleyHwy 4 x Oakley Rd.American Crow
3710/7ConcordSan Jose Ave. x Clayton Rd.American Crow
3810/11ConcordClayton Rd. x Farm Bureau Rd.American Crow
3910/11Pleasant HillViking Dr. x Contra Costa Blvd.American Crow
4010/12OakleyW. Cypress Rd. x Empire Ave.American Crow
4110/14ConcordSan Simeon Dr. x Treat Blvd.American Crow
4210/14Pleasant HillBoyd Rd. x Patterson Blvd.American Crow
4310/14ConcordSan Simeon Dr. x Treat Blvd.American Crow


Sentinel Chicken Flocks: 0
#/10Date BleedArea

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


Horses: 0
nDate ReportedCityDead/Euthanized