Enterovirus surveillance--United States, 2000-2001.

Enteroviruses are common viruses associated with diverse clinical manifestations ranging from mild febrile illness to severe and potentially fatal syndromes including aseptic meningitis, encephalitis, neonatal systemic enteroviral disease, and paralytic poliomyelitis. A total of 64 enterovirus serotypes are recognized, including 61 nonpolio enteroviruses. Individual serotypes have different temporal patterns of circulation and often are associated with different clinical manifestations. This report describes temporal trends in reported enterovirus infections in the United States during 2000-2001, including widespread activity of two serotypes (echoviruses 13 and 18) that previously were detected rarely. Monitoring of circulating enterovirus serotypes helped identify these two agents as the primary causes of aseptic meningitis outbreaks in the United States in 2001. Further improvements in timeliness of reporting and geographic representation of the system are needed to allow more complete surveillance for enteroviruses.