West Nile is a variant of encephalitis closely related to the St. Louis encephalitis virus. Spread through mosquito bites, the virus has been seen thus far in birds, horses and humans. Transmission of the virus does not occur via any means other than mosquito-host.

The virus is named for the region of its initial detection, the West Nile region, and is most commonly found in Africa, the Middle East, and southwestern Asia. The virus has been isolated in numerous areas, including Australia and parts of Europe, but save for sporadic outbreaks is rarely seen in humans.

Outbreaks in humans do occur, however, and can be severe when they do. West Nile generally produces undetectable-to-mild symptoms in humans, and most who are infected never become ill. Those who are elderly, young, or have compromised immune systems are most commonly the ones who become sick, with symptoms including acute fever, rash, headache, joint pain, and occasionally symptoms characteristic of encephalitis or menengitis. Coma and death can result, with fatality occuring in about 17 percent of all cases.

Human outbreaks have been seen in multiple places, including:

1950-57; 2000 -- lsrael

1962 -- southern France

1974 -- central South Africa

1996 -- southeastern Romania

1998-present -- Northeastern United States

Treatment is not sought in most cases, as often those infected are either not aware of any symptoms or experience symptoms mild enough to be easily confused with common flu. ln these cases, the virus runs its course and resolves itself.
ln other cases, supportive measures are the ones most commonly taken, as West Nile has no cure. The patioents are kept hydrated and attempts are made to reduce fever. Treatment with ribavirin, an antiviral drug, can be helpful within the first few days of infection.

As there is no cure, prevention is obviously the best policy. ln areas of known outbreak, wild bird species -- particularly crows, as they are highly subceptible -- are monitored to assist in the tracking of the virus. Birds found dead are examined for signs of the virus, and spraying of pesticide and other mosquito-abatement measures are taken in areas where infected birds are found.

Other precautions against infection where West Nile Virus is known to be present include:

Avoiding areas where mosquitos live at dusk and at dawn (their peak feeding/biting times);

Wearing longsleeved shirts and long pants when going outdoors for extended periods;

Using insect repellents;

Dumping or draining areas of standing water (mosquito breeding grounds);

lnstalling screens on the windows of your home

While West Nile is not a serious threat to most humans at this time, it can cause severe epidemics, and an attitude of caution is warranted. lf the virus is reported to be in your area, take steps to protect yourself from it, and pay attention to local news regarding movement of the virus. Though currently your location may not be threatened by it, the increace of air travel has made the spread of disease a far quicker proposition, and thanks to an airliner harbouring a mosquito on a trans-oceanic flight or an ill traveller unwittingly carrying the disease to a new location, this virus may soon be coming to an insect near you.