Santa Clara County—For the first time this year, mosquitoes with West Nile Virus have been detected in Santa Clara County, and Oriental Fruit Fly has been found for the second time.
None of the finds was in South County, county agriculture and vector control officials said.
West Nile Virus can be fatal to humans. In 2014, it killed 29 Californians.
The fly can destroy fruit and vegetable crops, including cherries, apricots, peppers and tomatoes. Detection can trigger quarantines, as has happened in Cupertino in late June, that can devastate growers financially.
In 2014, Santa Clara County identified 11 human WNV cases and 925 dead birds tested positive for the disease that is spread by mosquito bites. It was the county’s highest yearly incidence of WNV.
The only human case in South County was in Morgan Hill. None was fatal and only a handful of birds in South County tested positive last year, according to officials.
Discovery of two infected mosquitoes in North County is not cause for alarm, according to Denise Bonilla, manager of the Santa Clara County Vector Control District.
“It’s not worrisome at all,” Bonilla said. “We were expecting it to happen a lot earlier. By this time last year we had done 10 foggings.”
When infected mosquitoes are found, the area around the discovery spot is fogged with insecticide.
“For most people, the risk of serious illness is low,” according to the district’s website. “However, some individuals…can develop a serious neurologic illness, such as encephalitis or meningitis. People 50 years of age or older and people with diabetes and/or high blood pressure have the greatest risk of developing serious complications,” according to the website.
The mosquitoes were found in Palo Alto and Mountain View in the first week of July. Both had the virus “…inside them and ready to inject into a human,” Agriculture Commissioner Joseph Deviney said.
The vector control district relies on citizens to report dead birds, which are tested for WNV. When infected birds are found, traps are set up for mosquitoes.
As of July 8, Santa Clara County had the second highest number of infected birds in the state, 23. The highest was San Diego at 49. The next closest to Santa Clara was Tulare County with 12. All other reporting counties were in single digits, according to state statistics.
The second discovery of Oriental Fruit Fly in the county this year was simultaneously in Los Altos Hills and Los Altos.
It triggered an emergency proclamation by the California Secretary of Agriculture for an eradication program that started July 10. It uses spot applications on trees and utility poles of a pheromone lure that attracts male flies. The flies then ingest and are killed by an insecticide.
The initial program lasted 3 days and involved 14 square miles around the discovery sites. It will be repeated every two weeks for eight weeks, according to county officials.
