Epidemiology of rotavirus gastroenteritis in the Amazon region and the need for a specific vaccine

RESUMO

In the Amazon region, rotaviruses account for at least 30 per cent of all episodes of acute gastroenteritis among hospitalized children and are associated with nearly 1O per cent of cases of infantile acute diarrhea at community level. All four rotavirus serotypes are shown to infect children in our region, serotype l being predominant (about 50 per cent). Sequential infections in the same child, caused by different serotypes, are commonly noted. No clear seasonal variation on the occurrence of rotavirus diarrhea has been recorded, as cases are readily detected throughout the year. Rotavirus diarrhea cases have been found to be, in general, more severe than those of other aetiology. On the other hand, it has been noted that early (children less than 4 months of age) rotavirus infections are more likely to be asymptomatic (p = 0.021). Occurrence of rotavirus infections among Amazonian Indian populations seems to be very common. An explosive outbreak of rotavirus diarrhea affected possibly 88 per cent of both children and adults of the Tiryió population, Northern Pará State. In addition, rotavirus antibody was detected in 54.7 per cent of 1,299 sera collected from Amerinds belonging to 13 relatively isolated communities in the Amazon region. In the light of the above mentioned findings it was suggested that our region would be suitable for a field trial with a rotavirus-candidate vaccine. A study is therefore underway aiming to compare safety, immunogenicity and efficacy of a rhesus-human reassortant rotavirus (RRV-tetravalent) vaccine and placebo in 500 healthy infants living in the peripheral area of Belém.