The Centers for Disease Control and Prevention announced in a July 1 press release that 2026 saw “the earliest start to the West Nile virus season in the United States with the highest number of human disease cases reported by this time of year since 2004.”
Meanwhile, the Delta Mosquito & Vector Control District, which oversees mosquito control in northern Tulare County, including Visalia, Dinuba, Exeter, Farmersville, Woodlake, Cutler, Orosi and Ivanhoe, reported a slower start than usual this year.
The district confirmed the first detection of the West Nile virus in mosquito samples in the area on June 25 when two mosquito samples tested positive for the virus in Dinuba, and one was collected just north of Visalia. This marks a later detection of the West Nile virus than in most years, according to the district.
“It’s a little slow this year,” said Erick Arriaga, district community education and outreach coordinator. “There’s no real answer on why it’s slow, and the answers aren’t clear either for the years where it’s really busy at the beginning.”
It was suggested that the reason might be that it hasn’t been as hot in the valley this year as in recent years, while it’s been hotter than usual almost everywhere else in the country.
“I know our overnight temperatures have a lot to do with how quickly the life cycle for the mosquito goes, and it’s been in the low to upper 60s sometimes,” Arriaga said. “That means that overnight whatever mosquitoes are in the water develop slower, and slower development means the populations rise more slowly.”
The worst is yet to come
Even though the area is off to a slow West Nile virus season this year, the worst part of the season is yet to come.
Late July and all of August is the peak season in Tulare County because of how hot it is in August, Arriaga said.
“How high the peak depends on just how well the public does on reducing water sources in their homes,” he said. “This year, we’ve done a pretty good job taking care of all the unmaintained pools, and that might be part of the reason the season has a slower start, but all of our initial treatments in April and May for these pools could go away by July and August.”
West Nile virus prevention guidelines
West Nile virus is most commonly spread through the bite of an infected mosquito. Most people infected with the virus do not develop symptoms, but some may experience fever, headache, body aches, joint pain, vomiting, diarrhea, or rash. In rare cases, the virus can cause serious neurological illness.
The Delta Mosquito & Vector Control District advises people to follow these guidelines to reduce the risk of contracting mosquito-borne diseases such as West Nile virus:
This article originally appeared on Visalia Times-Delta: West Nile virus season gets late start in Tulare County
Reporting by Steve Pastis, Visalia Times-Delta / Visalia Times-Delta
USA TODAY Network via Reuters Connect
By Steve Pastis, Visalia Times-Delta | USA TODAY Network
