The Control District Santa Clara County Vectors has confirmed the presence of West Nile virus-positive mosquitoes in a portion of San Jose and Milpitas.
The authorities have detailed that, weather permitting, these areas will be treated to reduce adult mosquito populations with the use of truck-mounted equipment next Monday, September 11, beginning around 10:00 p.m. and concluding on two four hours later.
The District's mosquito control program focuses primarily on preventing mosquitoes from reaching the adult biting stage by proactively attacking immature stages of mosquitoes found in standing water.
However, when a mosquito with West Nile virus is detected, the District takes the additional step of performing control treatments on adult mosquitoes.
The District specified in a statement that it is essential that adult mosquito control treatments be carried out as quickly as possible upon finding a positive mosquito, as any delay in the application would present an imminent threat to public health and safety, exposing the public to potential vector-borne injury or even death.
It should be noted that adult mosquito control treatments reduce the mosquito population in the area, which decreases the risk of human infection by West Nile Virus.
According to studies, it's normal to see an increase in West Nile virus during the summer and early fall because mosquitoes thrive in warm weather.
Given this, the District said it has a surveillance program dedicated to detecting the presence of diseases such as West Nile virus, St. Louis encephalitis and Western equine encephalitis, all of which are transmitted by the bite of infected mosquitoes.
The data collected through surveillance is used to predict locations most likely to have these disease-carrying mosquitoes.
In turn, the District noted that it has been conducting regular truck-mounted adult mosquito control treatments since 2003 to successfully reduce populations of West Nile virus-transmitting mosquitoes.
The Vector Control District highlighted that it is not necessary to relocate during the treatment to control adult mosquitoes, as these represent a minimal risk to people, pets, animals and the environment when applied by a licensed professional.
However, he said, those who wish to take extra precautions can keep family members and pets inside during the roughly four-hour mosquito-control treatment, with windows and doors closed.
In the morning, the pesticide breaks down quickly when exposed to sunlight. Since the District applies ultra-low volume pesticides, it is unlikely that people would breathe in or touch something that has enough pesticide on it to be harmful.
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 were 15 West Nile virus-related human deaths; 2015 was a record year for deaths in the state with 55 deaths.
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