Modesto neighborhood sprayed for mosquito that can spread Zika virus

A female Aedes aegypti mosquito, known to be a carrier of the Zika virus, acquires a blood meal on the arm of a researcher.
A female Aedes aegypti mosquito, known to be a carrier of the Zika virus, acquires a blood meal on the arm of a researcher. Associated Press

A mosquito that can spread Zika virus is now a confirmed resident of Stanislaus County and will require annual monitoring and a commitment of resources to keep it in check.

Early Friday morning, the East Side Mosquito Abatement District sprayed a 450-acre area of east Modesto for Aedes aegypti mosquitoes, which are able to transmit Zika and other diseases such as dengue and chikungunya.

The first mosquito was found in a trap July 25 just north of the intersection of Lakewood Avenue and Scenic Drive. A second mosquito, confirming a likely breeding population, was discovered nearby Wednesday.

District staff fogged the streets and alleys east and west of the intersection and north to East Orangeburg Avenue, said Wakoli Wekesa, general manager of East Side. The district plans to resume control measures Monday and conduct surveillance to determine the extent of the infestation.

Control technicians going door-to-door last week did not find any more of the invasive mosquitoes. But Wekesa said he wouldn’t be surprised if the additional traps set out will pick up more of them.

The Aedes aegypti species has been detected in Merced, Fresno and other counties in the San Joaquin Valley. Local officials had felt it was just a matter of time before the mosquitoes would surface here.

“Looking at what’s happened in the area from Merced south to Fresno and Madera most likely there are more (in Stanislaus County). And we don’t know how long they have been here,” Wekesa said. “I am sure the more we look, the more we will find.”

Local agencies advised caution and want the public to understand the mosquitoes are here. But there is little or no current risk of people coming down with Zika or one of the other viruses.

Zika, which causes miscarriages in pregnant women and severe birth defects, is not being transmitted in California or anywhere in the nation. Infection could possibly occur if a traveler infected in a country that has Zika cases returns home to the Valley and the virus is transmitted to another person by mosquito bites.

Vector control districts that deal with Aedes aegypti keep them in check with regular monitoring and control measures, Wekesa said. By keeping their numbers down, it eliminates or lowers the risk that any infected mosquitoes could transmit illness to people.

“It just adds an additional need for resources to keep that monitoring in place,” said Wekesa, who began work for East Side a month ago, coming from Coachella Valley Vector Control District.

The Aedes aegypti species are known for biting aggressively during the day. To help with tracking the species, residents are encouraged to report that behavior to local abatement districts.

“If you are sitting in your back yard during the day and getting bit, we want to know about it,” said David Heft, general manager of Turlock Mosquito Abatement District.

Heft said the district will expand its surveillance for Aedes aegypti and inform the public through advertisements on Turlock buses.

As of early July, the mosquitoes also had been detected in Merced and Los Banos, a dozen counties and numerous cities throughout Southern California, according to information from the California Department of Public Health.

Stanislaus County residents north of the Tuolumne River can report mosquito problems to East Side Mosquito Abatement District at 209-552-4098. Other residents may call Turlock Mosquito Abatement District at 209-634-1234.

Ken Carlson covers county government and health care for The Modesto Bee. His coverage of public health, medicine, consumer health issues and the business of health care has appeared in The Bee for 15 years.