National laboratory surveillance of viral agents of gastroenteritis in Brazil

In 1984 an enzyme immunoassay for rotavirus and adenovirus developed in the Virology Department of the Oswaldo Cruz Foundation was distributed to laboratories in 14 Brazilian states as part of a project to survey viral agents in fecal specimens from children with diarrhea. The ensuing surveillance continued for 3 to 5 years, and in 1991 the results obtained by all laboratories that tested 300 or more fecal specimens were reviewed at a workshop held in Belém. These results showed that rotavirus had been detected in 13% to 20% of the specimens tested, with positive specimens appearing to peak in the May to September "winter" or dry season in Brazil's central and southern states but not in the more tropical northern areas. Adenovirus, detected in 0.7% to 5.5% of the specimens tested for it, showed no seasonal variations. Many other viral agents known to cause gastroenteritis (e.g., astrovirus, small round-structured viruses, calcivirus, and group C rotavirus) were detected at centers that used electron microscopy. Picobirnavirus, a novel agent not yet associated with gastroenteritis in humans, was found by polyacrylamide gel electrophoresis in specimens from a number of centers using this technique. Vaccines to prevent rotavirus that are currently under development would be of great use in Brazil, where rotavirus is the most common cause of childhood diarrhea. Improved diagnostics will be required to assess the importance of the other viral agents.