- uploaded: Jul 18, 2012
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10. WEST NILE DISEASE
Studies of phylogenetic lineages determined WNV emerged as a distinct virus around 1000 years ago. WNV is a virus of the family Flaviviridae. Part of the Japanese encephalitis (JE) antigenic complex of viruses, it is found in both tropical and temperate regions. It mainly infects birds, but is known to infect humans, horses, dogs, cats, bats, chipmunks, skunks, squirrels, domestic rabbits, crows, robins, crocodiles and alligators. The main route of human infection is through the bite of an infected mosquito. Approximately 80% of West Nile virus infections in humans are without any symptoms.
The virus is transmitted through mosquito vectors, which bite and infect birds.
Direct human-to-human transmission initially was believed to be caused only by occupational exposure, or conjunctival exposure to infected blood. The US outbreak revealed novel transmission methods, through blood transfusion, organ transplant, intrauterine exposure, and breast feeding.