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


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

n Date Reported City Cross Streets Species
1 6/23/14 Knightsen Holland Tract Area Culex tarsalis
2 7/7/14 Discovery Bay Cherry Hills Drive Culex pipiens
3 7/7/14 Martinez I-680 x Waterfront Road Culex tarsalis
4 7/14/14 Discovery Bay Cherry Hills Drive x Marina Road Culex pipiens
5 7/16/14 Discovery Bay Bixler road x Balfour Road Culex pipiens
6 7/17/14 Discovery Bay Cherry Hills Drive x Wayfarer Drive Culex tarsalis
7 7/23/14 Discovery Bay Byron Tract Levee Culex tarsalis
8 8/6/14 Discovery Bay Point of Timber Road x Bixler Road Culex pipiens
9 8/12/14 Discovery Bay Highway 4 x Western Farms Ranch Road Culex pipiens
10 8/13/14 Concord David Avenue x Cayce Court Culex tarsalis
11 8/19/14 Discovery Bay Byron Tract SE Culex pipiens
12 8/19/14 Discovery Bay Byron Tract NW Culex pipiens
13 8/19/14 Discovery Bay Byron Tract NW Culex tarsalis
14 8/19/14 Discovery Bay Byron Tract NW Culex tarsalis
15 8/20/14 Discovery Bay Bixler Road x Point of Timber Road Culex pipiens
16 8/18/14 Discovery Bay Cherry Hills Drive Culex pipiens
17 8/25/14 Discovery Bay Byron Tract NW Culex pipiens
18 8/26/14 Discovery Bay Bixler Rd. x Point of Timber Rd. Culex pipiens
19 8/27/14 Discovery Bay Willow Lake Rd. x Beaver Ln. Culex pipiens
20 9/11/14 Brentwood Orwood Tract Culex pipiens
21 9/16/14 Discovery Bay Agricultural Area Culex pipiens
22 9/22/14 Discovery Bay Byron Tract NW Culex tarsalis
23 10/6/14 Discovery Bay Byron Tract NW Culex pipiens

Dead Birds: 43

n Date Reported City Cross Streets Species
1 4/23/14 Alamo Danville Blvd. x Camille Ave. American Crow
2 5/18/14 Pleasant Hill Monument Blvd. x Mohr Ln. American Crow
3 6/9/14 San Ramon Norris Canyon Rd. x Bollinger Canyon Rd. American Crow
4 614/14 Oakley Empire Ave. x Main St. American Crow
5 6/17/14 Oakley Empire Ave. x Hemlock Dr. American Crow
6 6/17/14 Oakley Empire Ave. x Hemlock Dr. American Crow
7 6/20/14 Brentwood Lone Tree Wy x O’Hara Ave. American Crow
8 6/25/14 Antioch Hillcrest Ave. x Sunset. Dr. American Crow
9 6/26/14 San Ramon Bollinger Canyon Rd. x Norris Canyon Rd. American Crow
10 7/2/14 Bethel Island Bethel Island Rd. x Gateway Rd. American Crow
11 7/9/14 Walnut Creek Arroyo Wy. x N. Broadway American Crow
12 7/10/14 Oakley Kay Ave. x O’Hara Ave. Western Scrub Jay
13 7/13/14 Antioch Camby Rd. x G St. Western Scrub Jay
14 7/14/14 Brentwood Foothill Dr. x Balfour Rd. American Crow
15 7/16/14 Danville Hartford Rd. x Danville Blvd. American Crow
16 7/17/14 Antioch Hargrove St. x E. 18th St. American Crow
17 7/17/14 Brentwood Minnesota Ave. x Windmeadows Dr. Western Scrub Jay
18 7/21/14 Antioch Judsonville Dr. x Hansen Dr. Western Scrub Jay
19 7/23/14 Concord Bancroft Rd. x Hookston Rd. Western Scrub Jay
20 7/29/14 Pinole Mann Drive X Appian Way Western Scrub Jay
21 8/6/14 Concord Ryan Road x Wilmore Avenue American Crow
22 8/6/14 Alamo Stone Valley Road x Roundhill Road American Crow
23 8/7/14 Danville Montcrest Place x Love Lane Western Scrub Jay
24 8/7/14 Discovery Bay Cherry Hills Dr. x Wayfarer Dr. American Crow
25 8/10/14 Concord David Ave. x Getoun Dr. American Crow
26 8/11/14 Brentwood Burghley Ln. x Centennial Dr. American Crow
27 8/20/14 Concord Treat Blvd. x San Simeon Dr. American Crow
28 8/21/14 Walnut Creek Oak Rd. x Jones Rd. American Crow
29 8/21/14 Concord Whitman Rd. x W Gilardy Dr. American Crow
30 8/27/14 Walnut Creek Bancroft Rd. x Treat Blvd. American Crow
31 8/28/14 Danville Harlan Dr. x St. Helena Dr. American Crow
32 9/2/14 Walnut Creek Walnut Ave. x Warwick Dr. Western Scrub Jay
33 9/2/14 Oakley Empire Ave. x Truman Ln. American Crow
34 9/2/14 Brentwood Forest View Common x Central Blvd. American Crow
35 9/4/14 Brentwood Payne Ave. x Walnut Blvd. Western Scrub Jay
36 9/8/14 San Ramon Broadmoor Dr. x Pine Valley Rd. American Crow
37 9/8/14 Orinda Altamount Dr. x Moraga Wy. Stellar’s Jay
38 9/12/14 Danville Verona Ave. x Love Ln. American Crow
39 9/15/14 San Ramon Ascot Dr. x Broadmoor Dr. American Crow
40 9/21/14 Danville Camino Ramon x El Capitan Dr. American Crow
41 9/24/14 Discovery Bay Clubhouse Dr. x Edgeview Dr. American Crow
42 9/29/14 Martinez Glacier Dr. x Olympic Dr. Western Scrub Jay
43 10/8/14 Alamo Royal 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 Bled Area
1/10 6/16/14 Holland Tract
3/10 6/30/14 Holland Tract
1/10 7/14/14 Holland Tract
1/10 7/14/14 Oakley
1/10 7/28/14 Holland Tract
1/10 8/11/14 Holland Tract
1/10 8/11/14 Oakley
3/10 8/11/14 Walnut Creek
1/10 8/25/14 Walnut Creek
1/10 9/22/14 Holland Tract

Horses: 0

n Date Reported City Dead/Euthanized