Arthritis means inflammation of one or more joints. Reactive arthritis is caused when a joint 'reacts' to an infection elsewhere in the body. The infection which triggers reactive arthritis is not actually in the joint, but is usually in the gut or urethra.
Infection of the urethra (urethritis) is the most common trigger. About 1 in 100 people who have an infection of the urethra also develop reactive arthritis. The urethra is the tube that passes urine out from the bladder. Some sexually transmitted infections can cause urethritis, but infection with bacteria called chlamydia is the most common. Symptoms of the infection include a discharge from the urethra, and pain when you pass urine.
Reactive arthritis mostly affects young men. It is frequently associated with the human leukocyte antigen B27 (HLA-B27) haplotype and is classified with the seronegative spondyloarthropathies. Reactive arthritis is preferably viewed as a tetrad, with the addition of the mucocutaneous findings of balanitis and keratoderma blennorrhagicum to the classic triad. The complete and incomplete forms of reactive arthritis can be identified by the presence or absence of the full tetrad.
Reactive arthritis is a condition that causes inflammation, pain and swelling of the joints. It usually develops after an infection, often in the bowel or genital areas. The infection causes activity in the immune system. The normal role of your body's immune system is to fight off infections to keep you healthy. In some people this activity of the immune system causes joints to become inflamed, however the joints themselves are not actually infected.
Reactive arthritis usually occurs following an infection in a genetically susceptible person. Over two thirds of these patients are HLA-B27 positive. Those who are negative frequently are positive for cross-reacting antigens such as B7, B22, B40 and B42.8 A recent study9 found a similarity between some peptides found in gram-negative organisms and peptides that are in the binding site of the B27 molecule.
Chronic (i.e., long-lasting) reactive arthritis may need to be treated with a disease modifying anti-rheumatic drug (DMARD) such as sulfasalazine or methotrexate. These medications take longer to become fully effective, but can bring about remission. In some cases very inflamed joints may be injected with corticosteroids.
Conjunctivitis, an inflammation of the mucous membrane that covers the eyeball and eyelid, develops in approximately half of people with reactive arthritis. Some people may develop uveitis, which is an inflammation of the inner eye. Conjunctivitis and uveitis can cause redness of the eyes, eye pain and irritation, and blurred vision. Eye involvement typically occurs early in the course of reactive arthritis, and symptoms may come and go.
The second commonest cause is an infection of the gut, such as food poisoning or dysentery. Between 1 and 2% of people involved in any outbreak of food poisoning may suffer joint inflammation afterwards. Often, reactive arthritis will be reported following a tummy upset or diarrhoea. More rarely, reactive arthritis may follow a sexually acquired infection of the urethra or cervix, which may be shown by pain on passing urine or by a discharge from the vagina or penis. The doctor may ask about sexual activity in patients with possible reactive arthritis.
Reactive arthritis may be self limiting, frequently recurring, chronic or progressive. Most patients have severe symptoms lasting a few weeks to six months. Approximately 15 to 50 percent of cases have recurrent bouts of arthritis. Chronic arthritis or sacroiliitis occurs in 15-30 percent of cases.
