West Nile virus is a virus of the family Flaviviridae, found in both tropical and temperate regions. It mainly infects birds, but is known to infect humans, horses, cats, bats, chipmunks, skunks, squirrels, and domestic rabbits. The main route of human infection is through the bite of an infected mosquito.
History
West Nile virus was first isolated from a feverish adult woman in the West Nile District of Uganda in 1937. The ecology was characterized in Egypt in the 1950s. The virus became recognized as a cause of severe human meningoencephalitis in elderly patients during an outbreak in Israel in 1957. The disease was first noted in horses in Egypt and France in the early 1960s.
The first appearance of West Nile virus in North America, in 1999, with encephalitis reported in humans and horses, and the subsequent spread in the United States, may be an important milestone in the evolving history of this virus.
The US outbreak began in the New York City area, and the virus is believed to have entered via an air traveler. Since the first North American cases in 1999, the virus has been reported throughout the United States and Canada east of the Rocky Mountains. There have been human cases and horse cases, and many birds — especially crows and other corvids — are infected. Corvids die of the disease more often than other species of birds so the presence of dead crows is an early indicator of the arrival of the virus.
The Virus: Its Effects and How it is Transmitted
The West Nile Virus is primarily a disease of birds. It is commonly found in Africa, West Asia, and the Middle East, but has also caused outbreaks in Europe. In humans, it can cause encephalitis, an infection of the brain....................
