Rheumatoid arthritis (RA) is a chronic inflammatory disease that causes pain, stiffness, and swelling around the joints. RA is often confused with osteoarthritis, which is a condition of wear and tear on the joints.

RA is not a condition of wear and tear that occurs with aging or injury. It is a disease known as an "autoimmune" disease in which your own immune system mistakenly attacks healthy tissue, causing inflammation that damages your joints. Normally, the immune system fights against infections and keeps a person's body healthy. However, in the case of RA, the immune system attacks cells in the joints, causing pain and swelling. Over time, people with RA often find that their joints are stiff and do not move properly, causing them considerable pain and discomfort.

	Proteus mirabilis is a bacterium that is often found in soil, water, and the intestinal tract of many mammals, including humans.

WHAT CAUSES RHEUMATOID ARTHRITIS (RA)?
Scientists and doctors do not know why people develop rheumatoid arthritis (RA). However, researchers are learning more every day. The latest scientific findings suggest that RA may be caused by a combination of genetic, environmental, or hormonal factors.

Genetic Factors: One interesting theory is that the tendency to develop RA is genetic, which means that it runs in families. In one study of identical twins, when one twin has RA, up to 30% of the second twins will develop RA in the future. Researchers have found that the tendency to develop RA is related to specific genes. However, not all people who have these genes will develop RA, and people who do not have these genes can still develop the condition. These findings suggest that other factors also play an important role in the development of RA.

Environmental Factors: Another theory is that RA is caused by environmental factors, such as exposure to bacteria or a particular diet that may occur naturally in certain locations. For example, some scientists have found that patients with RA are more likely than those without it to have been exposed to a bacterium called Proteus mirabilis. Other bacterial or viral infections also may trigger RA.

Researchers also have discovered that some autoimmune diseases, like RA, are more common in certain areas of the world. For example, scientists have suggested that environmental factors, such as not being able to get enough vitamin D, may be part of the reason that people living in Scandinavian countries are more likely to develop diabetes and arthritis. While theories such as this warrant further research, the cause of RA remains unknown.

Hormonal Factors: A third theory is that RA may be affected by hormones. Researchers have found that hormones, like estrogen and progesterone, increase during pregnancy but decrease afterward. This may explain why onset of RA often occurs following child birth or why women with RA who become pregnant often experience significant symptom improvement during pregnancy but have flare ups of RA once they have given birth.

	Symmetrical swelling is often associated with RA (e.g., both hands, both elbows, etc.).

RECOGNIZING THE SYMPTOMS
There are a few simple things that people can do to see if they might have rheumatoid arthritis (RA). However, to get an early diagnosis, it is important to talk to a rheumatologist, a physician who specializes in the treatment of arthritis. A primary care physician can provide a referral to a rheumatologist.

People with RA have joints that are tender, warm, and swollen. This occurs in a "symmetrical" pattern, meaning that if the left knee is affected, the right knee also is affected. RA often affects the wrist and finger joints closest to the hand, but neck, shoulders, elbows, hips, knees, ankles, and feet also may be affected. Other symptoms include pain or stiffness lasting for more than 30 minutes in the morning or after long rest and lack of activity. Patients with RA also may experience fatigue, an occasional fever, or a general sense of not feeling well.



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