With the mosquito season under way and West Nile virus once again a concern, King County residents are asked to contact Seattle-King County Public Health with reports of dead birds.

Crows in particular die quickly from West Nile virus, and clusters of dead crows may indicate that West Nile virus is present in the community, according to the agency.

West Nile virus was not found in the county in 2007, though in past years birds and horses in the county have died from the virus, which is spread through the bite of an infected mosquito.

The infection can be asymptomatic, or can cause symptoms ranging from mild to severe, including diseases of the brain and spinal column.

In the United States in 2007, 3,630 cases of human West Nile virus were reported in 44 states, and 124 people died, county health officials say. People of all ages can get the disease, but people over 50 are more likely to become seriously ill.

Beginning this week, some of the dead birds reported to the public health agency will be collected for laboratory testing for West Nile virus, along with batches of mosquitoes trapped at locations throughout the county for surveillance purposes.

The best form of protection against mosquitoes is prevention — eliminate their breeding habitat.

The northern house mosquito is the type most likely to infect the county residents with West Nile virus. It prefers to lay eggs in small amounts of standing water, common around most houses. Removing this habitat will reduce the number of mosquitoes near homes.

A mosquito becomes infected by biting an infected bird that carries the virus. Horses are susceptible to West Nile virus infection, which can result in severe disease or death; horse owners should contact their veterinarian because a vaccine is available for horses. West Nile virus is not spread by person-to-person contact, nor is it transmitted directly from birds or other animals to people. Mosquito season, when West Nile virus is of most concern, runs from spring through late fall.

Learn more by calling the West Nile virus hotline at (206) 205-3883 or visit www.metrokc.gov/health/westnile.

Report a dead bird to (206) 205-4394 or www.metrokc.gov/health/westnile/deadbird.htm.

Mosquito problems may also be reported to the public health agency at (206) 205-4394.

More information can be found at the State Department of Health Web site: www.doh.wa.gov/ehp/ts/Zoo/WNV/WNV.html.