Reactive arthritis is a form of arthritis, or joint inflammation, that occurs as a "reaction" to an infection elsewhere in the body. Inflammation is a characteristic reaction of tissues to injury or disease and is marked by swelling, redness, heat, and pain. Besides this joint inflammation, reactive arthritis is associated with two other symptoms: redness and inflammation of the eyes (conjunctivitis) and inflammation of the urinary tract (urethritis). These symptoms may occur alone, together, or not at all.
Reactive arthritis is also known as Reiter's syndrome. Doctors also refer to it as seronegative spondyloarthropathy. The seronegative spondyloarthropathies are a group of disorders that can cause inflammation throughout the body, especially in the spine. (Examples of other disorders in this group include psoriatic arthritis, ankylosing spondylitis, and the kind of arthritis that sometimes accompanies inflammatory bowel disease.)
In many patients, reactive arthritis is triggered by a venereal infection in the bladder, the urethra, or, in women, the vagina (the urogenital tract) that is often transmitted through sexual contact. This form of the disorder is sometimes called genitourinary or urogenital reactive arthritis. Another form of reactive arthritis is caused by an infection in the intestinal tract from eating food or handling substances that are contaminated with bacteria. This form of arthritis is sometimes called enteric or gastrointestinal reactive arthritis.
The symptoms of reactive arthritis usually last 3 to 12 months, although symptoms can return or develop into a long-term disease in a small percentage of people.
What Causes Reactive Arthritis?
Reactive arthritis typically begins about 1 to 3 weeks after infection. The bacterium most often associated with reactive arthritis is Chlamydia trachomatis, commonly known as chlamydia. It is usually acquired through sexual contact. Some evidence also shows that respiratory infections with Chlamydia pneumoniae may trigger reactive arthritis.
Infections in the digestive tract that may trigger reactive arthritis include Salmonella, Shigella, Yersinia, and Campylobacter. People may become infected with these bacteria after eating or handling improperly prepared food, such as meats that are not stored at the proper temperature.
Doctors do not know exactly why some people exposed to these bacteria develop reactive arthritis and others do not, but they have identified a genetic factor, human leukocyte antigen (HLA) B27, that increases a person's chance of developing reactive arthritis. Approximately 80 percent of people with reactive arthritis test positive for HLA-B27. However, inheriting the HLA-B27 gene does not necessarily mean you will get reactive arthritis. Eight percent of healthy people have the HLA-B27 gene, and only about one-fifth of them will develop reactive arthritis if they contract the triggering infections.