[Etiological study on viral diarrhea among children in Lanzhou, Gansu, from July 2004 through June 2005].

OBJECTIVE: To study molecular epidemiology of four major etiological viruses among children with acute diarrhea in Lanzhou, Gansu province.

METHODS: Stool specimens were collected from all 400 inpatients less than 5 years old with acute diarrhea admitted in Department of Pediatrics, the First Hospital, Lanzhou University from Jul. 2004 through Jun. 2005. Dako IDEIA kits were used for detection of rotavirus, adenovirus and astrovirus. Calicivirus detection was done by both reverse transcription-polymerase chain reactions (RT-PCR) and ELISA. Further strain characterization of rotavirus and astrovirus was carried out with RT-PCR.

RESULTS: A total of 400 stool samples were collected and tested. Rotavirus was present in 47.3% of the cases: calicivirus in 15.5%, astrovirus in 9.5% and adenoviruses in 7.5%. Mixed infections with multiple enteric viruses were present in 13.5% of all samples. Among 189 rotavirus positive samples, serotype G2 (34.4%) was the predominant strain followed by G3 (32.8%), G1 (1.1%) and mixed-G infection (5.8%). 25.9% of strains remained to be non-typeable. P genotyping showed P [4] (45%) was most common followed by P [8] (22.1%), and non-typeable (32.9%). Strain P [4] G2 (43.6%) was the most common combination followed by P [8] G3 (25.6%), P [4] G3 (13.8%), and P [8] G2, P [4] G1 and P [8] G1. Among 38 astrovirus strains, serotypes 1 (57.8%) was the predominant. Serotype 3 and 8 were found only in one case respectively, 14 strains remained to be non-typeable. A peak admission of rotavirus diarrhea was observed from October through December. More than 95.0% of viral diarrhea patients under hospitalization occurred among children younger than 2 years. The incidence rates of rotavirus were highest in infants aged 6 - 23 months.

CONCLUSION: Rotavirus was the most important pathogen for viral diarrhea among children hospitalized in Lanzhou followed by calicivirus, astrovirus, and adenovirus. The predominant rotavirus strain circulated was P [4] G2, which was different from the finding in the previous years. The high rate of mixed infection with different viral agents was notable.