ASO Titres are used in the diagnosis of

Rheumatic fever is an acute, immunologically mediated, multisystem inflammatory disease that occurs after group A b-hemolytic streptococcal infections (usually pharyngitis, but also rarely with infections at other sites such as skin). Rheumatic hea disease is the cardiac manifestation of rheumatic fever. It is associated with inflammation of all pas of the hea. Although cultures are negative for streptococci at the time of symptom onset, serum titers to one or more streptococcal antigens (e.g., streptolysin O or DNAase) usually are elevated. (Robbins Basic Pathology,9th edition,pg no. 392)