Another county in Southern California has confirmed the discovery of mosquitoes carrying the West Nile virus.
His is the first mosquito sample to test positive for the virus this year in Orange County, but according to the state Department of Public Health, 20 of California’s 58 counties have seen West Nile virus activity by 2024.
Orange County has been “pretty lucky this year,” said Brian Brannon of the county’s Mosquito and Vector Control District. In the current heat wave, he noted cooler local temperatures, especially in the evenings, means “we haven’t seen many mosquitoes.”
according to agency, infectious insects found in Huntington Beach during routine testing in the area. West Nile — which can cause symptoms including headache and fever and, in rare cases, can be fatal — is spread exclusively in Southern California by sucking blood. Culex mosquitoes feast at dawn and dusk.
Brannon says there’s no reason to panic. The threat to the public remains low in Orange and Los Angeles counties, where there have been no West Nile-related bird deaths. bird are susceptible to viral infection, and their death will be a sign that the disease is spreading.
The state’s public health department has counted 88 dead birds as positive for the virus so far this year. Santa Clara and Sacramento counties recorded the most birds. Notably, there have been no human cases in California so far in 2024.
Residents who don’t like being bitten can reduce their risk by removing containers of stagnant water from their homes — such as uncovered outdoor grills and potted plants with saucers — where mosquitoes breed. Also, choose long-sleeved clothing and apply a repellent that contains DEET, lemon eucalyptus oil or other effective active ingredients.
Other agencies in Southern California are also on alert, monitoring mosquito species and population numbers, Brannon said.
In the new year, invasive Aedes aegypti has aggressively grown in numbers. These bloodsuckers only need a teaspoon of water to reproduce and, not like that Culex, have a tendency to bite at all hours of the day. They can also spread diseases such as yellow fever, dengue fever and Zika.
“So far this season, we’ve only seen West Nile,” Brannon said, “but we’re looking for other diseases that can spread.”
The Greater Los Angeles County Vector Control District has found three cases of West Nile virus in mosquito samples from the San Fernando Valley, and officials are on the lookout for more because this year’s heavy rains created conditions ripe for mosquito takeover.
“Right now we are still in the normal season. We have not entered the high risk level,” said Susanne Kluh, general manager of the LA County agency. He said these moisture- and heat-loving mosquitoes are usually more active in the Valley.
“The virus grows faster at higher temperatures,” Kluh said, noting that climate change has been a boon for subtropical mosquitoes and the diseases they carry. Mosquitoes have the ability to adapt to “drier or cooler climates,” he added, where they “will continue to be distributed.”
In the spring, vector control agencies in Southern California tested new and innovative methods to stop the spread Aedes mosquitoes – by releasing more. The strategy, as counterintuitive as it sounds, is exciting, said Tristan Alexander Hallum, director of scientific programs at the San Gabriel Valley Mosquito and Vector Control District.
“We started to develop different sterilization techniques to keep the population at bay,” Hallum said. Although it is too early to have data on the effectiveness of these efforts, the idea is that sterilizing male mosquitoes with radiation will begin to reduce the number of eggs they can lay. “Radiation has become a tried and tested method for various programs like flyworm.”
This summer, Hallum said, the fear of catching West Nile or other diseases from mosquitoes shouldn’t stop anyone from participating in outdoor recreational activities.
“I wouldn’t be afraid of persistent mosquito-borne pathogens,” Hallum said. “We’re at routine levels of West Nile virus that’s in our area right now.”