Lyme Disease Information

Lyme disease. named for the small Connecticut town where it was first recognized in 1975, affects multiple body systems. Persons of all ages and both sexes are affected, with onset during the summer months. It occurs in areas where the geographic ranges of certain ixodid ticks are located. It typically begins with the classic skin lesion called erythema chronicum migrans. Weeks or months later, cardiac, neurologic, or joint abnormalities develop, possibly followed by arthritis.

Lyme disease is the leading tick-borne disease in the United States, with more than 16,000 cases reported to the CDC in 1999, but it is not the only disease carried by deer ticks. Two other diseases, human granulocytic ehrlichiosis (HGE) and babesiosis, are also transmitted through deer tick bites.

Causes

Lyme disease is caused by the spirochete Borrelia burgdorferi. Carried by the minute tick Ixodes dammini (or another tick in the Ixodidae family), the disease occurs when a tick injects spirochete-laden saliva into the bloodstream or deposits fecal matter on the skin, After incubating for 3 to 32 days. the spirochetes migrate outward on the skin, causing a rash and disseminating to other skin sites or organs by the bloodstream or lymph system. The spirochete's life cycle isn't completely understood: They may survive for years in the joints. or they may die after triggering an inflammatory response in the host.

Signs and symptoms

One sign of Lyme disease is a rash, which may appear 3 to 30 days after a tick bite. This rash, called erythema migrans (say: "ear-a-theem-a my-granz"), usually starts at the site of the tick bite. It may begin as a small red spot and grow larger. The center may fade, creating a "bull's eye" or ring appearance, but this is not always the case. Some people with Lyme disease have many red spots. The rash may burn, hurt or itch, or you may not feel it.

Other symptoms of Lyme disease include fever, chills, headaches, stiff neck, fatigue, muscle aches and joint pain. In a few people, early Lyme disease can spread to the heart or the nervous system. If Lyme disease spreads to the heart, the person may feel an irregular or slow heartbeat. Early spread of Lyme disease to the nervous system can cause the face to droop (a condition called Bell's palsy).

Diagnostic tests

Blood tests, including antibody titers to identify B. burgdorferi, are the most practical diagnostic tests. The enzyme-linked immunosorbent assay (ELISA) may be ordered because of its greater sensitivity and specificity. However, serologic test results don't always confirm the diagnosis - especially in Lyme disease's early stages before the body produces antibodies - or seropositivity for B. burgdorferi. Also, the validity of test results depends on laboratory techniques and interpretation.

Mild anemia in addition to elevated erythrocyte sedimentation rate, white blood cell count, serum immunoglobulin M levels: and aspartate aminotransferase levels support the diagnosis.

A lumbar puncture may be ordered if Lyme disease involves the central nervous system. Analysis of cere­brospinal fluid may detect antibodies to B. burgdorferi.

Treatment

A 10- to 20-day course of antibiotics is the treatment of choice. Adults typically receive doxycycline; amoxicillin, cefuroxime axetil, and erythromycin are alternatives. Children usually receive oral amoxicillin. Administered early in the disease, these medications car minimize later complications. In later stages, high-dose ceftriaxone, cefotaxime, or penicillin G sodium administered I.V. may produce good results.

Prevention

When walking or hiking in wooded or grassy areas, tuck long pants into socks to protect the legs, and wear shoes and long-sleeved shirts. Ticks will show up on white or light colors better than dark colors, making them easier to remove from your clothing. Spray your clothes with insect repellant.

Check yourself and your pets frequently. If you find ticks, remove them immediately by using tweezers, pulling carefully and steadily.

Ticks can be fairly large -- about the size of a pencil eraser -- or so small that they are almost impossible to see. After returning home, remove your clothes and thoroughly inspect all skin surface areas, including your scalp. Ticks can quickly climb up the length of your body. Some ticks are large and easy to locate. Other ticks can be quite small, so carefully evaluate all spots on the skin.