Department of Internal Medicine, Flushing Hospital Medical Center, Flushing, New York 11355, USA
Address for correspondence: Deborah S. Asnis, M.D., Flushing Hospital Medical Center, 4500 Parsons Boulevard, Flushing, New York 11355. 718-670-3012; fax 718-670-4510.
IDDOC{at}erols.com
Viruses cause most forms of encephalitis. The two main types
responsible for epidemic encephalitis are enteroviruses and
arboviruses. The City of New York reports about 10 cases of
encephalitis yearly. Establishing a diagnosis is often difficult.
In August 1999, a cluster of five patients with fever, confusion,
and weakness were admitted to a community hospital in Flushing,
New York. Flaccid paralysis developed in four of the five patients,
and they required ventilatory support. Three, less severe, cases
presented later in the same month. An investigation was conducted
by the New York City (NYC) and New York State (NYS) health departments
and the national Centers for Disease Control and Prevention
(CDC). The West Nile virus (WNV) was identified as the etiologic
agent. WNV is an arthropod-borne flavivirus, with a geographic
distribution in Africa, the Middle East, and southwestern Asia.
It has also been isolated in Australia and sporadically in Europe
but never in the Americas. The majority of people infected have
no symptoms. Fever, severe myalgias, headache, conjunctivitis,
lymphadenopathy, and a roseolar rash can occur. Rarely, encephalitis
or meningitis is seen. The NYC outbreak resulted in the first
cases of WNV infection in the Western Hemisphere and the first
arboviral infection in NYC since yellow fever in the nineteenth
century. The WNV is now a public health concern in the United
States.
