Three dead birds found in the Reno area have tested positive for the West Nile virus, health officials said Monday.
Scott Monsen of the Washoe County Health Department said the birds were found over the weekend in the Toll Road area, Galena-St. James area and the Lazy 5 Park area in Spanish Springs.
Monsen said the county plans to start spraying this week to kill mosquitos, which carry the virus, and will trap and test mosquitos to ensure the spraying is working.
The state Agriculture Department on Monday released test results for samples collected last week in Humboldt, Washoe and Clark counties, and confirmed the presence of the virus in Humboldt.
The agency said three horses have tested positive for the virus, including one in Churchill County that was destroyed after it became severely ill. Dr. David Thain, state veterinarian, said the 5-year-old stallion had not been vaccinated against the mosquito-borne disease.
Officials began urging horse owners last year to vaccinate their animals when the likelihood of the disease arriving in Nevada seemed evident. Mules and donkeys also should be vaccinated.
Experts say about 30 percent of horses infected with the disease die. But Thain said the vaccine is 95 percent effective. Vaccinated animals must get an annual booster shot.
Tests conducted on dead crows found in Carson City and Lyon County and on mosquitoes trapped in Lyon, Mineral and White Pine counties confirmed the disease's presence in all of those areas last week.
So far, two human cases have been reported in Nevada - one in Reno and in Las Vegas.
Health officials are reminding people to take preventive measures to avoid being bitten by mosquitos. That includes use of insect repellent, wearing long sleeves and pants, making sure house screens fit properly and draining any standing water around homes where mosquitos might breed.
On the Net:
Washoe District Health Department: www.co.washoe.nv.us/health
Nevada Department of Agriculture: www.agri.state.nv.us
National Centers for Disease Control and Prevention: www.cdc.gov