Epidemiology of streptococcal infection with reference to rheumatic fever.

ABSTRACT

Antistreptolysin antibodies were estimated in 787 normal children and young adults by latex test. This test detects titres of 200 IU/ml and above, which is the western cut off point, for diagnosis. Children below one year showed no antibodies. Unlike western studies where no antibodies are detected below the age of 3 years, our study revealed that 7.9% children between 1-3 years had significantly elevated antibodies. This epidemiological pattern is well reflected in the different clinical profile of younger children developing rheumatic heart disease in our country. Antibodies progressively increased with age--11.8% in 4-8 years group to 15.8% in 9-12 years age group. All these were from the lower socio-economic group. ASO was positive in 16.7% of young adults from lower socio-economic status while it was positive only in 9.2% in the upper socio-economic status. A total of 522 patients of rheumatic carditis were studied. Only 23.4% had no antibodies or less than 200 IU/ml, and 77% were positive (26.9% had greater than 400 IU/ml and 49.7% had 200 IU/ml). Throat swab culture and ASO antibodies were done simultaneously in 76 outdoor patients, clinically diagnosed as acute bacterial pharyngitis. Group A beta hemolytic streptococci were isolated in 64% and significant antistreptolysin antibodies were seen in 62%. School health records were scanned in more than 50,000 school children. Point prevalence of rheumatic heart disease was estimated to be 0.17% in lower and 0.05% in upper socio-economic groups. Age and socio-economic factors are important variables in epidemiology of streptococcal infection.(ABSTRACT TRUNCATED AT 250 WORDS)