Assessment of Anti-Streptolysin O Titre in Healthy School Age Children in El Behira Governorate

Background: Group-A streptococcal serology is used for post-streptococcal disease diagnoses, such as acute rheumatic fever, and occasionally for diagnosis of streptococcal pharyngitis. The prevalence of rheumatic fever in school children aged 6 to 15 years ranges between 0.2 to 0.75 per 1000 children per year. The prevalence of rheumatic heart disease in 1000 children ranges from 1 to 5.4.  Aim of the work: To determine upper limit of the normal range of Antistreptolysin O titre in healthy school children, aged 6-15 years old in El Behira governorate. Patients and Methods:A cross-sectional study had been performed in EL Behira Governorate and the collected sample were tested in clinical pathology Lab [Al-Azhar University Hospital, Damietta]. A total of 3000 [1609 Males, 1391 Females] serum samples had been collected from children aged 6-15 years, had been tested for Anti-streptolysin O titer [ASO] by turbidimetry. Results: Normal value for the ASO titer rose sharply during early childhood and then declined gradually with age. The estimated titer that was 80% of the upper limit or normal at age 10 years was 287 IU/ml for ASO. Conclusion: This study provides the upper limit of normal value for ASO titre of school children. The "more than 400" rating should instruct clinicians in the treatment of post-streptococcal diseases in patients and provide valuable longitudinal evidence for potential intervention trials against streptococcal diseases in group A.