Reactive arthritis is a form of arthritis that occurs as a "reaction" to an infection elsewhere in the body. Besides joint inflammation - marked by swelling, redness, heat, and pain - 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, and doctors might also refer to it by another term, as a seronegative spondyloarthropathy.

In many patients, reactive arthritis is triggered by an infection in the bladder, the urethra, or, in women, the vagina (the urogenital tract) that is often transmitted through sexual contact. 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.

Overall, men between the ages of 20 and 40 are most likely to develop reactive arthritis. However, evidence shows that although men are nine times more likely than women to develop reactive arthritis due to sexually acquired infections, women and men are equally likely to develop reactive arthritis as a result of food-borne infections. Women with reactive arthritis often have milder symptoms than men.

Causes

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 might trigger reactive arthritis.

Reactive arthritis typically begins about 1 to 3 weeks after infection.

Infections in the digestive tract that might 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 that increases a person's chance of developing reactive arthritis. Approximately 80% of people with reactive arthritis test positive for this gene, but inheriting it does not necessarily mean you will get reactive arthritis.

Reactive arthritis is not contagious, however, the bacteria that can trigger reactive arthritis can be passed from person to person.

Symptoms

Reactive arthritis most typically results in inflammation of the urogenital tract, the joints, and the eyes. Less common symptoms are mouth ulcers and skin rashes. Any of these symptoms may be so mild that patients do not notice them. They usually come and go over a period of several weeks to several months.

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.

Urogenital Tract Symptoms

Reactive arthritis often affects the urogenital tract, including the prostate or urethra in men and the urethra, uterus, or vagina in women. Men may notice an increased need to urinate, a burning sensation when urinating, and a fluid discharge from the penis. Some men with reactive arthritis develop inflammation of the prostate gland, which can cause fever and chills, an increased need to urinate, and a burning sensation when urinating.

Women with reactive arthritis may develop problems in the urogenital tract, such as inflammation of the cervix or urethra, which can cause a burning sensation during urination. In addition, some women also develop inflammation of the fallopian tubes or of the vulva and vagina. These conditions may or may not cause any arthritic symptoms.

Joint Symptoms

The arthritis associated with reactive arthritis typically involves pain and swelling in the knees, ankles, and feet. Wrists, fingers, and other joints are affected less often. People with reactive arthritis commonly develop inflammation of the tendons or at places where tendons attach to the bone. In many people with reactive arthritis, this results in heel pain or irritation of the Achilles tendon at the back of the ankle. Some people with reactive arthritis also develop heel spurs, which are bony growths in the heel that may cause chronic (long-lasting) foot pain. Approximately half of people with reactive arthritis report low-back and buttock pain.

Reactive arthritis also can cause spondylitis (inflammation of the vertebrae in the spinal column) or sacroiliitis (inflammation of the joints in the lower back that connect the spine to the pelvis).

Eye Involvement

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.

Other Symptoms

Between 20% and 40% of men with reactive arthritis develop small, shallow, painless sores on the end of the penis. A small percentage of men and women develop rashes or small, hard nodules on the soles of the feet and, less often, on the palms of their hands or elsewhere. In addition, some people with reactive arthritis develop mouth ulcers that come and go. In some cases, these ulcers are painless and go unnoticed.

Diagnosis

Doctors sometimes find it difficult to diagnose reactive arthritis because there is no specific laboratory test to confirm that a person has it.

At the beginning of an examination, the doctor will probably take a complete medical history and note current symptoms as well as any previous medical problems or infections. Before and after seeing the doctor, it is sometimes useful for the patient to keep a record of the symptoms that occur, when they occur, and how long they last. It is especially important to report any flu-like symptoms, such as fever, vomiting, or diarrhea, because they may be evidence of a bacterial infection.

The doctor may use various blood tests to help rule out other conditions and confirm a suspected diagnosis of reactive arthritis.

The doctor also is likely to perform tests for infections that might be associated with reactive arthritis. Patients generally are tested for a Chlamydia infection because recent studies have shown that early treatment of Chlamydia-induced reactive arthritis may reduce the progression of the disease. The doctor may look for bacterial infections by testing cell samples taken from the patient's throat as well as the urethra in men or cervix in women. Urine and stool samples also may be tested. A sample of synovial fluid (the fluid that lubricates the joints) may be removed from the arthritic joint. Studies of synovial fluid can help the doctor rule out infection in the joint.

Doctors sometimes use x-rays to help diagnose reactive arthritis and to rule out other causes of arthritis. X-rays can detect some of the symptoms of reactive arthritis, including spondylitis, sacroiliitis, swelling of soft tissues, damage to cartilage or bone margins of the joint, and calcium deposits where the tendon attaches to the bone.

Treatment

A person with reactive arthritis probably will need to see several different types of doctors because reactive arthritis affects different parts of the body.

However, it may be helpful to the doctors and the patient for one doctor, usually a rheumatologist (a doctor specializing in arthritis), to manage the complete treatment plan. This doctor can coordinate treatments and monitor the side effects from the various medicines the patient may take.

Although there is no cure for reactive arthritis, some treatments relieve symptoms of the disorder. The doctor is likely to use one or more of the following treatments:

* Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce joint inflammation. Some traditional NSAIDs, such as aspirin and ibuprofen, are available without a prescription, but others that are more effective for reactive arthritis must be prescribed by a doctor.

* Corticosteroid injections directly into the affected joint may reduce inflammation.

* Topical corticosteroids reduce inflammation and promote healing. They come in a cream or lotion and can be applied directly on the skin lesions, such as ulcers, associated with reactive arthritis.

* Antibioticsmight be prescribed to eliminate the bacterial infection that triggered reactive arthritis.

* Immunosuppressive medicines may be effective for the small percentage of patients with severe symptoms that cannot be controlled with any of the above treatments.

* TNF inhibitors suppress tumor necrosis factor (TNF), a protein involved in the body's inflammatory response.

* Exercise, when introduced gradually, may help improve joint function. Strengthening and range-of-motion exercises will maintain or improve joint function. For patients with spine pain or inflammation, exercises to stretch and extend the back can be particularly helpful in preventing long-term disability. Aquatic exercise also may be helpful.

Prognosis

Most people with reactive arthritis recover fully from the initial flare of symptoms and are able to return to regular activities 2 to 6 months after the first symptoms appear. In such cases, the symptoms of arthritis may last up to 12 months, although these are usually very mild and do not interfere with daily activities.

Approximately 20% of people with reactive arthritis will have chronic arthritis, which usually is mild. Studies show that between 15% and 50% of patients will develop symptoms again sometime after the initial flare has disappeared. It is possible that such relapses may be due to re-infection. Back pain and arthritis are the symptoms that most commonly reappear. A small percentage of patients will have chronic, severe arthritis that is difficult to control with treatment and may cause joint deformity.

Researchers continue to investigate the causes of reactive arthritis and study treatments for the condition.