The West Nile Virus Outbreak of 1999 in New York: The Flushing Hospital Experience

Abstract

West Nile Virus (WNV) is a mosquito-borne flavivirus, which has been known to cause human infection in Africa, the Middle East, and southwestern Asia. It has also been isolated in Australia and sporadically in Europe but never in the Americas. Clinical features include acute fever, severe myalgias, headache, conjunctivitis, lymphadenopathy, and a roseolar rash. Rarely is encephalitis or meningitis seen. During the month of August 1999, a cluster of 5 patients with fever, confusion, and weakness were admitted to the intensive care unit of the same hospital in New York City. Ultimately 4 of the 5 developed flaccid paralysis and required ventilatory support. Three patients with less-severe cases presented shortly thereafter. With the assistance of the New York City and New York State health departments and the Centers for Disease Control and Prevention, these were documented as the first cases of WNV infection on this continent.

West Nile Virus Infection in the Intensive Care Unit: A Case Series and Literature Review

“…The most common and preferred diagnostic test is the immunoglobulin M (IgM) antibody-capture enzymelinked immunosorbant assay (ELISA), which can be performed on serum or CSF. The presence of the antibody in CSF is highly suggestive of a neurological infection (14). Individuals recently vaccinated for, or infected with, other related flaviviruses may have a positive WNV IgM ELISA (2).…”

“…Encephalitis with profound muscle weakness was also prognostically important (8). Mortality may be much higher among patients admitted to the ICU, especially those requiring mechanical ventilation (14). Important morbidity may follow severe WNV infection, including residual weakness and short-term memory loss (14,16).…”

“…Mortality may be much higher among patients admitted to the ICU, especially those requiring mechanical ventilation (14). Important morbidity may follow severe WNV infection, including residual weakness and short-term memory loss (14,16). In a case series of 57 hospitalized WNV patients from Ontario in 2002 (5), 80% of discharged patients had impairment in their functional status from persistent ataxia, weakness and cognitive dysfunction (5).…”

“…In a case series of 57 hospitalized WNV patients from Ontario in 2002 (5), 80% of discharged patients had impairment in their functional status from persistent ataxia, weakness and cognitive dysfunction (5). Recovery can be further delayed in immunocompromised individuals (14) and ICU survivors due to both the primary infection and complications related to prolonged hospital admission.…”

Acute Viral Encephalitis: The Recent Progress.

“…In the summer1999, there was an unexpected outbreak in New York of encephalitis by the West Nile virus, which had not been known to invade the American continent before. During this period, 62 cases of encephalitis in human patients and 25 cases of encephalitis in horses were diagnosed (58,59). It became clear through gene analysis of the prevailing virus that the high neurogenicity new virus occured in the Middle East and invaded NewYork City.…”