Antistreptolysin O (ASO) titers and beta-haemolytic streptococcus (BHS) in Children in Calabar, Nigeria

This study investigated the prevalent ASO titer values and serogroups of BHS prevalent in the throat of apparently healthy children in Calabar with the aim of detecting the risk in the children of developing RF and RHD in their later years. The throats of 437 children drawn randomly from elementary schools in three communities in Calabar, Nigeria were examined and throat swabs collected. Fifty children clinically diagnosed with bacterial pharyngitis were used as control. Throat swabs were cultured aerobically on goat blood agar in an atmosphere of 5-10% carbon-dioxide and grouped serologically using the Strep PRO grouping kit. ASO titers in the sera of 437 subjects were determined by the Rheumajet ASO 500T. Culture of the 437 throat specimens yielded 90(20.6%) Streptococcal species belonging to 5 groups, 4 of which were definite and included C, D, F and G. The fifth group was not identified by the available grouping kit. The most prevalent Streptococcus group in the study was group C with 32(35.6%) isolates. The most frequently occurring ASO titer was 400IU/mL, obtained from 186/437(42.5%) subjects, with those in Group C associated with high titers (30; 93%). Overall, the mean ASO titers for test and control subjects were 902IU/mL and 929IU/mL respectively. There was a positive correlation (r=0.5, P=0.000) between presence of Streptococci in the throats and high ASO titers in the sera of subjects. The study established a high prevalence of BHS in the throat of children in Calabar howbeit, with no evident risk of RF and RHD as no Group A Streptococcus was isolated.