West Nile Virus essays

West Nile Virus essays West Nile virus belongs to a group of enveloped RNA viruses called Flavivirus whose members such as Japanese encephalitis virus, St. Louis encephalitis, etc. are transmissible by mosquitoes and have been shown to cause animal and human infection. West Nile virus was first isolated in 1937 from the blood of a woman in the West Nile district of Uganda. West Nile virus is maintained in zoonotic cycles, mainly through the bird-mosquito cycle in wetland ecosystems, and the virus has been isolated from 43 different mosquito species. In certain dry and warm habitats, bird-feeding argasid (soft) or amblyommine (hard) ticks may serve as substitute vectors and form a bird-tick cycle. Migratory birds usually carry the virus, and the virus spreads to man by mosquitoes and ticks. West Nile fever in humans usually is an influenza-like illness. The most frequent clinical manifestations are fever, severe headache, sore throat, backache, myalgia, fatigue, stiffness of the neck, nausea, abdominal pain, diarrhea, rash. In addition, patients with encephalitis often exhibit disturbed consciousness, tremor of extremities, confusion, vomiting, paralysis, etc. The fatality rate was reportedly up to 15.1 percent in acute encephalitis and 1.8 percent in acute meningitis. The time of exposure to the West Nile virus, to the time of onset of symptoms ranges from 3 to 6 days. Most people begin with an abrupt onset of fever lasting from 3 to 5 days. Wild birds are the primary hosts of West Nile virus, although the virus was also isolated from several terrestrial avian species such as ducks and pigeons. The virus has also been isolated from different mammals such as horses, dogs, cattle, camels, mice, hamsters, etc., however these species are less important in maintaining the zoonotic cycles. West Nile virus is endemic in Africa and Eurasia. The first major West Nile fever epidemic in Europe occurred in Romania, in 1996, with ...