12.31.2000 00:22
R.I. officials mull lessons of West Nile strategy
An evaluation of this year's efforts to prevent human cases of the mosquito-borne disease will influence policies next year.

By FELICE J. FREYER
Journal Medical Writer

"Well, nobody got sick."

That was the first response from Malcolm J. Grant, associate director for natural resources with the state Department of Environmental Management, when he was asked whether the state's effort against West Nile virus this year was successful.

Of course, as Grant readily acknowledges, it's impossible to prove whether the lack of human infections from a mosquito-borne virus new to this area resulted from the prevention efforts or just dumb luck.

But the three-pronged strategy -- testing animals to track the virus, controlling mosquito populations, and educating the public -- succeeded by other measures, too, Grant said.

The issue received extensive media coverage that stressed the importance of personal protection against mosquito bites, and everyone at the state and municipal levels did what they were supposed to do without a hitch.

"I think it went amazingly well," agreed Robert J. Marshall Jr., associate director of the Department of Health, which teamed up with the DEM in the West Nile virus effort. "The key from my point of view [was that] we started with a plan back in January. We adapted the mosquito abatement plan to accommodate this new emerging disease. We knew what we were going to do. . . . We didn't have to make those decisions on the spot."

The virus was detected in 88 dead birds and one horse in Rhode Island. Only mosquitoes can spread West Nile virus, so clearly there were infected mosquitoes, too, but tests of 10,795 mosquitoes in this state didn't find it in a single one.

Although Rhode Islanders escaped unscathed, nationwide this year, 18 people became seriously ill with West Nile infections (residents of New York and New Jersey); one died and one is in a persistent vegetative state, according to the Centers for Disease Control and Prevention. That's an improvement over 1999, the year the virus first appeared on this continent, when 62 people in New York became seriously ill, and 7 died. New York responded with a massive mosquito-spraying program in the fall of that year.

During the intervening winter, the federal Centers for Disease Control and Prevention began planning for the likelihood that the virus would survive the winter and make its way via migratory birds to other regions.

Rhode Island was among 17 states that participated in a program to track and control the virus's progress. Now, officials from those states and the CDC are completing a series of meetings to assess that program and determine what changes are needed.

Based on conversations so far, Grant said, those changes are likely to include:

Less emphasis on spraying pesticides to kill adult mosquitoes.

Last summer and fall, mosquito spraying took place within a two-mile radius of places where infected birds were found. In Rhode Island, 600 gallons of pesticide were sprayed in communities from Westerly to North Smithfield.

But it turns out that, although infected birds are an early sign that the virus has reached a given area, bird infections don't predict the risk to humans, because many of the mosquito species that bite birds don't bite people. So spraying in response to bird infection "is probably overly aggressive," Grant said. Additionally, officials are "very sensitive" to environmentalists' concerns about widespread use of these toxic chemicals, he said.

Less emphasis on testing birds and more emphasis on testing mosquitoes. The goal is to identify the virus in the human-biting mosquito species to alert people to a heightened risk. Despite an extensive mosquito-testing program in Rhode Island, it was a needle-in-a-haystack search that failed. Next year, Grant said, may bring "a more aggressive search of that haystack."

"Last summer we were going in a number of directions, trying to cover all our bases," Grant said. "Now we can focus on one area and back off from another -- which will increase the chances of finding the disease in mosquitoes before we see it in horses or humans."

For unknown reasons, horse infections were not a good predictor of human infections this year, even though the same species of mosquitoes bite both. Horse infections occurred later in the season; the 18 human cases were reported between July 15 and Sept. 9, while the first horse infection wasn't detected until Aug. 12, and horse infections were reported through Oct. 28, according to the CDC. Sixty-five horses nationwide came down with West Nile virus, most in New York and New Jersey.

There's a hazard in Rhode Island's apparent success at preventing West Nile infections: people may conclude that the state overstated the risk and become complacent.

Ken Ayars, chief of the DEM's agricultural division, said that such issues will be factored into planning for each year. And he defended the state's aggressiveness in publicizing the West Nile hazard.

"We were preparing for [2000] based upon only one state's experience -- New York, New York City in particular, which had a horrid experience with it," Ayars said. "It's a very difficult atmosphere, dealing with death and illness. You always want to avoid that type of scenario. . . .

"It's okay for me if we're faulted on trying too hard to get the message out. We wanted to make people aware [that] they have a lot of personal responsibility."

As human illness goes, West Nile virus is hardly the worst scourge on the planet. Many people who get it don't even fall ill; those who do usually recover. Is the money and effort expended on fighting West Nile worth it?

Absolutely, said Marshall, of the Health Department.

"It's important because we can prevent it," he said. "This is a disease that if people take personal precautions -- if we alert them in time -- there's no need for anybody in Rhode Island to get infected with West Nile virus. . . . This is a key message of public health. Our exposure to disease is often directly related to our behavior."

Additionally, Marshall said, there's limited experience with West Nile virus in the United States, and the virus is known to cause outbreaks and deaths in the Middle East. "It's too early for us to conclude what the impact of this will be on our population," Marshall said. "Out of an abundance of caution, we don't want say this is not a problem until we're sure it's not a problem."

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