Molecular Epidemiology of Group A Rotavirus Causing Acute Diarrhea in Infants and Young Children in Rio de Janeiro, Brazil, 1997-1998.

During April, 1997, and February, 1998, an epidemiological survey of group A rotavirus strains causing acute diarrhea in infants and young children was conducted in Hospital Municipal Jesus (Rio de Janeiro, D.C.) Rotaviruses were detected in 18.6% of examined specimens. Among the rotavirus strains tested for dsRNA by PAGE, 70% belonged to the long pattern and 30% the short pattern. A long pattern classified as LD was the most common electropherotype among all of the types. This same pattern had been identified in the city 15 years ago. The most common short pattern was SA type and a few were SB types. The SB types were more common than SA types 15 years ago. Rotavirus infection was observed throughout the period studied, but peaks of infection occurred in May, June, and September. The long pattern was recorded continuously and in all ages studied (0-8 years old), but the short pattern ocurred only in young children (age range 0-11 months) and only in May and June of 1997. This data show epidemiologic differences in infection associated with long and short electropherotypes; the long electropherotypes appear to circulate continuously in the community, whereas the short electropherotype strains appear only in young children in an episodic fashion.