What is the natural history of West Nile virus infection?
According to Field’s Virology West Nile virus is hyperendemic in the Nile delta with a seropositive prevalence of over 60%. Similar levels were once found elsewhere in Egypt but it appears a mosquito eradication program has greatly reduced its prevalence. The clinical course of the disease involves an incubation period of 1-6 days. Symptoms include fever, headache, backache, generalized myalgia and anorexia. Fever may recur. In about half the symptomatic cases a rash appears and there is generalized lymphadenopathy. The illness runs its course in 3 to 6 days with rapid recovery and no permanent effects. In children the disease appears to be milder than in adults. It is thought that most infections are non- or slightly- symptomatic. However, in a small fraction of cases aseptic meningitis or meningo encephalitis occurs. Deaths from West Nile virus associated encephalitis in the US seems to have been confined to the elderly. New York City Experience: In New York a general population “ser
