The Santa Clara County Vector Control District has confirmed the presence of West Nile virus-positive mosquitoes in a small area that includes Sunnyvale and Santa Clara, and weather permitting, those areas will be treated to reduce adult mosquito populations.
The treatment will be carried out using truck-mounted equipment on Thursday, August 3, starting around 10:00 p.m. and lasting approximately 4 hours. The affected codes will be: 94085, 94086, 94087 and 95051.
Authorities have noted that there is no need to change locations during treatment as these pose minimal risk to people, pets, animals and the environment when applied by a licensed vector control professional following label instructions.
However, they said, those who wish to take extra precautions can keep family members and pets inside during the roughly four-hour treatment, with windows and doors closed.
In the morning, the insecticide breaks down rapidly when exposed to sunlight. Since the District applies insecticides at ultra-low volume, people are unlikely to breathe or touch anything that has enough insecticide on it to be harmful.
"All materials used in our mosquito control program are approved by the Environmental Protection Agency for use in public areas and are widely used by vector control agencies throughout California," officials said in a statement.
The District's mosquito management program focuses primarily on preventing mosquitoes from reaching the adult biting stage by proactively targeting immature stages of mosquitoes found in standing water.
When a mosquito is detected that is positive for the West Nile virus (WNV), it is crucial that control treatments be carried out, since any delay in application would present an imminent threat to public health and safety, exposing the community to possible injuries, or even death, caused by a vector.
It is normal to see an increase in West Nile virus during the summer and early fall because mosquitoes thrive in warm climates.
Santa Clara County officials are sending notice directly to the public in treatment ZIP codes through AlertSCC and to those who subscribe to Nextdoor. Additionally, they have issued a general notice on several social media platforms, including Facebook, Instagram and Twitter ‒@SCCVCD‒, and to those subscribed to the District’s mosquito treatment notifications.
Vector Control staff will be available to answer questions from the public, Monday through Friday, on their dedicated West Nile virus hotline at (408) 282-3114, from 7:30 a.m. to 3:30 p.m. Questions can also be submitted by email to vectorinfo@cep.sccgov.org.
Since West Nile virus arrived in California in 2003, more than 7,000 people statewide have contracted the disease; nearly 400 of those cases were fatal. In 2022, there have been 15 human deaths related to WNV; 2015 was a record year for deaths in the state with 55 deaths.
WNV infection causes no symptoms in most people. However, in some people it can cause fever, headache, body aches, and in severe cases, significant neurological damage or death. People with certain chronic medical conditions — such as diabetes, high blood pressure, cancer, and kidney disease — and older adults are at higher risk for serious complications.
To prevent this, inspect weekly for standing water; drain or turn over anything that can hold water, such as flower pots, planter stands, pet dishes, buckets, and old tires; clean items such as birdbaths and pet feeders once a week to remove mosquito eggs; and clean debris from rain gutters regularly to allow water to flow away.
Also, properly cover rain barrels, cisterns, and irrigation drains to prevent mosquito access; repair leaky faucets and broken sprinkler heads and avoid overwatering lawns and plants; make sure window and door screens are in good condition, free of holes or tears, and tight-fitting; and check that the pool water level is adequate for proper circulation and filtration.
Free mosquito fish can be ordered online at www.sccvector.org for placement in pools/spas, ornamental ponds, watering holes, and other neglected man-made bodies of water.
Outdoors, limit outdoor activities during dusk and dawn—these are the times when mosquitoes that transmit WNV are most active; dress in long-sleeved shirts and long pants, preferably in light colors—mosquitoes are primarily attracted to dark colors; apply insect repellent containing DEET, IR3535, or oil of lemon eucalyptus, always following label directions.
Finally, contact the Santa Clara County Vector Control District if you are bothered by mosquitoes or know of a possible breeding source for mosquitoes.
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