Q. I am concerned about West Nile virus. What can I do to help prevent my family from becoming infected?
A. West Nile virus was first identified in 1937 in Uganda. It was first discovered in the United States in 1999 in New York, and has spread rapidly throughout the country.
The West Nile virus is transferred back and forth between mosquitoes and birds. Although many bird species can carry the virus, it is particularly virulent in crows and jays. The virus is spread when a particular species of mosquito bites an infected bird and then bites a person.
Mosquitoes carry the highest amounts of virus in late summer and early fall. For some reason the mosquito that transmits West Nile is more prevalent in dry years.
Although many people are bitten by mosquitoes that carry West Nile virus, few people develop severe disease. Children and adults younger than 50 usually get just a mild flu-like illness or may have no symptoms at all. People older than 50 and those with weakened immune systems are most at risk for severe illness. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. Up to 20 percent of the people who become infected have symptoms such as fever, headache, bodyaches, nausea, vomiting and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms can last for as short as a few days, though even healthy people have become sick for several weeks. The virus is not spread through casual contact such as touching or kissing a person with the virus.
The best way to avoid illness is simply to stay indoors at dusk or dawn, and avoid damp shady areas where mosquitoes are found. Wear long sleeves and pants and use insect repellent when outdoors at high risk times and locations. Make sure you are using EPA-registered repellents. Vitamin B, bug zappers, and ultrasonic devices are not effective in preventing mosquito bites. Mosquito-repellent plants containing citronella are not effective.
People can also help by reducing mosquito breeding sites. At least once or twice a week, empty water from flower pots, pet food and water dishes, birdbaths, swimming pool covers, buckets, barrels and cans. Check for clogged rain gutters and clean them out. Remove discarded tires and other items that could collect water.
Sometimes municipalities will spray areas where West Nile mosquitoes are found. Usually products containing permethrin are used to mist neighborhoods and kill adult mosquitoes.
Some residents are concerned about pesticides. In this case one has to weigh the risk of using pesticides against the threat of severe illness. People should stay indoors with windows closed and A/C units off during the spraying.
Permethrin-based products such as pellets and foggers are also available for homeowner use in landscapes.
Keep in mind that control with these products is at best temporary.