Rheumatic Fever

Question 1

What is rheumatic fever?

Answer 1

An inflammatory multisystem disorder, occurring following group A beta-haemolytic streptococci (GAS) infection (ALWAYS CAUSED BY INFECTION OF PHARYNX NOT HEART!!)
AI disease

Question 2

Describe the aetiology of rheumatic fever

Answer 2

UNKNOWN
Streptococcal pharyngeal infection +/- genetic susceptibility triggers RF 2-4 weeks later in the susceptible 2% of the population
Molecular mimicry involved in initiation of tissue injury (antibodies against GAS antigens cross-react with host-antigens)

Question 3

List 5 risk factors for rheumatic fever

Answer 3

Genetic susceptibility (HLA class II) 
Age (4-9 yrs) 
F > M
Seasonality (winter + spring peak) 
Economic factors e.g. poverty, urban environ + crowding

Question 4

Describe the epidemiology of rheumatic fever

Answer 4

Used to have outbreaks before penicillin, esp in children
Common in developing countries but increasingly rare in the West
Peak incidence between 5- 15 years
Mean incidence 19/100,000

Question 5

When does onset of symptoms start in RF? List 3 general symptoms of rheumatic fever

Answer 5

2-5 weeks after pharyngeal GAS infection 
Recent sore throat or scarlet fever 
Malaise  
Fever 
Anorexia

Question 6

Give 2 symptoms affecting the joints in rheumatic fever

Answer 6

Painful, swollen joints

Reduced movement/ function

Question 7

List 3 cardiac symptoms in rheumatic fever

Answer 7

Breathlessness
Chest pain
Palpitations

Question 8

What criteria are used to assess rheumatic fever?

Answer 8

Revised Jones criteria.
Evidence of recent strep infection + 2 major criteria OR 1 major + 1 minor criteria
Evidence of GAS infection:
+ve throat culture: but usually -ve by time sx occur
Rapid strep antigen test +ve
Elevated/rising strep antibody titre
Recent scarlet fever

Question 9

List 5 signs falling under major criteria of rheumatic fever

Answer 9

CASES
CARDITIS: tachycardia, murmurs (mitral/ aortic regurg), pericardial rub, cardiomegaly, conduction defects, signs of cardiac failure
ARTHRTIS: usually larger joints (antibodies against joints)
Subcutaneous nodules: small firm painless nodules seen on extensor surfaces, joints + tendons
ERYTHEMA MARGINATUM: rash with red, raised edges + clear centre mainly on trunk + proximal limbs (antibodies against skin)
SYDENHAMs CHOREA: rapid, involuntary, irregular movements with flowing/ dancing quality (antibodies against brain) AKA servitus dance

Question 10

List 5 signs falling under minor criteria of rheumatic fever

Answer 10

PRAPP
Pyrexia
Raised ESR/CRP
Arthralgia (only if arthritis not present as major criteria)
Prolonged PR interval (only if carditis not present as major criteria)
Previous rheumatic fever
Look out for features of mitral + aortic stenosis. If hear a MS or AS, ask whether they had RF when they were younger

Question 11

What bloods should be taken for rheumatic fever?

Answer 11

WCC elevated
ESR/CRP elevated
Rising antistreptolysin O titre

Question 12

What can be performed with a throat swab for rheumatic fever?

Answer 12

Culture for GAS

Rapid streptococcal antigen test

Question 13

What is seen on histology in rheumatic fever?

Answer 13

Aschoff bodies (granuloma with giant cells)
Anitschkow cells (enlarged macrophages with ovoid, wavy, rod-like nucleus)

Question 14

What is seen on ECG in rheumatic fever?

Answer 14

saddle-shaped ST elevation + PR segment depression (features of pericarditis)
Arrhythmias
(Prolonged PR interval is a minor criterion of acute RF)

Question 15

What is seen on CXR in rheumatic fever?

Answer 15

Chamber enlargement

Congestive cardiac failure

Question 16

What is seen on echocardiogram in rheumatic fever?

Answer 16

Pericardial effusion
Myocardial thickening or dysfunction
Valvular dysfunction

Question 17

Simply explain the proposed pathogenesis of RF. Give 2 examples of when you may consider RF as a spot diagnosis

Answer 17

Strep mimics human antigens on its surface + an antibody is produced against this
Antibodies form against self, which cause carditis (inflamed myocardium) => BP falls
Child with sore throat + then gets a fever + cardiac signs
Elderly with murmur: ask if they had rheumatic fever as a child