West Nile still active in S.J. County, officials warn

STOCKTON — While the Labor Day weekend typically marks the close of summer, the San Joaquin County Mosquito and Vector Control District is warning residents that West Nile virus remains active in the region.

So far this year, the district has found 313 mosquito samples that tested positive for the virus, the highest in the state, according to westnile.ca.gov.

The last time mosquito samples were this high was in 2016, when the district found 350. That year, district spokesman Aaron Devencenzi said increased rainfall and warmer temperatures contributed to high concentration counts.

Devencenzi noted that having samples test positive does not mean individual mosquitoes carry the virus. A sample, he said, is typically 50 mosquitoes or less from hundreds or thousands captured across the county.

“We’re seeing significant amounts of high concentration in south Sacramento and north San Joaquin counties,” Devencenzi said. “It could be number of things that’s causing the increase, but these increases do tend to be in different areas and in different years.”

While mosquito samples are high this year, there have only been four human cases of West Nile virus in the county this year.

There were 14 human cases of the virus last year and 13 in 2016.

Devencenzi said the number of infected samples collected typically decreases as the fall season nears winter, but he cautioned residents to continue wearing repellent to keep mosquitoes at bay.

“We normally see numbers start to go down as the weather gets cooler,” he said. “But there have been times when we’ve collected samples as late as November. Typically a good frost will take care of them.”

Across the state, there have been 1,296 mosquito samples collected and 42 human cases of the virus reported this year.

Butte and Los Angeles counties have reported six human cases, which are the most in the state. Riverside and Stanislaus counties both reported five cases this year.

Sacramento County has collected 257 samples, and Placer County has recorded 208.

“Going into the Labor Day weekend, we urge people to continue to protect themselves from mosquito bites by using EPA-registered insect repellent day and night, when possible wearing long-sleeved shirts or long pants sprayed with Permethrin and emptying any vessels with standing water,” San Joaquin County Public Health Officer Dr. Kismet Baldwin said.

Public Health and the district advise residents to eliminate any standing water on your property, including flower pots, old car tires, rain gutters and pet bowls, as these can be breeding areas for mosquitoes.

Ensure swimming pools and spas are properly maintained, and consider using mosquito fish in ornamental ponds or fountains.

In addition, both agencies suggest avoiding the outdoors in the early mornings and evenings, which are peak times that mosquitoes are active.

If you must go outside, wear long- sleeved shirts and pants during peak times, and use insect repellent containing DEET to deter mosquitoes, the agencies said.

Report significant mosquito problems to the district at

www.sjmosquito.org, or call 209-982-4675. You can also call 800-300-4675. Report dead birds to 877-968-2473.