Types of Arthritis: Spondyloarthropathies, Lyme Disease

by Food and Drug Administration (FDA)

(Page 4 of 4)

Spondyloarthropathies

The spondyloarthropathies are a collection of disorders that tend to affect the spine and include: Reiter's syndrome, psoriatic arthritis, intestinal arthropathy, juvenile ankylosing spondylitis, reactive arthropathy, and the most common type, ankylosing spondylitis, in which the spinal bones fuse. Of the 2.5 million people with these ailments in this country, 75 percent are male.

This particular form of arthritis has been under intense scrutiny since 1973, when researchers in the United States and Great Britain found that 90 percent of patients with ankylosing spondylitis have a protein on their cell surfaces called HLA-B27. The HLA proteins are controlled by a group of genes that oversees immune system function. The HLA protein so common among those with ankylosing spondylitis is found in only 7 percent of the general population, suggesting that there might be a link between HLA-B27 and the arthritis. HLA-B27 is also found in the other spondyloarthropathies to a greater extent than is seen in the general population.

Although the nature of the link between HLA-B27 and the spondyloarthropathies is still elusive, researchers at the Harold C. Simmons Arthritis Research Center at the University of Texas Southwest Medical Center in Dallas recently came a giant step closer to explaining it by introducing into rats through genetic engineering the human HLA-B27 gene. The rats developed symptoms remarkably like their human counterparts — persistent diarrhea, skin and hair scaliness, and joint inflammation. The rats with arthritis in their genes will be raised in a germ-free environment from birth. If they fail to develop symptoms, it will mean that an environmental trigger is required to start the disease process.

Commenting on this research, James O. Mason, M.D., assistant secretary for health in the U.S. Department of Health and Human Services, says, "This important work, which could only be performed in animals, holds great promise for helping us to better diagnose and treat these diseases in humans."

Lyme Disease

Bacterial infection was added to the list of causes behind arthritis in 1974, when 30 neighbors in the rural town of Lyme, Conn., came down with a baffling illness. It began with flu-like symptoms and a rash resembling a bull's-eye. This would happen 3 to 32 days following a tick bite, although the person might be unaware of the bite. A few weeks after the initial symptoms, about half of the people developed joint, tendon, muscle, and bone pain, without swelling. In a few, swelling developed, mimicking juvenile rheumatoid arthritis or rheumatoid arthritis. The first clue that the illness was not juvenile rheumatoid arthritis was that the cases appeared in clusters. In Lyme and two neighboring towns, 39 youngsters and 12 adults, in a population of 12,000, had the mysterious illness. Normally, juvenile rheumatoid arthritis affects only 1 in 100,000 children. If the illness was juvenile rheumatoid arthritis, the incidence in this area would be 100 times greater than normal. In heavily wooded areas, the incidence was even more striking — 1 in 10 children, or 10,000 times greater than normal.

The people with what would become identified as Lyme disease were brought to the attention of Allen Steere, M.D., then a rheumatologist at Yale University in New Haven, Conn., and now affiliated with New England Medical Center in Boston. He eventually put together the pieces to find the culprit — a tick. "The initial challenge was to evaluate the clusters of children and adults in Lyme with the unusual form of arthritis. What suggested that it was arthropod- [tick] transmitted was the rural setting, the onset in early summer through fall, and the fact that multiple family members were affected yet had onset of symptoms in different years," Steere recalls.

Today we know that Lyme disease is actually caused by a spiral-shaped bacterium (spirochete) harbored in the deer tick, which spends part of its life cycle in mice and deer. Since its identification, the locations and the number of cases of Lyme disease have continued to increase. In 1983, 48 cases were reported to the national Centers for Disease Control in Atlanta, and by 1986, the number had risen to 439. In 1989, 7,400 cases were reported in 46 states, a 15-fold increase over the incidence in 1982, when national surveillance began.

Antibiotics administered promptly can halt the course of Lyme disease. With later disease and involvement of the heart, brain or joints, antibiotic therapy is not as effective. Once arthritis appears, the joint pain and stiffness can come and go, recurring even years later. Ten percent of those with Lyme disease arthritis are left with permanently stiffened joints. Researchers are optimistic that understanding how joints are affected by Lyme disease may have wide-ranging benefits. "We're hoping that the lessons we learn from Lyme disease will provide helpful clues in studying other types of arthritis," says Steere.

About the Author

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