Dr. Paul Effler, state epidemiologist, said 20 birds were collected from the runway area of Kahului Airport this week. He said blood tests conducted at the state laboratory in Pearl City showed one of those birds — a wild sparrow — showed preliminary positive test results for the virus, which is spread by the bite of an infected mosquito.

Effler said samples were sent yesterday to the Centers for Disease Control and Prevention for further testing and it will take seven to 10 days for those results.

He said the initial test can produce false positives in birds as well as humans. That first test measures antibodies that indicate exposure to West Nile virus, but Effler said the test could react positively to other antibodies that are similar to West Nile. "In humans, we know that to be the case," he said.

Although the disease has spread through most of the nation, Hawai'i has seen no cases of the virus and has continued an aggressive prevention program aimed at killing mosquitoes and monitoring for dead birds.

As a precaution, state and county officials last night began intensive mosquito spraying in and around the Kahului Airport. "We need to respond quickly and forcefully to control this potential public health threat to the state, as we wait for confirmatory lab results," Effler said.

Effler said the threat of the disease shows the urgent need for prevention. "Obviously, we're very concerned."

Officials have focused prevention efforts near airports and harbors fearing that infected mosquitoes may enter the Islands on airplanes or cargo containers. Birds are more susceptible to the virus once bitten by an infected mosquito, and officials watch for dead birds as an indication that the virus may have spread.

The CDC yesterday reported a total of 1,657 human cases with 53 deaths this year. California has been hardest hit with 15 deaths.