In their latest try and eradicate an invasive mosquito species discovered last month, Santa Clara County officials will spray an east San Jose neighborhood with a bacterial spray next week.
Since early April, district officials have discovered 12 female Aedes aegypti mosquitoes in a residential area near Machado Lane, off Story Road. These mosquitoes are invasive in the world and may transmit various diseases, similar to Zika, dengue fever, yellow fever or chikungunya. Zika will be especially dangerous for pregnant women, as it may cause birth defects and problems for the newborn.
“It's a challenge, but we're trying our best to make sure this mosquito doesn't take hold,” Nayer Zahiri, director of the Santa Clara County Vector Control District, said at a news conference Friday.
On Wednesday morning, authorities said they may spray the world with a pesticide that controls the mosquitoes' larvae. The treatment, referred to as a large-scale larvicidal spray, takes two hours and is derived from naturally occurring bacteria which are nontoxic to humans, helpful insects and other wildlife. The county plans to spray the world several times over the subsequent few months.
Zahiri said the threat from the mosquitoes stays low and that the rare cases of Aedes aegypti-related illness within the county have come from individuals who have traveled to places where the mosquito is endemic or established. Since April, the issue area has expanded to about 118 acres of the East San Jose neighborhood and includes greater than 250 properties, said Noor Tietze, scientific technical services manager for the Santa Clara County Vector Control District.
County officials previously responded to the infestation with surveillance efforts, with staff setting traps along Machado Lane, inspecting properties for mosquito larvae and standing water, and removing any larvae.
Two of the invasive pests were found on the Newby Island Landfill in Santa Clara County in October 2022 and were quickly eradicated.
But the recent infestation in a residential area is harder to eradicate, said Edgar Nolasco, director of the Santa Clara County Department of Consumer and Environmental Protection. According to a county news release, more mosquitoes were present in an area with a whole lot of people – and ahead of the warmest months of the 12 months when mosquitoes are more energetic.
“Controlling the population is not easy because the Aedes aegypti mosquito adapts to any environment and bites other mosquitoes, making it difficult to control,” said Zahiri. “Reproduction is another challenge because they prefer to lay their eggs in small containers, making it difficult to find all breeding sources.”
Aedes aegypti mosquitoes are about 6 mm long and will be identified by the black and white stripes on their bodies and legs. Their eggs are tiny and may seem like grains of dirt to the naked eye. These mosquitoes prefer to put their eggs above the water line in small, artificial water sources similar to buckets, animal bowls, fountains and water baths, flower pots and saucers, and old tires.
County officials said they don't know the way the mosquitoes got to East San Jose. They suspected the insect's eggs can have been unknowingly transported to the world — which is feasible for the reason that eggs can survive without water for a minimum of a 12 months.
The Aedes aegypti mosquito species is dangerously persistent and tends to be energetic throughout the day and bite multiple times, officials said. They only move a couple of block from where they breed, making it imperative for people to eliminate standing water where the mosquitoes could potentially breed and spread.
County officials really helpful cleansing and scrubbing birdbaths, pet bowls and other containers to remove any eggs that could be present, and urged residents to rigorously screen rain barrels, cisterns and irrigation canals to stop mosquitoes from entering.
County officials also really helpful that individuals protect themselves from mosquito bites by applying insect repellent with EPA-registered ingredients similar to DEET, picaridin, IR3535 or lemon eucalyptus oil, following label directions. They also really helpful that individuals wear long-sleeved shirts, pants, socks and shoes when mosquitoes are most energetic and be sure screens on windows and doors are in good condition.
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