<prompt> ASO titire Is diagnostic in ?SABERheumatoid ahritisInfective endocarditisAcute rheumatic fever  <response>: Ref: R Alagappan - Manual of Practical Medicine 4th Edition.pg no:146-147 Essential Criteria Evidence for recent streptococcal infection as evidenced by: 1. Increase in ASO titre a. 333 Todd units in children b. 250 Todd units in adults. 2. Positive throat culture for streptococcal infection. 3. Recent history of scarlet fever. Two major or one major and two minor criteria, in the presence of essential criteria, is required to diagnose Acute Rheumatic Fever. A Positive Rheumatic Fever history is usually elicited in only 50 of patient with Rheumatic Hea Disease. 