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. The four most common mosquito-borne brain inflammations in the United States and Canada were the California encephalitis serogroup (CAL), St. Louis equine encephalitis (SLE), western equine encephalitis (WEE), and eastern equine encephalitis (EEE). The majority of the CAL encephalitis cases are caused by one of its members, the La Crosse virus” (Barrett, 2004).
Symptoms
The majority of infected humans show no symptoms or only mild flu-like symptoms. Arboviruses can cause fever, headache, body aches, skin rash and swollen lymph glands. Severe infection may result in coma, tremors, convulsion, paralysis, encephalitis, and occasionally permanent neurologic sequelae or death.
Encephalitis is an acute inflammatory process that affects brain tissue. The meninges, the membranes that cover the brain are also inflamed, giving rise to another type of brain inflammation: meningo-encephalitis. No vaccines are currently commercially available for arboviral diseases. Treatment is limited to relieving the symptoms of the infection and dealing with complications such as brain swelling and difficulty in breathing
Transmission and susceptibility
The virus is mostly maintained in birds (in the Western hemisphere, particularly the American Robin). Female mosquitoes, mainly of the species Culex pipiens, Culex restuan, and Culex quinquefasciatus, bite infected birds, carry the virus in their salivary glands, and infect other birds when they bite again.
Culex pipiens is thought to be the main mosquito species which transmits the virus from birds to mammals. In mammals the virus does not multiply as readily, and it is believed that mosquitoes biting infected mammals do not further transmit the virus..................
