West Nile Virus is on slight decline

The West Nile Virus appears to be having an off-season in the South County, according to biologist John Albright of the Shasta Mosquito and Vector Control District. Albright has found only one dead crow in Happy Valley whose demise can be attributed to the virus.

"Not a lot of dead birds are showing up," Albright said Wednesday, Aug. 5. "I'd have expected we would have a lot more by now."

The sentinel chickens agree.

The district keeps chickens cooped at various locations throughout Shasta County, including one coop in Happy Valley and another east of Cottonwood. They operate as a sort of canary in a mine shaft indicator for the virus. Albright said the district takes blood samples from the chickens to check for an increase in antibody levels.

The chickens do not get sick from WNV, he said. The chickens do, however, lay more eggs than the small staff at the district can consume.

"With 53 chickens laying an egg a day - we can only eat so many," Albright said, adding that leftover eggs are donated to Shasta Wildlife Rescue and Rehabilitation.

The district also monitors WNV prevalence in the mosquito population through mosquito traps that expel carbon dioxide. Mosquitos are drawn to carbon dioxide - the same compound exhaled by the people and animals that mosquitoes feed upon.

As such, the district works through 300 pounds of dry ice in the traps every two weeks, Albright said.

Collecting between 300 to 500 mosquitoes in the traps, they are then gassed to unconsciousness and separated by species before being sent for laboratory testing.

Every year since its arrival in Shasta County in 2004, the West Nile Virus transmission rate has peaked during the months of July and August when the <I>Culex spp</I>. mosquitoes that spread the disease are at their peak populations, Albright previously said.

In 2006, there were four reported human cases including one fatality in Shasta County. The most effective ways to protect the public from WNV are organized mosquito control programs and personal efforts made by the public to reduce their exposure to mosquitoes, according to district literature.

The district has been monitoring the spread of WNV since well before its arrival in Shasta County. It joined with numerous other affected local agencies in the Shasta County West Nile Virus Task Force to provide an organized countywide response to threats of the disease.

Since the arrival of WNV to Shasta county, the District has stepped up its surveillance efforts, adult mosquito control and public information efforts to minimize the potential of transmission of WNV to people and animals living within the district, district documents state. West Nile virus is transmitted through the bites of mosquitoes that have fed on infected birds. It spreads over long distances by the annual migrations of birds. Effective vaccines for WNV are available to provide horses with immunity to the disease. However, no vaccines are currently available to protect humans from WNV.

To report a dead bird - usually a crow or magpie - that may be contaminated with WNV, contact the district at 365-3768.