South Bay attacks West Nile Virus with fogging

Vector control workers will be spraying a “very small amount of pesticide” through parts of the South Bay this week after the West Nile Virus was detected in the area.

Officials said the ground fogging is scheduled for Wednesday night and early Thursday morning in a mostly residential area where the cities of Sunnyvale, Santa Clara and Cupertino share borders.

The fogging comes after the West Nile Virus — transmitted to humans by mosquito bites — was confirmed last week after tests were run on adult mosquitoes collected in the area.

It’s the district’s third fogging campaign of the year.

Acting Santa Clara Vector Control District Manager Russ Parman said in a statement:

“This is the third indication of [West Nile Virus-infected] mosquitoes in Santa Clara County this year, the June 4th fogging date matches the prior first-fogging record.”

According to the Centers For Disease Control and Prevention, there are no medications or vaccines to prevent or treat West Nile virus.

Though most people infected with the virus have no symptoms, some become very ill with severe flu-like symptoms such as fever, headache and body aches.

In severe cases, there’s significant neurological damage or even death. The elderly and those with compromised immune systems are most susceptible.

Since West Nile Virus was first detected in California in 2003, 145 people have died from the virus.

Noor Tietze, the district’s scientific technical services manager said:

“This unusually intense [West Nile Virus] season underscores the need for residents to protect themselves from mosquito bites, and to eliminate standing water on their properties.”

To kill the mosquitoes, a truck-mounted fogger will mist microscopic droplets containing a mosquito control treatment called Zenivex.

The product, approved by the Environmental Protection Agency (EPA), is considered “an effective insecticide used at low volumes to control adult mosquitoes.”

The fogging will take place roughly north of I-280 and straddle a section of El Camino Real. It is scheduled to begin Wednesday at 11 p.m. and expected to last several hours.

Vector control officials said there should be no significant risk to people living in the area, and there is no need for residents to leave their homes during the fogging.

In a statement last November, the EPA’s Office of Chemical Safety and Pollution Prevention noted Zenivex was approved for use over agricultural crops — including those intended for human consumption — as well as over pasture and rangeland.

The office said the pesticide provides a quick permanent knockdown of adult mosquitoes, but warned it is toxic to aquatic organisms, including fish and aquatic invertebrates.

It is also “highly toxic” to bees exposed to direct treatment on blooming crops or weeds.


John Marshall is an SFBay editor and producer and writer for San Francisco’s KGO Radio.  Follow him on Twitter @breakingnewsman.