West Nile virus cases on the rise in Santa Clara County

Santa Clara County is experiencing a rise in West Nile virus cases, which mosquitoes transmit.

So far, treatments in neighborhoods have increased over 20% from the same period last year, according to the county.

The uptick is a concern for the county's vector control district and the public health department.

A spraying operation is scheduled for next Wednesday in San Jose, marking the ninth time this summer that special trucks will be used to deploy pesticides. That’s up from seven at this same time last year.

"We are alarmed," said Edgar Nolasco, director of the county's Consumer and Environmental Protection Agency, which includes the vector control district.

With the mosquito season stretching from June to October, the county fears a possible record-breaking year for West Nile cases.

"This year, unfortunately, we are seeing an increase in humidity and an increase in heat and previously we had a rainier season, so that is increasing our West Nile activity in the county," Nolasco explained.

Vector control uses specialized traps to capture and examine mosquitoes. Whenever a county lab confirms a mosquito carrying West Nile, spraying is conducted within a one-mile radius of the location.

The county has mailed out 80,000 fliers to residents informing them of spray operations in their neighborhoods.

The uptick is also placing public health officials on high alert.

"That definitely does make us concerned about the risk to humans," Dr. Monika Roy of the Santa Clara County Public Health Department said.

The county has had two confirmed cases of West Nile transmission to humans, and one of them resulted in a death.

Due to the increase in West Nile, public health officials have informed county medical professionals to consider testing for the virus.

"Commonly people will experience flu-like symptoms, fever, headache, muscle aches. When it becomes more severe we see neurologic manifestations like confusion, coma, things like that.," Roy said.

Officials advise residents to eliminate any standing water to prevent mosquitoes from breeding.