Rheumatic Fever (ASO) Test - Anti-Streptolysin O (ASO) Titer Test

This serological test measures the titer of IgG antibodies directed against streptolysin O toxin, an enzyme produced by Group A Streptococcus (GAS) bacteria. The production of these antibodies increases in response to infection with this bacterium. It is not used to diagnose acute infections, but rather to confirm a previous streptococcal infection. It is important in diagnosing non-purulent complications following infection, such as rheumatic fever and acute poststreptococcal glomerulonephritis.