Reactive Arthritis (cont.)

What causes reactive arthritis?

As mentioned, reactive arthritis is felt in part to be genetic. There are certain genetic markers that are far more frequent in patients with reactive arthritis than in the normal population. For example, the HLA-B27 gene is commonly seen in patients with reactive arthritis. Even in patients who have the genetic background that predisposes them to developing reactive arthritis, however, exposure to certain infections seem to be required to trigger the onset of the disease.

Reactive arthritis can occur after venereal infections. The most common bacterium that has been associated with this post-venereal form of reactive arthritis is an organism called Chlamydia trachomatis. Reactive arthritis also occurs after infectious dysentery, with bacterial organisms in the bowel, such as salmonella, shigella, yersinia, and campylobacter. Typically, the arthritis develops one to three weeks after the onset of the bacterial infection.

What are symptoms of reactive arthritis?

The symptoms of reactive arthritis can be divided into those that affect the joints and those that affect the non-joint areas.

The classic joints that can become inflamed in reactive arthritis are the knees, ankles, feet, and wrists. The particular joints involved are usually asymmetric, that is, one side of the body or the other is affected, rather than both sides simultaneously. The inflammation leads to stiffness, pain, swelling, warmth, and redness of the joints involved. Patients may develop inflammation of entire fingers or toes which can give the appearance of a "sausage digit." This feature is also seen in patients with another type of arthritis called psoriatic arthritis that is associated with skin inflammation of psoriasis. The arthritis of reactive arthritis can be associated with inflammation of the spine, leading to stiffness and pain in the back or neck (characteristic of all of the spondyloarthropathies).

Cartilage can also become inflamed, especially around the breastbone where the ribs meet in the front of the chest, this condition is called costochondritis. Muscles attach to the bones by tendons. In reactive arthritis, the tendon insertion points can become inflamed (tendinitis), tender, and painful when exercised.

Non-joint areas that become inflamed and cause symptoms of pain and irritation in patients with reactive arthritis include the eyes, genitals, urinary tract (urethra, bladder and prostate gland), skin, mouth lining, large bowel, and the aorta.

Inflammation of the white portion of the eye (conjunctivitis) and the iris of the eye (iritis) is frequently seen early in reactive arthritis and may be intermittent. When the whites of the eye are inflamed causing conjunctivitis, there may be no pain. When the colored part of the eye (iris) is inflamed, causing iritis, it can be very painful and especially worse when looking into bright lights.

Urinary tract inflammation commonly involves the urethra, the tube that drains urine from the bladder. This inflammation (urethritis) can be associated with burning on urination and/or pus drainage from the end of the penis. The skin around the penis can become inflamed and peel. The bladder and prostate gland can also become inflamed, leading to an urge to urinate from cystitis and prostatitis respectively.

The skin of the palms of the hands and/or the soles of the feet can develop tiny fluid-filled blisters that sometimes are filled with old blood. The affected skin can peel and may mimic psoriasis. The classic appearance is medically referred to as keratoderma blennorrhagica.

The mouth can develop open sores (ulcerations) on the hard and soft palate, and even on the tongue. These may go unnoticed by the patient, as they are often painless. Inflammation of the large bowel (colitis) can cause diarrhea, or pus or blood in the stool. Inflammation of the aorta (aortitis) can be seen in a small percentage of patients who have reactive arthritis. It can lead to failure of the aortic valve of the heart, which can cause heart failure. The electrical conducting pathway of the heart can also become scarred in reactive arthritis, leading to irregular heartbeats (arrhythmias) that may require placement of a pacemaker to regulate the heartbeat.

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