HANFORD, Calif. – At 5:45 a.m. on a Wednesday morning, the sun hadn’t come up yet and the air was still chilly, but Medardo Puga had already begun his day.
He put on a backpack that holds a long black tube that looks like a giant vacuum attachment and a white tank containing an insecticide for killing mosquitoes.
“This is our main equipment that we use — a blower,” Puga, an area supervisor with the Kings Mosquito Abatement District, said. “This is what we spray all our fields with. Everything we treat is usually with this."
That’s because activity of West Nile virus — an illness that’s transmitted between animals and humans by mosquitoes — is some of the highest it’s ever been in California.
Health experts say there’s not one clear reason for the surge of mosquitoes, though a previous wet winter, a warm spring this year and changing immunity in wild birds are some reasons health officials point to.
“It is hard to pinpoint one reason why activity is so high,” a spokesperson with the California Department of Public Health told KVPR. “In general, the Central Valley also has environmental conditions that support mosquitoes, with high temperatures in the summer to encourage growth.”
And in Kings County, the virus this season has already proven to be deadly. Of 15 human deaths in the state this year, one was a Kings County resident.
On a typical day, Puga might make 35 stops. He’s out looking for standing water that can serve as mosquito breeding grounds, like a pond.
“The problem at a pond would be all the grass on the edges, like really weedy and dark water, mucky water,” he said.
At one stop in a walnut orchard, Puga and an assistant technician, Angel Gonzales, pulled out a long metal rod with a small white bowl on one end called a dip stick. They scooped up some water from where irrigation pools between the rows of trees.
Inside the bowl were four wriggling mosquito larvae. And those larvae are big trouble.
"We try to treat everything in the water before they become adults,” Puga said. “We try to stay on top of things.”
The district treats breeding sites with a larvicide known as “Censor.” It consists of small granules made from ground-up corn infused with larvicide and is applied to standing water.
To treat the orchard, Puga filled the tank on his backpack with 20 pounds of Censor before yanking on the pull cord and starting its diesel engine. Once the engine was up and running, he and Gonzales walked along the tree lines spraying the larvicide onto the water through the black tube.
“What it does is it targets the insect's nervous system,” Puga said. “It's a one-time kill for the larvae that's in the water.”
Although most people who become infected with West Nile experience mild symptoms such as body aches and fever, severe cases of the infection can cause inflammation in the brain and spinal cord, muscle weakness, and, in some cases, death.
This year in particular has seen a spike in numbers compared to previous years. The number of human cases for the first 9 months of 2026 is already higher than all of 2025.
Mary Beth Danford, an epidemiologist with the California Department of Public Health, says the infection rates in Kings County are among the state’s highest.
“It's about four times higher than what we are seeing in the rest of the state, and that means there's a lot of transmission going on, which means there's a lot of risk for people,” she said.
Czarina Martinez, nursing division manager at the Kings County Department of Public Health, said communities play a role in mosquito control, too.
“One of our greatest concerns that we emphasize with our education is preventing standing water in homes and in the community,” Martinez said. “Standing water really is how the mosquitoes breed and increase the mosquito population and put people more at risk for actually getting bit.”
She also encourages residents to use insect repellent and wear long sleeves during dusk and dawn, when mosquitoes are typically most active.
If a dead bird is found, it can be reported online to the California Department of Public Health or by calling 1-800-968-2473 from April to October.
Health authorities haven’t revealed any information about the Kings County resident who died of the virus. Puga doesn’t know them, either. But he said knowing the stakes of the virus shows him his job is important.
“Before I started, I didn't think it was this serious, how much we really help out the community with everything we do,” Puga said. “I feel good about it. You know, that I’m helping the community in some type of way.”
