Rotavirus infection in Brazil: epidemiology and challenges for its control

Abstract

Worldwide, rotaviruses account for 600,000 to 870,000 deaths per year among infants and young children. In Brazil, rotaviruses were first seen in 1976 by scanning electron microscopy of stool samples from diarrheic infants in Belém, Pará. Hospital-based studies have shown that rotaviruses are associated with 12-42% of cases of acute diarrhea. In addition, community-based studies yielded an average of 0.25 rotavirus-related diarrheal episodes per child per year. G types 1 to 4 account for about two-thirds of circulating strains, but the (unusual) P[8],G5 genotype has been claimed to cause over 10% of rotavirus diarrheal episodes. It has been shown that over 70% of children develop rotavirus antibodies by the age of 4-5 years. The tetravalent rhesus-human rotavirus vaccine (RRV-TV) conferred 35% protection according to a two-year follow-up study in Belém, Pará, Brazil, but reached an efficacy of 60% during the first year of life. RRV-TV was also shown to be 75% protective against very severe gastroenteritis in northern Brazil. Vaccination with RRV-TV has been suspended recently in the United States because of the detection of intussusception as a side effect. Therefore, further vaccine trials in Brazil will probably involve rotavirus candidate vaccines other than RRV-TV.