Lyme disease

Encyclopedia of Alternative Medicine by Belinda Rowland

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Definition

Lyme disease is an infection transmitted by the bite of ticks carrying the spiral-shaped bacterium (spirochete) Borrelia burgdorferi (Bb). The disease was named for Old Lyme, Connecticut, the town where it was first diagnosed in 1975, after a puzzling outbreak of arthritis. The spiral-shaped bacterium was named for its discoverer, Willy Burgdorfer. The effects of this disease can be long-term and disabling, unless it is recognized and treated properly with antibiotics.

Description

Lyme disease is a vector-borne disease, which means it is delivered from one host to another. In this case, a tick bearing the Bb organism literally inserts it into a host's bloodstream when it bites the host to feed on its blood. It is important, however, to note that neither Bb nor Lyme disease can be transmitted from one person to another.

In the United States, Lyme disease accounts for more than 90% of all reported vector-borne illnesses. It is a significant public health problem and continues to be diagnosed in increasing numbers. More than 99,000 cases were reported between 1982 and 1996 in the United States. The number of new Lyme disease cases reached a record high in 1998 (16,801 cases), following a drop in reported cases from 1994 (13,043 cases) to 1995 (11,700 cases). Controversy clouds the true incidence of Lyme disease because no test is definitively diagnostic for the disease, and the broad spectrum of Lyme disease's symptoms mimic those of so many other diseases. Originally, public health specialists thought Lyme disease was limited geographically in the United States to the East Coast. We now know it occurs in most states, with the highest number of cases in the eastern third of the country.

The risk for acquiring Lyme disease varies, depending on what stage in its life cycle a tick has reached. A tick passes through three stages of development--larva, nymph, and adult--each of which is dependent on a live host for food. In the United States, Bb is borne by ticks of several species in the genus Ixodes, which usually feed on the white-footed mouse and deer (and are often called deer ticks). In the summer, the larval ticks hatch from eggs laid in the ground and feed by attaching themselves to small animals and birds. At this stage they are not a problem for humans. It is the next stage--the nymph--that causes most cases of Lyme disease. Nymphs are very active from spring through early summer, at the height of outdoor activity for most people. Because they are still quite small (less than 2 mm in length), they are difficult to spot, giving them ample opportunity to transmit Bb while feeding. Although far more adult ticks than nymphs carry Bb, the adult ticks are much larger, more easily noticed, and more likely to be removed before the 24 hours or more of continuous feeding needed to transmit Bb.

Causes & symptoms

Lyme disease is a collection of effects caused by Bb. Once Bb gains entry to the body through a tick bite, it can move through the bloodstream quickly. Only 12 hours after entering the bloodstream, Bb can be found in cerebrospinal fluid (which means it can affect the nervous system). Treating Lyme disease early and thoroughly is important because Bb can hide for long periods within the body in a clinically latent state. That ability explains why symptoms can recur in cycles and can flare up after months or years, even over decades. It is important to note, however, that not everyone exposed to Bb develops the disease.

Lyme disease is usually described in terms of length of infection (time since the person was bitten by a tick infected with Bb) and whether Bb is localized or disseminated (spread through the body by fluids and cells carrying Bb). Furthermore, when and how symptoms of Lyme disease appear can vary widely from patient to patient. People who experience recurrent bouts of symptoms over time are said to have chronic Lyme disease.

Early, localized Lyme disease

The most recognizable indicator of Lyme disease is a rash around the site of the tick bite. Often, the tick exposure has not been recognized. The area of rash eruption might be warm or itch. The rash--erythema migrans (EM)--generally develops within 3-30 days and usually begins as a round, red patch that expands. Clearing may take place from the center out, leaving a bull's-eye effect; in some cases, the center gets redder instead of clearing. The rash may look like a bruise on individuals with dark skin. Of those who develop Lyme disease, about 50% notice the rash; about 50% notice flu-like symptoms, including fatigue, headache, chills and fever, muscle and joint pain, and lymph node swelling. However, a rash at the site can also be an allergic reaction to the tick saliva rather than an indicator of Lyme disease, particularly if the rash appears in less than 3 days and disappears only days later.

Late, disseminated disease and chronic Lyme disease

Weeks, months, or even years after an untreated tick bite, symptoms can appear in several forms, including:

• fatigue, forgetfulness, confusion, mood swings, irritability, numbness
• neurologic problems, such as pain (unexplained and not triggered by an injury), Bell's palsy (facial paralysis, usually one-sided but may be on both sides), and a mimicking of the inflammation of brain membranes known as meningitis; (fever, severe headache, stiff neck)
• arthritis (short episodes of pain and swelling in joints) and other musculoskeletal complaints

Less common effects of Lyme disease are heart abnormalities (such as irregular rhythm or cardiac block) and eye abnormalities (such as swelling of the cornea, tissue, or eye muscles and nerves).

Diagnosis

A clear diagnosis of Lyme disease can be difficult, and relies on information the patient provides and the doctor's clinical judgment, particularly through elimination of other possible causes of the symptoms. Lyme disease may mimic other conditions, including chronic fatigue syndrome (CFS), multiple sclerosis (MS), and other diseases with many symptoms involving multiple body systems. Differential diagnosis (distinguishing Lyme disease from other diseases) is based on clinical evaluation with laboratory tests used for clarification, when necessary. A two-test approach is common to confirm the results. Because of the potential for misleading results (false-positive and false-negative), laboratory tests alone cannot establish the diagnosis.