Recent studies have associated human Metapneumovirus (HMPV) infection in children with respiratory disease of similar severity as respiratory syncytial virus (RSV) infection. We studied 668 banked swab specimens (one per admission) collected from a population-based, prospective study of acute respiratory illness among inpatient children from two U.S. cities. Specimens were tested for HMPV, RSV, influenza, and parainfluenza viruses by reverse transcription–polymerase chain reaction assays. Twenty-six (3.9%) were positive for HMPV; 125 (18.7%) for RSV; 45 (6.7%) for parainfluenza 1, 2, or 3; and 23 (3.4%) for influenza. HMPV-positive children were significantly older than RSV-positive children. HMPV-positive children required medical intensive care and received supplemental oxygen in similar frequencies to RSV-positive children. Among children hospitalized with respiratory illness, the incidence of HMPV infection was less than RSV, but clinical disease severity mirrored that of RSV infection. Further investigations to better characterize HMPV infection and its clinical effect are needed.

Onset weeks and durations of RSV seasons vary substantially by year and location. Local RSV data are needed to accurately define the onset and offset of RSV seasons and to refine timing of passive immune prophylaxis therapy recommendations.

We documented transmission by food and person-to-person contact; persistence of virus despite sanitization onboard, including introductions of new strains; and seeding of an outbreak on land.

In 2001, increased activity of the rarely detected enterovirus echovirus type 13 (E13) was observed in the United States. This article describes the epidemiologic, clinical, and genetic characteristics of E13 activity in the United States in 2001, compared with E13 activity abroad in 2000-2002. In the United States, E13 accounted for 376 (24%) of the 1584 enterovirus isolates reported in 2001 (29% of the reported isolates had a known serotype), compared with 74 isolates reported during 1970-2000. Five states reported aseptic meningitis outbreaks associated with E13, for a total of 521 cases. All characterized E13 isolates from the United States, Europe, Asia, and Oceania recovered in 2000-2002 were at least 95% identical to each other in VP1 capsid gene sequence, but they were genetically distinct from E13 isolates recovered before 2000. Continued surveillance of enteroviruses is important to alert physicians and public health officials to changes in disease trends and to improve efficiencies of clinical intervention.