Epidemiology of streptococcal infection with reference to Rheumatic fever

Abstract

Introduction: Group A hemolytic streptococcal infections have a worldwide distribution among children and it poses an important health problem globally. Group A streptococcal (GAS) serology is used for the diagnosis of post-streptococcal diseases, such as acute rheumatic fever, post-streptococcal Glomerulonephritis and occasionally for the diagnosis of streptococcal pharyngitis. Upper normal limits for streptococcal serology should be determined for individual populations because of differences in the epidemiology of GAS between populations. Material & Methods: Study materials were divided in 3 groups. Group-A (normal children population), group- B (children clinically diagnosed as acute bacterial sore throat) and group-C (children clinically diagnosed rheumatic fever). ASO titer & throat culture were assessed in all three groups. Result: When cut off range of ASO titer is >200 IU/ml, it is positive in 20%, 38% and 54.4% in Group A, B and C respectively. But When titer range increased to >400 IU/ml, it was positive in 40 %, 36.84% and 44.44% cases from Group A, B & C respectively. Conclusion: Cut off point of 200 IU/ml has limitations in our setup. Use of western cut off 200 IU/ml needs to be revised in relation to local epidemiology to get less false positive results.