FRESNO COUNTY, Calif. (KFSN) — Fresno County is among nine counties in California reporting West Nile virus activity in 2026, with cases detected through infected mosquitoes and dead birds, officials said.<\/p>\n
Health experts warn the public to prepare now, as virus activity is expected to increase in the coming months as summer approaches.<\/p>\n
With warmer weather approaching, mosquito control officials say some mosquitoes in Fresno County have already tested positive for the virus. Katherine Ramirez, director of science and outreach at the Consolidated Mosquito Abatement District, said early detection signals that more cases are likely.<\/p>\n
“They’ve been collecting positive mosquitoes down south for a few weeks, and so it’s just a matter of time,” Ramirez said.<\/p>\n
Ramirez said her team regularly collects and tests mosquito samples to monitor for infectious diseases. Through that process, mosquitoes in the Harlan Ranch area were identified as carriers of West Nile virus.<\/p>\n
In response, crews plan to spray within a quarter-mile radius of where the infected mosquitoes were found.<\/p>\n
“We are going to go and spray that in that neighborhood, so within a quarter mile around the positive mosquitoes, but just because we didn’t find positive mosquitoes in other areas doesn’t mean residents are safe,” Ramirez said.<\/p>\n
Officials said mosquito activity – and the risk of infection – is expected to increase as summer nears. About 40% of people infected with West Nile virus may experience flu-like symptoms, while roughly 1% are at risk of developing severe illness.<\/p>\n
Residents in affected areas may see white spray trucks operating in their neighborhoods. The vehicles are equipped with systems designed to attract mosquitoes and kill them on contact.<\/p>\n
“We have a spray rig on the back of the truck, and there’s a beacon, so it’s a yellow light that’s on the top of the truck, and we just spray, we drive throughout the neighborhood at a very low rate, and then we just kind of make a zigzag throughout the neighborhood,” Ramirez said.<\/p>\n
Despite these control efforts, officials stress that residents must also take steps to reduce their exposure to mosquitoes. Recommended precautions include using insect repellent when outdoors and eliminating standing water around homes, which can serve as breeding grounds.<\/p>\n
Ramirez noted that yard drains are among the most commonly overlooked sources.<\/p>\n
“It’s usually in the yard, front and back, and there isn’t really anything we can do. They can produce mosquitoes all summer, so just a little bit of window screen under the cap will prevent mosquitoes from going in and out,” she said.<\/p>\n
In addition to local mitigation efforts, Google’s parent company, Alphabet, has proposed releasing 32 million male mosquitoes across California and Florida as part of a program to reduce mosquito populations. The male mosquitoes, which do not bite, carry a bacterium that prevents reproduction when they mate with females.<\/p>\n
“When they mate, she’s essentially, essentially sterile, so she still lays eggs, but those eggs don’t hatch, and so that’s going to reduce the population,” Ramirez said.<\/p>\n
A similar program was tried in Fresno in 2018, though it is not yet known whether the Central Valley will be included in this year’s rollout.<\/p>\n
Officials emphasized that mosquito control treatments used by the district are not toxic to humans. Anyone who believes they may have contracted West Nile virus is advised to seek medical attention.<\/p>\n
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