Background & objectives: For the serodiagnosis of group A streptococcal (GAS) infections and their late sequelae, a battery of tests have been suggested. However, anti-streptolysin O (ASO) and antideoxyribonuclease B (ADNase B) are the most widely accepted tests for the same. It is essential to evaluate the upper limits of ASO and ADNase B levels in age and sex matched normal population before using them for the detection of patients. For this study, these values were determined in the past and were revaluated again in 2001-2002, in normal subjects.
Methods: A total of 200 healthy individuals were included in the study in 1991-1992 and same number of age and sex matched healthy individuals were included in 2001-2002. The methodology used for determination of ASO and ADNase B levels were as per the techniques recommended by the WHO.
Results: The findings show that the upper limits of normal ASO titers are 195 IU and 305 IU for adults and children respectively while the said levels for ADNase B for both adults and children were found to be 200 IU.
Interpretation & conclusion: The findings of the present study will be helpful in the follow-up, better diagnosis and prognosis of group A streptococcal infections.