Invasive Aedes mosquito species found for first time in county, spawning health concerns
People encouraged to report suspected Aedes aegypti bites on mosquito hotline
Tom KiskenA potentially dangerous species of mosquito not found before in Ventura County has emerged in Simi Valley with more people reporting bites every day.
"We are being flooded with calls," said Ron Ventura, supervisor with the Ventura County Environmental Health Division. "We’re getting a dozen calls a day at least."
The small black mosquito with white stripes on its back and legs is called Aedes aegypti or yellow fever mosquito. Found in Kern and Los Angeles counties and long suspected of having crossed into Ventura County, the aggressive day-biting insect was found in Simi Valley on Sept. 9 after a resident reported being bitten.
The mosquitoes generate concern because they have the potential to transmit dangerous viruses including Zika, dengue, chikungunya and yellow fever.
Aedes mosquito concerns officials
Though the invasive Aedes have been found in rising numbers across California, state public health officials say there have been no known cases of mosquito transmission of Zika or the other illnesses.
Officials are concerned the mosquitoes could become carriers by biting returning travelers who were infected in other parts of the world where the viruses are more common including Central America, Mexico and Asia.
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The first Aedes aegypti in Simi Valley was found south of Sycamore Drive and Fitzgerald Road. The mosquitoes have also been discovered in eastern regions of the city.
As of Monday morning, 15 of the insects had been trapped, all in Simi.
Ventura urged residents to call the mosquito hotline at 805-658-4310 if they believe they've been bitten.
"We want to identify as many neighborhoods in Simi Valley to figure out the extent of the infestation," he said, noting the species is unusual because it often bites during the day.
"This is a very aggressive mosquito," Ventura said. "A female would bite about 30 times looking for a blood meal."
Environmental health workers are inspecting sites in the vicinity of where the mosquitoes have been reported in a process complicated by COVID-19 and involving masks and social distancing.
Emphasizing there has been no known mosquito transmissions in California of Zika or the other viruses linked to the invasive Aedes, Ventura said people should contact their doctors if they become sick or have adverse reactions to bites.
They should also protect themselves by eliminating any standing water that could serve as a breeding ground. The mosquitoes lay their eggs just above the water in containers like dishes under potted plates, bird baths, tires, ornamental fountains and children's toys.
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What else to know about Aedes aegypti mosquito
The invasive Aedes can breed in very small places like water that is cupped by certain plants or in open lids and caps. Dump out any water and get rid of the containers that held it, Ventura said.
The mosquitoes can be found indoors too.
"This mosquito has an affinity for humans. They’ll establish and breed in their homes," he said, emphasizing the importance of repellent, tight-fitting screens and snug doors.
Eliminating the water is a primary purpose of the site inspections. Ventura said sites may also be treated with pesticides.
Another mosquito species found in California and linked to Zika and other viruses is Aedes albopictus, known as the Asian tiger mosquito. That species has not yet been discovered in Ventura County but has been found in Los Angeles County.
"It’s possible," said Ventura of the presence of the species locally. "We always felt the invasives were here in Ventura County."
The insects that emerge each year in Ventura County and can carry West Nile Virus are several species of the Culex mosquito. Though the West Nile season often begins in September, there have been no confirmed reports of the virus in animals or people in Ventura County so far.
For protection against all mosquitoes, people should remove standing water and protect their homes with screens. They should wear long sleeve shirts, long pants, socks and shoes.
Ventura said they should also use an EPA-approved insect repellent.
Tom Kisken covers health care and other news for the Ventura County Star. Reach him at tom.kisken@vcstar.com or 805-437-0255.
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