West Nile Virus - Emerging Infectious Disease

WEST NILE VIRUS

The West Nile virus was first recognized in the 1930s in Africa and first seen in humans the United States in 1999. The 1999 epidemic was distressing as residents of New York City reported to hospitals with initially undiagnosable meningitis. Most human infections are asymptomatic. When symptoms are present, head-ache and fever are most frequently reported. Less than 1% of those infected develop more severe illness, including meningitis (CDC, 2001e).

The incubation period (ie, from mosquito bite to onset of symptoms) is between 5 and 15 days. There is no treatment for West Nile virus infection. Patients are supported by fluid re-placement, airway management, and standard nursing care when meningitis symptoms are present.

Birds are the natural reservoir for the virus and since 1999, the population of infected birds in the eastern United States has in creased steadily. Mosquitoes become infected when feeding on birds and can transmit the virus to animals and humans. Most communities in the eastern United States have developed a pub-lic health surveillance system to estimate the prevalence in birds and mosquitoes. There is no human-to-human transmission of the virus and no evidence of transfer from infected birds to humans. However, as a precaution, it is wise to teach people in affected areas to wear gloves if handling a dead bird (CDC, 2002c).