Epidemiologic and genotypic characteristics of rotavirus strains detected in children less than 5 years of age with gastroenteritis treated at 3 pediatric hospitals in Zimbabwe during 2008-2011

BACKGROUND:: In anticipation of rotavirus vaccine introduction, the Zimbabwe Ministry of Health initiated rotavirus surveillance in 2008 to describe the rotavirus epidemiological trends and circulating genotypes among children <5 years of age. METHODS:: Active hospital-based surveillance for diarrhea was conducted at 3 sentinel sites from January 2008 to December 2011. Children aged <5 years, who presented with acute gastroenteritis as a primary illness and who were admitted to a hospital ward or treated at the emergency unit, were enrolled in the surveillance program and had a stool specimen collected and tested for rotavirus by enzyme immunoassay. Genotyping of a sample of positive specimens was performed using reverse-transcription polymerase chain reaction. RESULTS:: A total of 3728 faecal samples were collected and tested during the 4 year surveillance period and 1804 (48.5%) tested rotavirus positive. The highest prevalence of rotavirus diarrhea was found during the dry, cool season. Rotavirus positivity peaked in children 3-17 months of age with almost 80% of cases. Compared with rotavirus-negative cases, rotavirus-positive cases were more likely to be dehydrated (26% vs. 14%, P ≤ 0.001) and have vomiting (77% vs. 57%, P ≤ 0.001) and less likely to have fever (17% vs. 24%, P = 0.03). G9P[8] (43.3%), G1P[8] (11.8%), G2P[4] (8.7%), G2P[6] (8.7%) and G12P[6] (8.7%) were the most common genotypes detected. DISCUSSION:: Rotavirus causes a significant disease burden among children <5 years of age in Zimbabwe. This active surveillance system can serve as a platform to monitor the impact of rotavirus vaccine on disease burden following vaccine introduction.