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8.1.2001 00:09
Take precautions, but no cause for panic
What is the significance of finding five mosquitoes with West Nile virus in Foster?
It's too soon to say. Health and environmental officials were not surprised or alarmed by the discovery. They already knew that the virus was present among mosquitoes in Rhode Island, because it has killed at least three birds this year.
Additionally, the virus has been identified this year in mosquitoes trapped in several states, including Connecticut, New York and New Jersey. So it was expected that eventually an infected mosquito would be trapped in Rhode Island.
Because there are millions of mosquitoes, this is merely the first time that state traps have happened to collect mosquitoes that are infected. The five represent two species of mosquitoes, both of which bite mammals.
How is the state responding to this discovery?
By trying to get a clearer picture of West Nile activity in the area. Ten additional traps were to be set in the Foster area last night.
Additionally, the state will intensify its efforts to urge people to protect themselves from mosquitoes.
What can I do to avoid getting West Nile virus?
Take steps to keep mosquito bites to a minimum.
First, don't grow mosquitoes in your yard. Mosquitoes breed in stagnant pools and puddles that last for more than a couple of days. (Fish ponds are OK because the fish will eat the larvae.) Just one cup of standing water can produce thousands of mosquitoes.
Change the water in your birdbath twice a week; clean your rain gutters so water doesn't pool there; don't let puddles form in your swimming-pool cover; and remove any tires, buckets, garbage-can covers and other receptacles where water can gather.
Second, protect yourself when you go out, especially in the evening and early morning when mosquitoes are most active, by applying insecticide containing 30-percent DEET to your skin and clothing, and wearing long-sleeved shirts and long pants.
Third, keep mosquitoes out of your home by keeping your screens in good repair and making sure they sit snugly in their frames.
Now that we know mosquitoes are infected, why isn't the state spraying to kill them?
Because it is not yet known that there is a significant threat to human health, and there is not yet reason to believe that spraying will make a difference.
Last year, cities and towns sprayed pesticide within a two-mile radius of the spot where any bird killed by West Nile was found. But it has since been learned that birds with West Nile do not indicate a higher risk to people. Birds, particularly crows, blue jays and hawks, are much more sensitive to the virus than people are. Also, many breeds of mosquito that bite birds don't bite people.
So this year, according to protocols established by the federal government, spraying will occur only after a team of mosquito experts determines that the public is at substantial risk of being bitten by infected mosquitoes. The team will weigh many variables, including whether other mammals have become ill (that hasn't happened this year), whether many infected mosquitoes have been found, and whether those mosquitoes are in a densely populated area.
Meanwhile, the personal-protection steps described above are the best way for people to avoid West Nile virus.
What happens to a person who is bitten by a West Nile-infected mosquito?
Many people bitten by infected mosquitoes do not get sick at all. Those who do tend to experience mild, flu-like symptoms. Occasionally, the infection can lead to an inflammation of the brain, but that happens primarily in frail, elderly people.
When it bites someone, the mosquito injects the virus into the bloodstream, where it starts multiplying. If the infected person's immune system does not first kill the virus (as often happens), in 3 to 15 days after the mosquito bite, the virus can cross the blood-brain barrier to infect the brain, interfering with nervous-system function and causing inflammation. The person may experience fever, severe headache, eye pain, drowsiness, extreme muscle weakness and enlarged lymph nodes.
A small percentage of people -- usually the elderly or those with weakened immune systems -- become seriously ill, sometimes progressing to tremors, convulsions or death. The death rate is around 3 to 15 percent.
Has anyone in Rhode Island ever gotten sick with West Nile virus?
No. Last year, four people were tested for it, but none had it.
Besides birds and mosquitoes, which animals can get West Nile virus?
Many types of mammals can become infected with West Nile virus, but humans and horses appear to be the only ones that become ill. It's possible that cats and dogs can become infected, too, but there have been few documented cases.
Can I catch West Nile virus from an infected person or horse?
The only way to get West Nile virus to be bitten by an infected mosquito. There is no evidence of person-to-person, animal-to-animal or animal-to-person transmission of the disease. People and horses are considered "dead-end hosts" because the virus doesn't build up in the bloodstream enough to be picked up by another creature, even a mosquito.
Where can I get more information?
The Department of Health's Family Health Information Line: (800) 942-7434.
The Department of Environmental Management's Mosquito Information Line (recorded information): 222-2793.
Web sites: www.state.ri.us/dem and www.healthri.org
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