Rheumatic fever is difficult to diagnose in adults.
The diagnosis is suggested by the abrupt onset of very painful synovitis that usually involves the lower extremities and responds dramatically to aspirin therapy. A study in Iraq involving 32 patients who had rheumatic fever sheds some light on the incidence of the disease's clinical features. Lower limb joints were more involved than upper limb joints. Mild carditis occurred in only one patient. Although all had evidence of antecedent streptococcal infection, none had chorea, subcutaneous nodules, or erythema marginatum.