Acute gastroenteritis cases associated with noroviruses infection in the state of Rio de Janeiro.

In March 2005, the Epidemiological Surveillance Service of Resende, municipality of the Middle Paraiba Valley, State of Rio de Janeiro, reported a sudden spontaneous occurrence of acute gastroenteritis cases in children in a public day care center. Further, between May and June 2005, gastroenteritis outbreaks or sporadic cases of gastroenteritis were reported in two other municipalities, Piraí and Rio Claro, also located in the Middle Paraiba Valley. From March to June 2005, 50 fecal samples were collected in this region and those samples were tested for the presence of bacteria and other parasites and were demonstrated to be negative. Polyacrylamide gel electrophoresis and an enzyme immunoassay were performed for adenovirus and rotavirus detection and reverse transcription-polymerase chain reaction was performed to investigate the presence of norovirus (NoV) and astrovirus. In addition, a quantitative TaqMan real time PCR for NoV was performed for quantification of viral DNA in order to compare the results with those obtained by conventional RT-PCR. NoV was detected in 33 out of 50 (66%) samples, and a 100% correlation between both methodologies was obtained. These results are demonstrating that NoV was the etiological agent responsible for those acute gastroenteritis cases. Partial nucleotide sequence analysis of the capsid gene revealed that the circulating strain was NoV GII/4 confirming the worldwide distribution of this genotype. The results highlight the role of NoV as a main viral agent responsible for gastroenteritis cases in children and adults both in outbreaks as well as in sporadic cases of acute gastroenteritis.