Maine is one of just nine states that have reported no cases of West Nile virus in humans. But with the dramatic increase in the number of infected birds here over the past two years, state officials say it’s just a matter of time.

“It would not surprise me at all if we had a human case of West Nile virus this year,” said Dr. Dora Mills, director of the state’s Bureau of Health. “It’s been found statewide in birds. We can assume it will eventually be transmitted to people.”

To date, more than 4,100 human cases of West Nile virus have been confirmed nationwide, and 284 deaths reported. There is no known effective treatment.

So far in Maine, West Nile has been found only in birds, but that incidence is growing. In 2001, the state started testing dead birds for the virus. Out of 500 tested, just seven were positive. In 2002, 554 birds were tested, and 65 were infected.

Most of these were in Cumberland County (37), with others identified in Androscoggin (10), Penobscot (7), York (6), Waldo (2), and Hancock, Lincoln and Somerset (1 each).

West Nile lives in adult and larval mosquitoes, wintering over in the insects’ eggs. It infects birds easily, transmitted by the mosquitoes that feed on those birds. Non-carrier mosquitoes that feed on an infected bird may become carriers of the virus, enlarging the population of mosquitoes capable of spreading the disease.

When a carrier mosquito bites a person, that individual also may become infected. While some people experience no symptoms, others develop flulike complaints including fever, aching muscles and headache.

In the worst cases, the virus causes encephalitis, or inflammation of the brain. Symptoms can include very high fever, severe headache, blurred vision, neck stiffness, delirium, coma and death. Diagnosis is confirmed through analysis of blood and spinal fluid.

West Nile disease came on the scene in the United States in 1999 when 62 human cases were diagnosed in the New York City area. Before that, the disease was common in animals and humans in Africa, parts of Asia and the Middle East, but unknown in the western hemisphere.

As part of a four-point public health response, the state will be testing birds again this summer. Beginning in the middle of June, Maine residents are asked to report any dead crows, ravens or blue jays they find. While more than 300 bird species are known to be susceptible, Mills said, those three common, relatively large birds are easy to see and identify.

Mosquitoes in selected locations – mostly in southern coastal areas – will be tested in an effort to identify the most dangerous parts of the state.

The Bureau of Health will ask physicians across Maine to watch for West Nile and to report suspected cases for testing.

Most important, Mills said, is public education. Since the state has no intention of spraying pesticides to kill mosquitoes, it comes down to individual measures to avoid being bitten, she said. They include:

. Staying indoors at times when mosquitoes are especially active.

. Wearing long sleeved shirts and long pants.

. Applying insect repellent as needed, using a product containing the chemical DEET. Mills emphasized that various strengths of DEET are available. Milder concentrations should be used on young children. Children under age 2 should not use DEET at all. Mills recommends citronella as an alternative.

People over 50 years old are most likely to become severely ill from the virus and should be extra vigilant.

Robert Batteese, director of the Maine Board of Pesticides Control, said some states allow aerial spraying of pesticides for mosquito control. Others use water-based chemicals to kill mosquito larvae.

Neither process has long-term benefit, Batteese said, and Maine’s tough environmental laws and a “strong environmental ethic” among residents make it unlikely that either the state or individual towns or cities will undertake such measures unless a public health emergency is declared.

To report dead crows, ravens or blue jays after June 15, call 1-888-697-5846.

For more information on West Nile virus, go to the Bureau of Health Website and follow the links: www.maine.gov/dhs/boh.