Aerial Search for Neglected Swimming Pools in North Santa Clara County Concluded

The Santa Clara County Vector Control District (SCCVCD) has conducted its third and last aerial survey of the season over urban areas in Milpitas, North San José, Santa Clara, Sunnyvale, Mountain View, Los Altos, Los Altos Hill, and Palo Alto on Friday, August 13. This operation  covered approximately 100 square miles to detect neglected swimming pools and other possible sources that could harbor mosquitoes. With this survey, the SCCVCD is completing its 2010 surveillance campaign covering the majority of the Silicon Valley.

 “Despite the lower than average temperatures observed during this summer, the West Nile Virus (WNV) season is still active. Statewide, the number of mosquito samples positive for WNV and the number of human cases are ahead of last year's figures,” said Russ Parman, Acting SCCVCD Manager. To date, the SCCVCD has confirmed 23 WNV positive dead birds, ten positive mosquito samples and three positive squirrels in the County. 

On August 13, a survey plane flew at an altitude of 5,000 feet taking aerial photos. The SCCVCD will review the resulting pictures and determine which pools or other mosquito breeding sources need immediate attention. SCCVCD Technicians will then contact the pool owners to arrange for the pools to be checked and treated if they are developing mosquitoes. A single poorly maintained pool in the backyard can produce millions of mosquitoes. 

Prior surveys conducted in May and June over the southern half of the valley identified over 750 newly detected green or half-empty swimming pools. Following those surveys, SCCVCD staff conducted over 1000 inspections, about 25 percent of which required immediate treatment to eliminate active mosquito breeding.  

Response to the aerial survey program has been encouraging. SCCVCD Technicians who contacted and explained to property owners the health risks posed by poorly maintained swimming pools have noted that most owners take immediate steps to resolve the problem. Consequently, formal legal abatement is seldom necessary. 

View 2010.08.13 Santa Clara County 3rd Aerial Surveillance in a larger map

Preventing  Mosquitoes and West Nile Virus

Transmitted by mosquito bites, WNV can cause mild to severe flu-like symptoms such as fever, headache, and body ache, and, in severe cases, significant neurological symptoms or even death. People over 50 and those with high blood pressure are at higher risk for severe disease. In 2009, California reported 129 WNV infections, with 112 symptomatic cases and 4 human fatalities. While no human cases of WNV have been confirmed in Santa Clara County this year, fogging to suppress WNV-infected mosquitoes is needed to reduce the imminent risk of transmission of the virus to humans. 

Precautions that can be taken against mosquito bites are: 

At home: 

• DRAIN or DUMP standing water weekly since this is where mosquitoes lay eggs. Check items such as flower pots and planter bases, toys, cans, leaky water faucets and sprinklers, rain gutters, buckets, pools, ponds, and old tires. 

• Make sure your DOORS and windows have tight-fitting screens. 

Outdoors: 

• Limit activities during DUSK & DAWN to prevent mosquito bites. Those are the times when the mosquitoes that transmit WNV are most active. 

If you need to go outside at dusk or dawn, or when in an area where mosquitoes are active: 

• Apply insect repellent containing D.E.E.T., Picaridin, or Oil of Lemon Eucalyptus (p-menthane diol), following label instructions. 

• DRESS in long sleeve shirts and long pants, preferably of light colors. 

Dead birds and squirrels may indicate the presence of West Nile Virus. The Vector Control District asks Santa Clara County residents to call if they find crows, jays, sparrows, finches, birds of prey, or tree squirrels that have been dead for less than 48 hours and do not appear to have died because of an injury. Report dead birds and squirrels to the State of California WNV hotline at 877-WNV-BIRD or at www.westnile.ca.gov.  Click here for a flyer with pictures of birds and squirrels of concern.

For assistance on mosquito control, residents can contact the SCCVCD office by calling (408) 918-4770 / (800) 675-1155.