OUTBREAKS OF ASTROVIRUS GASTROENTERITIS IN DAY-CARE-CENTERS

Objective: This study evaluated astrovirus as a cause of diarrhea outb reaks among infants and toddlers in day care centers. Design: Stool sp ecimens were collected weekly during four periods (from January 1986 t hrough December 1991) from children 6 to 30 months of age who were enr olled in prospective studies of diarrhea in day care centers. All diar rheal stool specimens were tested for bacterial enteropathogens, rotav irus, enteric adenovirus, and Giardia lamblia. A total of 1365 stool s pecimens from 70 outbreaks in which no etiologic agent was identified and from another 11 outbreaks with a known cause were tested for astro virus, by means of a monoclonal antibody-based enzyme immunoassay. Con firmatory testing was performed by reverse transcriptase-polymerase ch ain reaction with primers designed to produce an 89 base-pair product. Results- Astrovirus was detected in 6 (7%) of the 81 outbreaks. Of 21 7 children tested, 73 (34%) were infected with astrovirus; infections in 35 (48%) were symptomatic and in 38 (52%) asymptomatic. The six out breaks lasted 11 to 44 days (median 22 days). Astrovirus excretion was detected for a duration of 2 to 30 days, with excretion occurring fro m 1 to 8 days (median 2 days) before diarrhea began to 1 to 20 days (m edian 2 days) after diarrhea ceased. Younger children (less-than-or-eq ual-to 12 months) were at greater risk than older children (p = 0.011) of becoming infected with astrovirus during an outbreak and were more likely (p = 0.015) to have symptoms when infected. Of 24 specimens wi th astrovirus by enzyme immunoassay, 20 (83%) were confirmed to have t he virus by reverse transcriptase-polymerase chain reaction. Conclusio n: Astrovirus was an important cause of outbreaks of diarrhea among ch ildren attending day care centers, more frequently infected younger ch ildren, and often produced asymptomatic infections.