West Nile virus arrived in Fresno County in 2004 and the consolidated district of mosquito control has remained active ever since.
"Every year it's here that we do surveillance, but we still collect West Nile virus mosquitoes in this area," said Katherine Ramirez of the Consolidated Abatement District.
Employees go to neglected pools and pools and use fish or larvicides to control the mosquito population.
But some infected insects always pass through the preventive shield.
This year, they collected 46 Culex mosquitoes carrying serious viruses.
43 had West Nile virus; three had encephalitis from St. Louis.
"We are doing a very low-volume spraying in an area where we find infected mosquitoes, and we are continuing to monitor to make sure the mosquito population has been reduced," Ramirez said.
He has kept people in Fresno County safe so far this year.
But their collection of infected Culex mosquitoes has now spread to Fresno, Clovis and Sanger, exposing people to the risk of getting infected and causing problems ranging from flu-like symptoms to paralysis and tremors.
And the mosquito Aedes aegypti can be even worse.
They can carry chikungunya, yellow fever, dengue and zika. They are much more hungry than Culex mosquitoes, who could eat blood every two weeks.
"It is an extremely harmful mosquito and it will bite several times, so, often, someone thinks they have a huge mosquito problem because of the perception of the number of bites," Ramirez said.
The Mosquito Control District has teamed up with a Google arm for an experiment to reduce Aedes aegypti, shedding sterile male mosquitoes in neighborhoods and giving positive results.
They say they have detected 95% fewer females in these areas and that they are the only biting mosquitoes.
The bites are still there, however, an insect repellent is a necessity, especially at dusk and at dawn.
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