Prevalence and Genetic diversity of rotavirus strains among children with gastroenteritis at the Gertrude’s Children’s Hospital, Nairobi, Kenya

Abstract

Rotavirus is the leading cause of severe diarrhoea among infants and young children. Each year more than 527,000 children die from rotavirus gastroenteritis, and two million are hospitalized. The licensing and introduction of two new live oral rotavirus vaccines was expected to substantially reduce child morbidity and mortality due to rotavirus gastroenteritis. This study was aimed at identifying and characterizing rotavirus strains isolated from children with gastroenteritis at the Gertrude’s Children’s Hospital, Nairobi. It was a hospital based cross-sectional study done between January to July 2012 in which 331 patients were randomly selected among those who presented with gastroenteritis and whose parents consented to participate in the study. A structured questionnaire was used to establish their clinical, vaccination status and demographic characteristics. Enzyme-linked immunosorbent assay (ELISA) - based kit was used to detect Group A rotavirus antigens in 298 stool specimen giving a prevalence of 31.5%. Rotavirus dsRNA was extracted from virus particles, separated by polyacrylamide gel electrophoresis (PAGE) and visualized by silver staining. Fifty seven (60.1%) of the specimens gave visible RNA profiles. Thirty eight strains (40.4%) were assigned long electropherotypes while 19 (20.2%) showed short patterns electropherotypes depending on the migration of the 11 genome segments. Eighty three rotavirus antigen positive faecal specimen were selected and dsRNA extracted was reverse-transcribed and amplified using semi-nested RT-PCR in the presence of original consensus primers and genotyped using a mixture of serotype specific primers for the rotavirus genes specifying G (gene 9) and P (gene 4) classification. Forty three VP 7 (G serotype) and twenty six VP 4 (P serotype) were genotyped. Six single genotypes were demonstrated G1, G3, G9, G12, P [4], and P [6] while genotypes G3P [4], G3P [6], G9P [6], G12P [6], were found to be combined. Mixed infections observed included G9/3P [4], G1/3P [4] and G3/9P [6]. G3 were predominant at 27.9% of the G-genotypes detected while P [4] were detected in (16) 61.5 % of all P-genotype detected. Data was entered and analysed by SPSS version 20.0. The data generated from this study adds crucial information on the burden of the rotavirus disease and genotype distribution in Kenya country. Such information not only aids in seeking advocacy for introduction of unusual genotypes into the rotavirus vaccine but also helps in the evaluation of the efficacy of these vaccines in relation to the rotavirus genotypes in circulation. The heterogeneity and ever-changing epidemiology of rotavirus observed in this and other related studies highlight the need for continued surveillance of rotavirus strains throughout Kenya to ensure that vaccination provides optimal protection.