County Urges West Nile Vigilance

Dead bird with WNV found on 9th Street in Gilroy
Morgan Hill – The bloodsuckers are back and they’ve brought West Nile Virus with them – again.

“There are a lot more infected mosquito pools” this year, said Kriss Costa, spokeswoman for the Santa Clara County Vector Control District. “The good news is, people have been heeding our warnings, using insect repellent.”

In other words, there have been no reported human cases of the dreaded West Nile Virus this year after five people in the county contracted the disease last year. Statewide, 935 human cases were reported in 2005, including 19 fatalities. 

“There could be cases out there that haven’t been detected,” Costa warned, adding that one person who contracted the disease last year was not diagnosed until March.

Saint Louise Regional Hospital spokeswoman Vivian Smith said the virus remains a public health threat.

“We haven’t had a serious earthquake in the past several years, but that doesn’t mean we shouldn’t prepare for it and take precautions,” Smith said. 

Mosquitos are the prime carriers of the flu-like virus, which in rare cases kills infirm humans or leaves victims with lasting neurological damage stemming from inflammation of the spinal chord and brain.

To protect the public against the worst case scenario, the county’s vector control agency last year used $200,000 in state funding to help buy new equipment for fogging in residential areas. The type of poison used, pyrethrin, is derived from the extract of chrysanthemum flowers, which pest control experts believe poses no threat to humans. 

So far, two mosquito foggings have been carried out this summer in west San Jose and Saratoga after more than 80 dead birds tested positive for West Nile Virus. Another fogging in that area is scheduled for Monday.

With August and September believed to be prime-time for mosquitos feeding on humans, vector control workers have also been busy identifying the owners of neglected swimming pools that have turned into mosquito breeding grounds. 

While the virus hasn’t reared its head so much in South County, last week vector control workers responded to a report of a dead crow on 9th Street in Gilroy. The bird tested positive for the virus, Costa said. 

In 2005 there were 144 dead birds discovered countywide. In addition, there were two cases of horses contracting the disease. While the number of dead birds continues to rise this year, Costa said vacinations are to thank for there being no new horse cases.

“There could be more cases (of birds with WNV) we don’t know about” in South County, she said, either because residents aren’t reporting them or possibly because dead birds are harder to discover in rural areas. But the remains of crows, jays and owls should serve as a crucial warning sign that the virus is nearby.

Scientists believe West Nile Virus probably entered the eastern United States in the early summer of 1999. The virus is transmitted by mosquitos and cannot be passed from human to human. Dead birds – especially large raptors – are often the best indication that the virus has entered an area. 

The disease can cause severe illness, lasting neurological effects and even death. The virus can cause severe symptoms in people over 50 and individuals with lowered immune systems. More than 80 percent of people who are infected, however, don’t show any symptoms at all. 

“It’s a risk people have to take seriously,” Smith said, adding that people should limit their outdoor activities at dusk and dawn when mosquitos are most active. “Most importantly” she continued, “seek medical attention immediately if symptoms develop.”

Tony Burchyns covers Morgan Hill for The Times. Reach Him at (408) 779-4106 ext. 201 or tb*******@mo*************.com.