Inflammation of joints as a result of an abnormal immune response to a recent infection elsewhere in the body
- Most common between the ages of 20 and 40
- More common in males
- Sometimes runs in families
- Lifestyle as a risk factor depends on the cause
Reactive arthritis is usually a short-term disorder that develops after a bacterial infection of the genital tract, such as chlamydial infection or nongonococcal urethritis, or the intestinal tract (see Gastroenteritis). Any of these infections may stimulate an abnormal immune response that causes tissues in the joints, usually the knee or ankle, to become inflamed. If inflammation also affects the eyes or the genital tract, the condition is known as Reiter’s syndrome.
About 8 in 10 people who develop Reiter’s syndrome have a particular antigen (a substance capable of stimulating an immune response in the body) known as HLA-B27. Although Reiter’s syndrome is induced by infection, it usually develops in people who have a genetic predisposition to it. The disorder may therefore run in families.
What are the symptoms?
Depending on the infection that has triggered reactive arthritis or Reiter’s syndrome, you may experience symptoms of a genital infection, such as pain on passing urine, or symptoms of gastroenteritis, such as diarrhoea. However, some people have no initial symptoms.
Both conditions develop 3–30 days after the initial infection has appeared. Symptoms may include:
Painful, red, tender joints.
Swelling around the joints.
Although the knees or ankles are most commonly affected, other joints may also be involved. If you have Reiter’s syndrome, you may also notice:
Pain on passing urine and a discharge from the penis or vagina.
What might be done?
Your doctor may diagnose reactive arthritis or Reiter’s syndrome from your medical history and symptoms. He or she will probably take swabs from your urethra or cervix or collect a stool sample to try to establish the source of infection. Further tests may include a blood test to detect signs of inflammation and an X-ray to look for evidence of joint damage.
If you are still affected by a genital or intestinal infection, your doctor may prescribe oral antibiotics. To relieve pain in your joints, he or she may recommend a nonsteroidal anti-inflammatory drug. If the pain is very severe and there is no infection present in the joint itself, you may be given a corticosteroid drug, injected directly into the joint (see Locally acting corticosteroids).
What is the prognosis?
The symptoms usually last for less than 6 months, and most people recover fully from reactive arthritis or Reiter’s syndrome. People who are susceptible to Reiter’s syndrome can reduce the risk of recurrence by taking care with personal hygiene and practising safe sex.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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