Characterization of Rotavirus Strains in Ghana Before and After Vaccine Introduction

Abstract

Rotavirus is the most common etiologic agent of diarrheal disease among infants and children globally and causes 196,000 deaths among children under age 5 each year, predominantly in developing settings. Rotaviruses are composed of a segmented dsRNA genome surrounded by a triple-layered protein coat. Unique features in two of those coat proteins, described by a G type and a P type, are used to identify a rotavirus’ strain. Many different strains co-circulate, and their distribution varies geographically and temporally. Two rotavirus vaccines are currently being introduced around the world, but there are concerns that they may facilitate strain replacement, in which any reductions in the prevalence of targeted rotavirus strains would be offset by increases in non-targeted ones. This investigation looks for changes in the distribution of rotavirus strains circulating in Ghana between the periods of time two years before and two years after the initiation of an immunization program in May 2012. It reports that G12 strains, which emerged in Ghana in 2008 and were documented only sporadically through 2011, caused 53% of infections before vaccination and 45% after vaccination began. Most vaccination-era G12 isolates were G12P[8] and displayed the same electropherotype, suggesting dominance of a single genetic lineage. The prevalence of G1P[8], the vaccine-targeted strain, decreased from 10% of cases before vaccination to 1% after vaccination began. By serving as a baseline for continued surveillance in subsequent years, these results are relevant for health personnel in Ghana and in other countries considering initiating their own rotavirus vaccine programs.