Circulation of Rotavirus Genotypes and their Distribution among Vaccinated and Non-vaccinated Children in Abuja, Nigeria

Introduction: Nigeria had planned to introduce the rotavirus vaccine in the National Immunisation Programme in 2014 but this has yet to be done. Nigeria has the continent’s highest mortality due to diarrhoeal diseases with little information on specific prevalent genotypes. The main objectives of the study were to identify the predominant rotavirus genotypes and to examine the effects of existing local vaccination programmes on prevailing rotavirus genotypes and on preventing rotavirus diarrhoea.

Methodology: A one-year prospective descriptive study of children under 5 with acute diarrhoea was conducted from September 2012 to August 2013. Children with acute diarrhoea attending three government hospitals and one private hospital were recruited. Children without diarrhoea were also recruited as a control group. Rotavirus ELISA and RNA extraction were done with commercially available kits and positive samples were subjected to RT-PCR and electrophoresis to determine VP7 (G) and VP4 (P) genotypes.

Results: Stool samples were collected from 1240 (93.3%) participants, of whom 957 (77.0%) were ambulatory, 123 (9.9%) hospitalised and 160 (12.8%) controls without diarrhoea. Rotavirus-ELISA was positive among 123 (11.4%) children with diarrhoea. The predominant VP7 genotypes were G2 (n=33, 26.4%) followed by G9 (n=24, 19.2). The main VP4 (P) genotypes included P [4] (n=45, 36.0%) followed by P [6] (n=40, 32.0%). The predominant genotype combinations found were G2 P [4] (n=21, 16.8%), G3 P [6] and G1 P [6] (each n=16, 12.8%), and G12 P [8] (n=15, 12.0%). Very few mixed infections were found in only one government hospital 4 (6.4%). Among 94 unvaccinated children with rotavirus isolates that were genotyped, G2 P [4] (n=19, 20.2%) and G1 P [6] (n=16, 17.0%) were predominant. Among 12 vaccinated children, 2 isolates each (16.6%) were found of G3 P [6], G9 P [4], G12 P [8] and G2 P [NT] with no G1 isolates.

Conclusion: The emergence of new genotypes such as G 12 P [8] found in this study emphasizes the need for continued prospective monitoring of rotavirus at the molecular level to detect new threats to vaccine programmes in future.