Which one of the following is not true about the development of acute rheumatic fever?
A. It develops during the acute phase of a group A beta-hemolytic streptococcal infection of the throat.
B. It is not associated with streptococcal infection of sites other than the pharynx.
C. It usually occurs during the course of epidemics of streptococcal throat infections in crowded settings.
D. It is far more common in underdeveloped countries than in the United States.
E. Its lesions involve the heart, joints, skin and nervous system.
The Correct Answer is A
Acute rheumatic fever is triggered by infection with specific strains of group A streptococci which possess antigens that cross-react with human connective tissue, particularly heart valve glycoprotein.
The condition usually affects children or young adults, and there is a familial variation in susceptibility. Its prevalance in Western Europe and North America has progressively declined to very low levels, but it remains common in parts of asia, africa and south america, where it is still the most common cause of acquired heart disease in childhood adolescence.
Rheumatic fever is a systemic illness typically presenting with fever, anorexia, lethargy and joint pains. Arthritis occurs in approximately 75% of patients and other features include skin rashes, carditis and neurological features.
Anti-streptococcal antibody, anti-streptolysin antibody, positive culture for group A streptococcus, recent scarlet fever.
Erythema marginatum (the expanding erythematous rash) and Sydenham chorea (rapid, purposeless movements) also accompany this disorder.
Carditis is the most important manifestation of rheumatic fever. Carditis presents as breathlessness, palpitations or chest pain.
Other features consist of tachycardia, cardiac enlargement and new or changed cardiac murmurs.
A soft systolic murmur is common but non-specific. However, a soft mid-diastolic murmur is often due to valvulitis, with nodules forming on the mitral valve leaflets.
There is a pericardial friction rub which is often intermittent. Cardiac failure may result either from impaired function of ventricular muscle or from mitral or aortic incompetence and tends to occur in a ‘fulminant’ form of rheumatic fever that is more common in developing countries. Electrocardiographic changes include ST or T wave changes; conduction defects sometimes occur and may cause syncope. Mitral valve becomes thickened with fused chorda tendinae. Aortic regurgitation occurs.
Complications of rheumatic fever include
- cardiac arrhythmias
- rheumatic pneumonitis
- pulmonary embolism
- pulmonary infarction
- valve deformity, and
- in extreme cases, congestive heart failure.