How Lyme disease is Caused?

Lyme disease is a bacterial illness caused by a bacterium called a "spirochete." In the United States, the actual name of the bacterium is Borrelia burgdorferi. In Europe, another bacterium, Borrelia afzelii, also causes Lyme disease. Certain ticks found on deer harbor the bacterium in their stomachs.

Lyme disease is spread by these ticks when they bite the skin, which permits the bacterium to infect the body. Lyme disease is not contagious from an affected person to someone else. Lyme disease can cause abnormalities in the skin, joints, heart, and nervous system.

Key symptoms and signs of Lyme disease?

Lyme disease affects different areas of the body in varying degrees as it progresses. The site where the tick bites the body is where the bacteria enter through the skin. As the bacteria spread in the skin away from the initial tick bite, the infection causes an expanding reddish rash that is often associated with "flu-like" symptoms. Later, it can produce abnormalities in the joints, heart, and nervous system.

Lyme disease is medically described in three phases as: (1) early localized disease with skin inflammation; (2) early disseminated disease with heart and nervous system involvement, including palsies and meningitis; and (3) late disease featuring motor and sensory nerve damage and brain inflammation as well as arthritis.

In the early phase of the illness, within days to weeks of the tick bite, the skin around the bite develops an expanding ring of unraised redness. There may be an outer ring of brighter redness and a central area of clearing, leading to a "bull's-eye" appearance. This classic initial rash is called "erythema migrans" (formerly called erythema chronicum migrans).

Patients often can't recall the tick bite (the ticks can be as small as the periods in this paragraph). Also, they may not have the identifying rash to signal the doctor. More than one in four patients never even develop a rash. The redness of the skin is often accompanied by generalized fatigue, muscle and joint stiffness, swollen lymph nodes ("swollen glands"), and headache, resembling symptoms of a virus infection.

The redness resolves, without treatment, in about a month. Weeks to months after the initial redness of the skin the bacteria and their effects spread throughout the body. Subsequently, disease in the joints, heart, and nervous system can occur.

The later phases of Lyme disease can affect the heart, causing inflammation of the heart muscle. This can result in abnormal heart rhythms and heart failure. The nervous system can develop facial muscle paralysis (Bell's palsy), abnormal sensation due to disease of peripheral nerves (peripheral neuropathy), meningitis, and confusion. Arthritis, or inflammation in the joints, begins with swelling, stiffness, and pain. Usually, only one or a few joints become affected, most commonly the knees. The arthritis of Lyme disease can look like many other types of inflammatory arthritis and can become chronic.

Researchers have also found that anxiety and depression occur with an increased rate in people with Lyme disease. This is another important aspect of the evaluation and management of this condition.