Disease burden of Group B Streptococcus among infants in sub-Saharan Africa: a systematic literature review and meta-analysis

Background: Group B streptococcus (GBS) is a leading neonatal sepsis pathogen globally. Investment in GBS disease prevention, such as maternal vaccination, requires evidence of disease burden, particularly in high infant mortality regions like sub-Saharan Africa. We aimed to provide such evidence by conducting a systematic literature review and meta-analysis to estimate maternal colonization proportion, GBS disease incidence, and GBS serotype distribution. Methods: MEDLINE, MEDLINE in process, and Cochrane Library were searched for studies published 1990 – 2014, pertaining to sub-Saharan Africa. Eligible studies were used to estimate the proportion of pregnant women colonized with GBS, early-onset GBS (EOGBS) disease incidence, late-onset GBS (LOGBS) disease incidence, and respective serotype distributions. Random effects meta-analysis was conducted to estimate weighted means and confidence intervals. Results: We identified 17 studies of colonization, nine of disease incidence, and six of serotype distribution meeting inclusion criteria. 21.8% (95% CI 18.3, 25.5) of expectant women were colonized with GBS. The incidence of EOGBS disease was 1.3 per 1000 births (95% CI 0.81, 1.9), that of LOGBS disease 0.73 per 1000 births (95% CI 0.48, 1.0). The most common disease-causing serotype was 3, followed by 1a. Serotypes 1b, 2 and 5 were next most common in frequency. Conclusion: Despite methodologic factors leading to under-estimation, GBS disease incidence appears high in subSaharan Africa. A small number of GBS serotypes cause almost all disease. GBS disease burden in subSaharan Africa suggests that safe, effective, and affordable GBS disease prevention is needed.