Rotavirus strain types circulating in Africa: Review of studies published during 1997-2006.

Rotavirus is responsible for more than half a million deaths among infants and young children worldwide each year; many of these deaths could be prevented by widespread use of an effective rotavirus vaccine. The diversity of rotavirus strains in many developing countries, where most rotavirus deaths occur, could represent a significant challenge to the efficacy of current vaccines. In anticipation of rotavirus vaccine introduction, we examined studies published over a 10-year period (1997-2006) from countries in Africa that examined the distribution of VP7 (G) and VP4 (P) rotavirus strain types in symptomatic children and in neonates, together with studies that undertook a more detailed characterization of unusual rotavirus strains. Compared with recently published global reviews of rotavirus strain types and a previous review of the African literature published before 1997, the current data indicate a substantially increased diversity of rotavirus strains across the continent. Notable findings included a reduction in the proportion of globally common serotypes; a high proportion of unusual P/G combinations, suggesting viral reassortment; evidence for zoonotic rotavirus transmission; the emergence and spread across Africa of serotype G9; and a high prevalence of the P[6] VP4 genotype. These data imply that rotavirus vaccines will need to confer protection against a wide variety of strain types in Africa and emphasize the importance of continued strain surveillance before and after the introduction of routine rotavirus vaccination.