Bird carrying West Nile found in south county

San Joaquin County has logged its first signs of West Nile virus activity this year. A dead wild finch collected near Ripon has tested positive for the virus.

“This is the first find of WNV activity in San Joaquin County for 2021,” said Aaron Devencenzi, spokesman for the San Joaquin County Mosquito and Vector Control District. “With warm weather, mosquito populations will continue to increase, leading to an elevated risk of WNV in humans.”

To help prevent the spread of West Nile virus within the county, the district is calling on county residents to eliminate or treat any standing water on their property. Mosquitofish are available for use in water sources that cannot be treated or removed; they eat mosquito larvae that live in the water.

Additionally, the district recommends that county residents:

• Apply insect repellent containing EPA-registered active ingredients, including DEET, Picaridin, oil of lemon eucalyptus, or IR3535, according to label instructions, when outdoors. Repellents keep mosquitoes from biting.

• Avoid spending time outside when mosquitoes are most active, at dawn and dusk, especially for the first two hours after sunset.

• When outdoors, wear long pants, loose-fitting long-sleeved shirts, and other protective clothing when possible, especially during times mosquitoes are more active.

• Keep mosquitoes out of your home with tightfitting screens on doors and windows.

• Contact their veterinarian for information about protecting dogs and cats from mosquito-borne parasites like heartworm, and vaccinate horses against West Nile virus and Western Equine encephalitis.

Last year, San Joaquin County had no human cases of West Nile virus. However, the county saw four equine cases in 2020. Four dead birds recovered and tested within the county in 2020 were found to be carriers, and 260 mosquito samples tested positive for the virus.

Mosquitoes carrying St. Louis encephalitis were also identified in Lodi last August, and in November, San Joaquin County saw its first reported human case of the virus since 1973.

Additionally, the district identified invasive Aedes aegypti mosquitoes in the Stockton area in 2019 and 2020. The invasive pests — known to bite during daylight hours — can spread quickly and carry a number of diseases.

Any mosquito infestations or daytime-biting mosquitoes should be reported to the district. For more information, to request mosquitofish, or to report an infestation, call 209-982-4675 or 800-3004675, or visit www.sjmosquito.org.

Residents are also asked to report any dead birds, which can help the district and the state track potential West Nile virus “hot spots.” To make a report, call 877968-2473 or visit westnile.ca.gov.