4.13.2001 00:18
Focus of West Nile fight: Prevention
According to new federal guidelines, spraying against the virus will be done only if experts determine that the public is at substantial risk.
BY FELICE J. FREYER
Journal Medical Writer
Rhode Island has begun gearing up for the springtime reemergence of the mosquito-borne West Nile virus and in accordance with new federal guidelines, spraying will be avoided this year except when a team of experts identifies a threat to human health.
In information sessions for municipal leaders yesterday, state officials reviewed the new protocols, which put greater emphasis on prevention through public education, killing of mosquitoes in the larval stage, and more intensive trapping of mosquitoes.
Information gathered last year, when the virus spread from its initial berth in New York City to 12 other East Coast states, shows that the death of crows and other birds from West Nile does not signal that humans are also at risk.
Last year, spraying was ordered for a two-mile radius of each spot where a bird killed by West Nile was found. Birds, particularly crows, blue jays and hawks, are highly susceptible to the virus, but many species of mosquitoes that bite birds don't bite people. And tests on more than 10,000 mosquitoes did not find the virus in a single one.
"Birds are so sensitive that they die at levels of exposure that are way below anything that represents a legitimate human health threat," Malcolm Grant, associate director of the state Department of Environmental Management, told representatives of two dozen municipalities who gathered at the Health Department for the first of two briefings yesterday.
This year, a dead bird will prompt stepped-up trapping of mosquitoes to see if the virus can be found in a human-biting species.
Spraying will take place only when a team of mosquito-control experts determines that the public is at substantial risk of being bitten by infected mosquitoes. Determining that risk, Grant explained, will involve weighing many variables, including whether other mammals have become ill, whether many infected mosquitoes have been found and whether those mosquitoes are in a densely populated area.
Even then, the state team will merely be making a recommendation to the municipalities, and providing the supplies, Grant said. Municipalities can reject the advice and decline to spray. But the state will not provide insecticide to municipalities if it doesn't think spraying is warranted.
"There's a double-check in place," Grant said.
Asked why the state is trying to avoid spraying when it has always maintained that the chemicals were safe, Grant said that spraying is now seen as a waste. "It was not protecting human health," he said. The DEM has always acknowledged that the spraying can cause breathing difficulties in people with lung disease and can kill desirable species of insects.
"We did what we thought was appropriate to protect public health," Grant said. "We've learned something, and we've moved on."
Westerly, which recorded 41 birds killed by West Nile, saw the most spraying last year. Newport and North Kingstown also had higher concentrations, but spraying took place as far north as North Smithfield.
The most important aspect of the anti-West Nile effort, Grant told the municipal officials, will be public education to encourage people to eliminate the stagnant pools where mosquitoes breed. If warranted, cities and towns may take action to enforce the building codes that require people to clean up old tires and garbage-can lids and such that collect water -- and pose a public-health risk.
Starting late next month, the state will set up a phone number for people to call if they see a dead bird that is a member of one of the susceptible species and whose death cannot be explained by other causes.
Additionally, as happened last year, the state will provide cities and towns with larvicide to distribute in catch basins and other wet areas, starting next month. The chemicals prevent mosquito larvae from developing into adults but don't harm other animals.
In vulnerable people, West Nile virus causes an inflammation of the brain that is fatal about 15 percent of the time. It first appeared on this continent in 1999.
Although four people in Rhode Island were tested for West Nile last year, none was infected with it. But some 18 people in New York and New Jersey did become seriously ill and 1 died.
Rhode Island recorded 88 bird deaths from West Nile, and 1 horse died in South Kingstown. Nationwide, some 65 horses came down with West Nile last year.
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According to new federal guidelines, spraying against the virus will be done only if experts determine that the public is at substantial risk.