β-hemolytic streptococcal throat carriage and tonsillopharyngitis: a cross-sectional prevalence study in Gabon, Central Africa

Group A streptococcus (GAS) and possibly other beta-hemolytic streptococci (BHS) account for a considerable morbidity and mortality burden in African populations; however, disproportionately little is known about the epidemiology of BHS in sub-Saharan Africa. This study assessed the prevalence of GAS, group G streptococcus (GGS) and group C streptococcus (GCS) carriage and tonsillopharyngitis in a Central African population. A prospective cross-sectional study was performed to assess the prevalence of and risk factors for BHS carrier status and tonsillopharyngitis in children and adults in Gabon. The overall BHS carrier prevalence was 135/1,005 (13.4 %); carrier prevalence of GAS, GGS, and GCS was 58/1,005 (5.8 %), 50/1,005 (5.0 %), and 32/1,005 (3.2 %), respectively. Streptococcal carriage was associated with school and pre-school age (adjusted OR 2.65, 95 % CI 1.62-4.36, p = 0.0001 and 1.90, 95 % CI 1.14-3.17, p = 0.0141, respectively). Participants residing in urban areas were less likely carriers (OR 0.52, p = 0.0001). The point-prevalence of BHS-positive tonsillopharyngitis was 1.0 % (9/1,014) and 15.0 % (6/40) in school children with sore throat. Non-GAS exceeded GAS throat carriage and tonsillopharyngitis suggesting a yet underestimated role of non-GAS streptococci in BHS diseases.