RESUMEN
<p><b>OBJECTIVE</b>To study the epidemiology and strain variations of astrovirus infection among children under 5 years of age, hospitalized for acute diarrhea in China.</p><p><b>METHODS</b>Inpatients under 5 years of age with acute diarrhea in hospitals of seven provinces between 1998 and 2005 were enrolled in the study Stool specimens were collected and tested for astrovirus using the Dako Amplified IDEIA Astrovirus kits or reverse-transcription polymerase chain reaction (RT-PCR). Genetic identities of the strains were determined using RT-PCR with serotype-specific primers and confirmed by sequencing of the RT-PCR products.</p><p><b>RESULTS</b>A total of 1668 diarrheal stool samples tested for both rotavirus and calicivirus negative were examined. The detection rate of astrovirus infection was 5.5% (91/1668) and the diarrhea cases caused by astrovirus infection could be found in any season of the year but mainly occurred in cold season from October to next January. Astrovirus detection-rates were: 7.4% among infants aged 9-11 months followed by 6.1% in 12-17 month-olds, and 6-8 months 5.6% & 0-2 months 5.6% before 8 months. Over 95% of astrovirus infections occurred in children before 2 years of age. Among 49 strains, typed, serotype 1(45/91) was most commonly seen while serotype 5 was in two cases and serotype 3 and 8 were detected in only one case respectively.</p><p><b>CONCLUSION</b>Astrovirus seemed an important etiologic agent in young children with acute diarrhea in China and Serotype 1 was the most prevalent one.</p>