Mosquitoes carrying West Nile virus have increased in the Elk Grove area, and authorities are boosting efforts to control their spread, the Sacramento-Yolo Mosquito and Vector Control District said Monday.
Most mosquitoes testing positive for the virus were trapped south of Elk Grove, between Interstate 5 and Highway 99 and between Laguna Boulevard and Twin Cities Road, district manager Gary Goodman said in a statement.
Parks in the zone are being fogged, and any areas of standing water that might be breeding grounds for mosquitoes are being treated, said district spokeswoman Luz Robles.
The virus has not been as common this year compared to last, Robles said, but it is still early in the season. The disease is transmitted when culex mosquitoes bite infected birds.
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So far in Sacramento County, 63 mosquito samples and 37 dead birds have tested positive for West Nile virus. In Yolo County, 25 mosquito samples tested positive.
The vector control group also warned Monday of another disease carried by the same species of mosquito called St. Louis encephalitis that is “re-emerging throughout the state,” showing up in Placer, Yuba and Stanislaus counties in recent weeks. Mosquitoes in Sacramento and Yolo counties have not tested positive for St. Louis encephalitis.
Upticks in the number of mosquitoes carrying West Nile virus are common in late summer. Symptoms include fever, headache, nausea, vomiting and fatigue and, in older people, inflammation of the brain, according to the U.S. Centers for Disease Control and Prevention. The disease can escalate to convulsions, vision loss and paralysis. St. Louis encephalitis can cause similar symptoms. Although many people who contract the disease do not become sick, it can be fatal in certain cases.
So far, no human cases of West Nile virus or St. Louis encephalitis have been reported in the area.
To prevent mosquito-borne disease, the vector control district recommends draining still water that could turn into a breeding ground for the insects as well as avoiding contact with mosquitoes by staying indoors around dawn and dusk, dressing in long sleeves and pants and using insect repellant.
“We’re not out of the woods yet, so we’re encouraging people to make sure they’re protecting themselves from mosquitoes,” Robles said.