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A prospective hospital-based sentinel study conducted in Rio de Janeiro identified a shift in the pattern (long to short electropherotype and P(8) to P(4) genotype) of rotavirus strains recovered from children with severe diarrhea a few months after the far-reaching Brazilian rotavirus immunization program was launched, posing new interesting challenges.

A 4½-year hospital-based survey was conducted in Rio de Janeiro to determine baseline rates of gastroenteritis-related cases, hospitalizations, and deaths; to examine the prevalence of rotavirus strains causing admissions; and to assess the immediate impact of the nationwide rotavirus immunization program launched in March 2006. From August 2002 to May 2007, 14,473 (10.4%) of the 139,747 consultations had AGE as primary diagnosis, 491 (3.4%) children required hospitalization and two (0.4%) dehydrated children died. Gastroenteritis contribution to hospitalizations varied from ~2.3% in 2004 and 2006 to 6.4% in 2005, being roughly half of them rotavirus-related cases. A gradual decrease in rotavirus strain diversity was observed from 2002 to 2005 when a single G9P[8] prevailed until April 2006. Then only short profile G9P[4] and G2P[4] strains were detected. Gastroenteritis cases were distributed year-round in a trimodal pattern with major winter peaks. Local climate apparently affected the incidence of gastroenteritis: reduction in dry years (2004 and 2007) and explosive outbreaks caused by multiple agents during the heavy rainfalls and recurrent floods of the 2005-early 2006 period. Besides rotavirus, adenovirus and calicivirus were major gastroenteritis agents of these seemingly waterborne outbreaks. In conclusion, rotavirus vaccination impacted marginally, if at all, on the incidence of childhood gastroenteritis, as favorable results obtained by comparing data from the post-vaccine period to the preceding unusual 2005 year all but disappeared when comparing to previous pre-vaccination periods, and the shift towards G2P[4] rotavirus strains may be a global trend unrelated to vaccination.

Rotaviruses are the main cause of infantile acute diarrhea, and a monovalent (G1P [8]) vaccine against the virus was introduced into the Brazilian National Immunization Program for all infants in March 2006. The objectives of this study were to determine the rate and genotype distribution of rotavirus causing infantile diarrhea in the Triaˆngulo Mineiro region of Brazil during 2011-2012 and to assess the impact of local vaccination. Fecal specimens were analyzed for detection and characterization of rotavirus using polyacrylamide gel electrophoresis, reverse transcription followed by polymerase chain reaction (PCR), and PCR-genotyping assays. Overall, rotavirus was diagnosed in 1.7% (6/348) of cases.