LYME DISEASE

What is Lyme Disease? In the early 1970s, a mysterious clustering of arthritis cases occurred among children in Lyme, Connecticut, and surrounding towns. Medical researchers soon recognized the illness as a distinct disease, which they called Lyme disease. They subsequently described the clinical features of Lyme disease, established the usefulness of antibiotic therapy in its treatment, identified the deer tick as the key to its spread, and isolated the bacterium that caused it.

What Causes Lyme Disease?

Investigations revealed that Lyme disease is caused by the bacterium, Borrelia burgdorferi. These bacteria are transmitted to humans by the bite of infected deer ticks and black-legged ticks.

After several months of being infected by B. burgdorferi, slightly more than half of those people not treated with antibiotics develop recurrent attacks of painful and swollen joints that last a few days to a few months. The arthritis can shift from one joint to another; the knee is most commonly affected. About 10 to 20 percent of untreated patients will go on to develop chronic arthritis.

What are the Symptoms of Lyme Disease?

Erythema Migrans - In most people, the first symptom of Lyme disease is a red rash known as erythema migrans (EM). The telltale rash starts as a small red spot at the site of the tick bite.

The spot expands over a period of days or weeks, forming a circular or oval shaped rash. Sometimes the rash resembles a bull's eye, appearing as a red ring surrounding a clear area with a red center. The rash, which can range in size from that of a dime to the entire width of a person's back, appears within a few weeks of a tick bite and usually occurs at the site of a bite. As infection spreads, rashes can appear at different sites on the body.

Erythema migrans is often accompanied by symptoms such as fever, headache, stiff neck, body aches, and fatigue. Although these flu-like symptoms may resemble those of common viral infections, Lyme disease symptoms tend to persist or may occur intermittently.

Lyme disease can also affect the nervous system, causing symptoms such as stiff neck and severe headache (meningitis), temporary paralysis of facial muscles (Bell's palsy), numbness, pain or weakness in the limbs, or poor motor coordination. More subtle changes such as memory loss, difficulty with concentration, and a change in mood or sleeping habits have also been associated with Lyme disease.

How Lyme Disease Is Diagnosed?

Lyme disease may be difficult to diagnose because many of its symptoms mimic those of other disorders. In addition, the only distinctive hallmark unique to Lyme disease-the erythema migrans rash-is absent in at least one-fourth of the people who become infected. The results of recent studies indicate that an infected tick must be attached to a person's skin for at least 2 days to transmit the Lyme bacteria.

Although a tick bite is an important clue for diagnosis, many patients cannot recall having been bitten recently by a tick. This is not surprising because the tick is tiny, and a tick bite is usually painless.

When a patient with possible Lyme disease symptoms does not develop the distinctive rash, a physician will rely on a detailed medical history and a careful physical examination for essential clues to diagnosis, with laboratory tests playing a supportive role.

How Lyme Disease Is Treated?

Nearly all Lyme disease patients can be effectively treated with an appropriate course of antibiotic therapy. In general, the sooner such therapy is begun following infection, the quicker and more complete the recovery.

Antibiotics, such as doxycycline, cefuroxime axetil, or amoxicillin taken orally for a few weeks, can speed the healing of the erythema migrans rash and usually prevent subsequent symptoms such as arthritis or neurological problems. Doxycycline will also effectively treat most other tick-borne diseases.

Patients younger than 9 years or pregnant or lactating women with Lyme disease are treated with amoxicillin, cefuroxime axetil, or penicillin because doxycycline can stain the permanent teeth developing in young children or unborn babies. Patients allergic to penicillin are given erythromycin.

Lyme disease patients with neurological symptoms are usually treated with the antibiotic ceftriaxone given intravenously once a day for a month or less. Most patients experience full recovery.

Who Is At Risk?

In the United States, Lyme disease is mostly localized to states in the northeastern, mid-Atlantic, and upper north-central regions, and to several counties in northwestern California.

Individuals who live or work in residential areas surrounded by tick-infested woods or overgrown brush are at risk of getting Lyme disease. Persons who work or play in their yard, participate in recreational activities away from home such as hiking, camping, fishing and hunting, or engage in outdoor occupations, such as landscaping, brush clearing, forestry, and wildlife and parks management in endemic areas may also be at risk of getting Lyme disease.

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