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 reversetranscribed 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.