Rheumatic Fever Flashcards
Define rheumatic fever.
An inflammatory multisystem disorder, occurring following a recent (2-4 weeks ago) GAS infection
What is the pathogenesis of rheumatic fever?
There is molecular mimicry between Group A streptococcus pyogenes antigens and human host tissue causing cross reactivity. The antigens cross react with several cardiac proteins but valves are most affected. Electrical conduction can also be affected due to
How common is rheumatic fever? When does it usually occur?
Mostly in developing countries
Has improved due to better living conditions and hygiene and decreased GAS transmission.
What are the risk factors for rheumatic fever?
Risk factors for GAS disease:
- Poverty
- Overcrowding
- FH of rheumatic fever
- D8/17 B cell antigen positivity
- HLA association
- genetic susceptibility
- indigenous populations: aboriginal Australian, Asian, Pacific Islanders
How do you diagnose rheumatic fever?
No single test can diagnose it - diagnosis is clinical and based on the Jones criteria.
JONES criteria -
-
Evidence of GAS infection AND
- [Initial infection] 2major criteria, or 1major+2minor criteria.
- [Recurrent infection] 2major, 1major and 2minor, or 2minor manifestations
How might you investigate for GAS infection?
Evidence for GAS infection:
- +ve throat culture
- rapid strep Ag test
- anti-streptolysin O
- DNase B titre
- recent scarlet fever
What are the major Jones criteria? What are the main clinical features of acute rheumatic fever?
JONES major:
- Joints - migratory arthritis of large joints; tenderness, swelling, erythema
- O- Heart –> pancarditis (peri,myo,endocarditis), new murmur (Carey Coombs murmur - mid diastolic)
- Nodules, s.c. –> painless nodules on extensor surface
- Erythema marginatum - annular erythema with pale centre on trunk and proximal limbs.
- Sydeham’s chorea - rapid, involuntary, irregular movements with flowing/dancing quality in limbs, slurred speech, facial grimacing (seen more in females)
The major manifestations: carditis and arthritis, followed in descending frequency by chorea (with a female predominance), subcutaneous nodules, and erhythema marginatum (uncommon but specific of ARF).
What is the main murmur heard in acute rheumatic fever?
Carey Coombs murmur -
- due to mitral valvulitis
- short, mid-diastolic rumble
- best heard at the apex
- disappears as the valvulitis improves
What are the minor Jones criteria?
- Pyrexia >38.5oC
- Arthralgia
- Increase inflammatory markers ESR, CRP, WCC
- Prolonged PR interval on ECG
What investigations would you do for RF?
- FBC, ESR/CRP - minor criteria
- Antistreptolysin O titre - serology test; do acutely then another at 10-14days
- Throat swabs - culture for GAS , rapid strep antigen test but these are often negative so serology needed
- ECG - prolonged PR
- Echocardiogram - pericardial effusion, myocardial thickening or dysfunction, valvular dysfunction
What is the management of rheumatic fever?
No treatments affect the outcome of ARF but some shorten the inflammation. All patients with ARF should be ADMITTED to confirm diagnosis and observe.
- NSAIDs/aspirin - help polyarthritis. Only start once diagnosis confirmed as will mask symptoms, otherwise use paracetamol.
- Bed rest - esp in carditis with HF features +/- ACEi.
- Benpen 600,000 units IM single dose - eradicates strep in the throat [Allergy: erythromycin PO QDS for 10days]
- Sodium valproate - only for severe cases of chorea
Other:
Secondary prevention - Benpen injections - long-lasting penicillin every 3-4 weeks. If allergic: oral erythromycin
Valvular replacement - in severe disease with reduced ventricular function
Of all the organs affected by acute rheumatic fever which is the one that is chronically affected?
Only the effects on the heart can lead to permanent illness*→ heart valves damaged → chronic rheumatic heart disease.
*Without long-term penicillin prophylaxis
What is the diagnosis?
A 10-year-old Samoan girl presents with a 2-day history of fever and sore joints. Further questioning reveals that she had a sore throat 3 weeks ago but did not seek medical help at this time. Her current illness began with fever and a sore and swollen right knee that was very painful. The following day her knee improved but her left elbow became sore and swollen. While in the waiting room her left knee is now also becoming sore and swollen.
Acute rheumatic fever
What is the most common presentation of ARF?
Arthritis - large joint migratory polyarthritis which easily responds to NSAIDs
AND fever
What are the complications of ARF?
Rheumatic heart disease - 30-50% develop this; usually mitral valve disease; sometimes AF or CHF.
What is this?
Erythema marginatum
What is this?
Livedo reticularis
