Acute rheumatic fever is an autoimmune condition triggered by streptococcus bacteria. It is caused by antibodies created against the streptococcus bacteria that also target tissues in the body.
It is a multi-system disorder that affects the joints, heart, skin and nervous system. It is rare in the UK due to early treatment of streptococcus with antibiotics.
Rheumatic fever is caused by group A beta-haemolytic streptococcal, typically streptococcus pyogenes causing tonsillitis. The immune system creates antibodies to fight the infection. These antibodies not only target the bacteria, but also match antigens on the cells of the person’s body, for example the muscle cells in the myocardium in the heart.
This results in a type 2 hypersensitivity reaction, where the immune system begins attacking cells throughout the body. This process is usually delayed 2 – 4 weeks after the initial infection.
The typical presentation of rheumatic fever occurs 2 – 4 weeks following a streptococcal infection, such as tonsillitis. Symptoms affect multiple systems, causing:
- Joint pain
- Shortness of breath
Rheumatic fever causes a migratory arthritis affecting the large joints, with hot, swollen, painful joints. It is migratory because different joints become inflamed and improve at different times, giving the appearance that the arthritis is moving from one joint to the next.
Carditis, or inflammation throughout the heart, with pericarditis, myocarditis and endocarditis, leads to:
- Tachycardia or bradycardia
- Murmurs from valvular heart disease, typically mitral valve disease
- Pericardial rub on auscultation
- Heart failure
There are two key skin findings with rheumatic fever:
- Subcutaneous nodules
- Erythema marginatum rash
Firm painless nodules occur over extensor surfaces of joints, such as the elbows. The erythema marginatum rash involves pink rings of varying sizes affecting the torso and proximal limbs.
Nervous system involvement:
Chorea is the key nervous system symptom. This involves irregular, uncontrolled and rapid movements of the limbs. This is also known as Sydenham chorea and historically as St Vitus’ Dance.
Investigations that can help support the diagnosis include:
- Throat swab for bacterial culture
- ASO antibody titres
- Echocardiogram, ECG and chest xray can assess the heart involvement
A diagnosis of rheumatic fever is made using the Jones criteria (see below).
Antistreptococcal Antibodies Titres
Anti-streptococcal antibodies (ASO) are antibodies against streptococcus. They indicate a recent streptococcus infection and can be helpful in supporting a diagnosis of rheumatic fever. After an acute infection the levels usually:
- Rise over 2 – 4 weeks
- Peak around 3 – 6 weeks
- Gradually falls over 3 – 12 months
ASO levels are usually repeated after 2 weeks to:
- Confirm a negative test
- Assess whether levels are rising or falling
Jones Criteria for Diagnosis
A diagnosis of rheumatic fever can be made when there is evidence of recent streptococcal infection, plus:
- Two major criteria OR
- One major criteria plus two minor criteria
The mnemonic for the Jones criteria is JONES – FEAR.
- J – Joint arthritis
- O – Organ inflammation, such as carditis
- N – Nodules
- E – Erythema marginatum rash
- S – Sydenham chorea
- ECG Changes (prolonged PR interval) without carditis
- Arthralgia without arthritis
- Raised inflammatory markers (CRP and ESR)
Treatment of streptococcal infections with antibiotics helps prevent the development of rheumatic fever. Tonsillitis caused by streptococcus should be treated with phenoxymethylpenicillin (penicillin V) for 10 days.
Patients with clinical features of rheumatic fever should be referred immediately for specialist management. Management involves medications and follow up:
- NSAIDs (e.g. ibuprofen) are helpful for treating joint pain
- Aspirin and steroids are used to treat carditis
- Prophylactic antibiotics (oral or intramuscular penicillin) are used to prevent further streptococcal infections and recurrence of the rheumatic fever. These are continued into adulthood.
- Monitoring and management of complications
- Recurrence of rheumatic fever
- Valvular heart disease, most notably mitral stenosis
- Chronic heart failure
Last updated January 2020