It's becoming a dark new rite of spring: As green leaves appear, so do the corpses of birds struck down by the West Nile virus. Fear of contracting the virus is also keeping some people from enjoying warm weather.
But locking yourself inside is not the only way to protect yourself from the West Nile virus. You can venture outside with fewer misgivings if you only arm yourself with information and take sensible precautions. The key, of course, is to avoid mosquito bites.
Since it hit North America in 1999, the West Nile virus has worked its way along the east coast from New England to Florida, and westward to Washington and California, causing alarm in communities each time it surfaces. By the end of 2002, 44 states and the District of Columbia had reported verified cases of West Nile virus in animals, mosquitos, or humans. Canada reported West Nile virus in five provinces in 2002. In 2003, the Centers for Disease Control (CDC) had reported verified avian, animal, or mosquito West Nile Virus infections in Florida, Georgia, Louisiana, North Carolina, Michigan, and Minnesota by mid-May. The presence of West Nile Virus was also verified in a dead crow in Ontario in April 2003. The disease has been present for years in Africa, Asia, Europe, the Middle East, and Oceania; scientists still don't know how it crossed the oceans and reached the United States.
According to the CDC, the virus has been found in over 110 bird species as well as in horses and, more rarely, in cats, bats, chipmunks, skunks, squirrels, domestic rabbits, and raccoons. The CDC reports that from 1999 through 2002, there were 241 West Nile virus-caused human deaths in the United States. The most serious manifestation of infection is a fatal encephalitis (inflammation of the brain) that can occur in humans, horses, crows, and certain other domestic and wild birds.
Transmission
The CDC has documented that the West Nile virus can be transmitted through the bite of an infected mosquito. However, as is true with most diseases, exposure to the disease will not necessarily make you seriously ill. Most people will not experience any symptoms; some may experience flu-like symptoms for a few days; and CDC estimates indicate that "less than 1% of people who get bitten and become infected will get severely ill." Those at greatest risk of contracting fatal encephalitis are people over the age of 50.
In Asia and Africa, West Nile virus has also been found in ticks, but they haven't been shown to transmit the disease. There is no evidence that a person can get the virus from simply touching an infected human or animal. However, anyone handling sick or dead animals should use gloves or double plastic bags as a precaution.
Dogs and Cats
The virus has been found in several dogs and cats in the United States.
Like humans, dogs and cats contract the virus via mosquito bites and
cannot transmit it directly to either animals or humans. They do not necessarily die from the virus, and there is no reason to euthanize a dog
or cat who contracts it.
Horses
In 2002, 99.9 percent of all nonhuman mammal cases of West Nile virus occurred in horses. The other cases occurred in dogs and squirrels. Like other mammals, humans, and birds, horses are infected by bites from mosquitos carrying the virus. There has been no evidence of transmission of the disease directly from horses to humans or to other horses. The most common sign of West Nile infection in the horse is weakness. Fever, depression, and fearfulness may also be seen. The infection can be fatal in some cases. There is a vaccine available for horses.
Prevention
The only fully licensed vaccine available is for horses. None yet exists for humans or companion animals. The most effective way to protect yourself, your pets, and your livestock is to prevent mosquito bites. The CDC and the U.S. Department of Agriculture offer some tips:
Ensure the integrity of insect screens around your home, porches, patios, etc.
Don't go outside in the early evening or at dawn or dusk.
If you are outdoors during those times, wear long-sleeved shirts and long pants. But bear in mind that mosquitoes can bite through thin cloth.
Consider using insect repellent (the CDC recommends using one with permethrin or DEET) on your skin and clothing, particularly if you live in a wet, low-lying area where mosquitoes might breed. But use insect sprays sparingly and cautiously. (This means never spraying repellents on children under the age of three or on the hands of children who might put them in their mouths.)
Get rid of standing water around your house—mosquitoes might breed there.
Dispose of any unused outside water containers and drill holes in the bottom of containers that are left outdoors. Turn over plastic wading pools or wheelbarrows when not in use, and do not allow water to stagnate in birdbaths.
Clean clogged roof gutters regularly.
Ventilate ornamental pools or stock them with fish.
Clean and chlorinate swimming pools that are not in use.
If you have livestock, thoroughly clean their troughs every month.
Don't rely on ultrasonic mosquito-repelling machines or vitamin B to ward off bites.
