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West Nile Virus and Mosquito Control Awareness Week

County of Santa Clara Vector Control District Launches Expanded Mosquito Surveillance, Asks Residents to Watch for Invasive Vectors
SANTA CLARA COUNTY, CALIF. – The California State Legislature has declared the week of April 22nd as “West Nile Virus and Mosquito & Vector Control Awareness Week” in California.  This week, the Santa Clara County Vector Control District (the District) announces the beginning of its expanded seasonal efforts to monitor mosquito breeding sources and West Nile virus (WNV) activity.
West Nile virus is a disease transmitted by mosquitoes that can result in debilitating cases of meningitis and encephalitis, and could lead to death in humans, horses and birds.  Using a state-of-the-art system, the District will conduct an aerial survey of urban areas in South San Jose today.  This operation will cover approximately 78 square miles and is designed to identify neglected swimming pools and other possible mosquito-breeding sources. The area to be surveyed is last season’s WNV hotspot, which persisted for six weeks and resulted in one severe but non-fatal human case.
“We have detected WNV activity as early as February this year, and we are expecting another very busy summer,” noted acting District Manager Russ Parman. “Last season’s human case underscores the need to continue our surveillance and control operations to minimize the risk of getting WNV.”
A single poorly maintained pool in a backyard can produce millions of mosquitoes during the warm season.  Since 2007, the District’s aerial surveys have cataloged over 4,000 locations with neglected pools.  Almost half of the mosquito control treatments applied to these properties have consisted of free delivery and planting of mosquito fish, which eat immature mosquitoes.
The District has also placed seven flocks of chicken in strategic areas across the county to monitor WNV activity.  When WNV infected mosquitoes feed on the chickens, the chickens will develop antibodies and thus act as a good indicator of local virus activity. 
This year’s late rainy season may result in more standing water in warmer temperatures, which could encourage mosquito breeding. As always, the eyes of the public are critical to help the District keep mosquito numbers low by watching out for standing water, and reporting larger breeding sources such as swimming pools. To help control mosquitoes, the District is asking residents to take the following steps:
  • Make sure that doors and windows have tight-fitting screens.  Repair or replace screens that have tears or holes;
  • Flip or dump small containers collecting water;
  • Contact the District if you are being bothered by mosquitoes during the day;
  • Contact the District if you know of a potential mosquito-breeding source; and
  • Report dead birds to the State of California WNV hotline at 877-WNV-BIRD or at
Dead birds may indicate the presence of WNV.  The District has laboratory facilities to test for WNV and other vector-borne diseases.  The District asks Santa Clara County residents to report crows, jays, sparrows, finches, or birds of prey that have been dead for less than 48 hours and do not appear to have died because of an injury.  People who find those birds should call the State of California WNV hotline at877-WNV-BIRD (2473) or at
 “Our technicians are surveying public areas; we need the eyes of the residents to help us promptly respond if this mosquito shows up in our county,” said José Colomé, Community Resource Specialist for the District.  
For free assistance on mosquito control, WNV, or other vectors, residents can contact the District office by calling (408) 918-4770/(800) 675-1155, or fill out a service request form online at

Asian Tiger Mosquito
This year, a large-scale effort is underway in Southern California to eradicate the Asian Tiger Mosquito, an invasive mosquito species and a major transmitter of Dengue fever and Chikungunya virus.  The District is monitoring the situation and asking residents to report if they find ATM in Santa Clara County.
Asian Tiger Mosquito differs from other local mosquitoes: it is smaller, tends to bite during the day, and has very distinctive black and white markings, including a prominent stripe running down the back. They also breed in small containers such as cans, flasks, saucers and plant leaves holding water.  The local treehole mosquito, which also bites during the day and is small, breeds in trees and lacks the white stripe down the back.


The District has successfully eradicated two invasions of ATM in the past decade.  In 2001, a greenhouse in Gilroy was infested by a shipment of “lucky bamboo” from Southeast Asia.  In 2003, ATMs were detected in a greenhouse in Mountain View, and had spread about a quarter mile outside of the nursery. 
Media Contact: Russ Parman 408-593-6176 English; Noor Tietze 408-210-5773 English; José Colomé 408-210-5774 English and Spanish
Posted: April 23, 2012