What is the cause of rheumatic fever?
- The disease starts with a throat or skin infection with a particular germ (bacterium) called a Lancefield group A beta-haemolytic streptococcus.
- Usually this bug just causes a really sore throat or a bad skin infection which can be easily treated with the antibiotic penicillin.
- For most people that is the end of the problem but in rheumatic fever your immune system goes into overdrive.
- Your immune system thinks it can recognise bits of the streptococcus bug in your joints, heart and nervous system and so accidentally attacks them.
Where in the world is rheumatic fever most common?
- Until about the mid-1900s rheumatic fever was found in the UK and other western countries. But since antibiotics have become widespread it has practically disappeared from the UK.
- In Africa, India and rural parts of Australia and New Zealand people still get rheumatic fever: roughly 1 in 300 teenagers will get it each year in those areas.
- The disease is mainly related to a lack of antibiotics and also to poor social conditions like overcrowding.
What age group is most affected by rheumatic fever?
- The main age range is 8 to 14 years.
- The peak age for the disease is 10 years old.
How do doctors diagnose rheumatic fever?
- The diagnosis is usually made by the history of a sore throat or a bad skin infection followed, a few weeks later, by the typical features and symptoms.
- A blood test to show a recent infection with the streptococcus bacterium (called an antistreptolysin titre) can help to confirm that the bacterium has been in your body.
- But then there is a scoring system using major criteria and minor criteria. You need two majors, or one major and two minors, to make the diagnosis.
- The major criteria are the main symptoms:
- Joint pains.
- Heart problems.
- Jerky movements (called chorea).
- Skin problems.
- The minor criteria are:
- A high temperature (fever), usually over 39°C.
- A high blood test result showing inflammation in your body (what doctors call an ESR or a CRP).
- Changes on a heart trace (what doctors call a prolonged PR interval).
- To see the problems on the heart, a specialist will usually use an echocardiogram: a special scan to see the inside of the heart. But in many parts of the developing world there are not echocardiograms available.
Further reading and references
Patient-friendly guide to rheumatic fever; Mayo Clinic
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