Rotavirus serotypes and electropherotypes identified among hospitalised children in S？o Luís, Maranh？o, Brazil

during june 1997-june 1999 rotavirus infection was screened in infants aged up to 2 years and hospitalised with acute diarrhoea in s？o luís, northeastern brazil. altogether, 128 stool samples were collected from diarrhoeic patients and additional 122 faecal specimens from age- and- temporal matched inpatients without diarrhoea were obtained; rotavirus positivity rates for these groups were 32.0% (41/128) and 9.8% (12/122), respectively (p < 0.001). both electropherotyping and serotyping could be performed in 42 (79.2%) of the 53 rotavirus-positive stool samples. long and short electropherotypes were detected at similar rates - 38.1% and 40.5% of specimens, respectively. overall, a g serotype could be assigned for 35 (83.3%) of specimens, the majority of them (66.7%) bearing g1-serotype specificity. taking both electropherotypes and serotypes together, g1 rotavirus strains displaying long and short rna patterns accounted for 30.9% and 19.0% of tested specimens, respectively; all g2 strains had short electropherotype. rotavirus gastroenteritis was detected year-round and, in 1998, the incidence rates tended to be higher during the second semester than in the first semester: 45.2% and 26.1% (p = 0.13), respectively. rotavirus infections peaked at the second semester of life with frequencies of 30.1% and 13.5% for diarrhoeic children and controls, respectively. while the six rotavirus strains bearing g2-type specificity were circulating throughout the whole study period, g1 serotypes (n = 27) emerged as from june 1998 onwards, 20 (74.1%) of which clustering in 1998. these data underscore the importance of rotaviruses in the aetiology of severe infantile gastroenteritis in northeastern brazil and sustain the concept that a future vaccine should confer protection against more than one serotype.