Lyme Disease

Lyme disease is an infection transmitted by the bite of ticks carrying the spiral-shaped bacterium Borrelia burgdorferi. The disease was named for Lyme, Connecticut, the town where it was first diagnosed in 1975 after a puzzling outbreak of arthritis. The organism 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, which is also called Lyme borreliosis, is a vector-borne disease. This term means that it is delivered from one host to another. In this case, a tick bearing the Borrelia burgdorferi organism literally inserts it into a host's bloodstream when it bites the host to feed on its blood. It is important to note that neither Borrelia burgdorferi nor Lyme disease can be transmitted directly from one person to another, or from pets to humans.

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 significant numbers. More than 99,000 cases were reported between 1982 and 1996. When the numbers for 1996 Lyme disease cases reported were tallied, there were 16,455 new cases, a record high 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 and a strip along the West Coast that includes California and Oregon. As of 2001, Lyme disease is also found across Europe, in the countries of the former Soviet Union, and in China and Japan.

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, Borrelia burgdorferi 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), they are difficult to spot, giving them ample opportunity to transmit Borrelia burgdorferi while feeding. Although far more adult ticks than nymphs carry Borrelia burgdorferi, 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 Borrelia burgdorferi.

Causes and symptoms

Lyme disease is caused by Borrelia burgdorferi. Once Borrelia burgdorferi gains entry to the body through a tick bite, it can move through the bloodstream quickly. Only 12 hours after entering the bloodstream, Borrelia burgdorferi can be found in cerebrospinal fluid (which means it can affect the nervous system). Treating Lyme disease early and thoroughly is important because lyme disease 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,

The first sign of Lyme disease is usually an itchy rash around the site of the tick bite. (Science Photo Library. Custom Medical Stock Photo. Reproduced by permission.)

that not many people who are exposed to Borrelia burgdorferi 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 lyme disease) and whether Borrelia burgdorferi is localized or disseminated (spread through the body by fluids and cells carrying Borrelia burgdorferi). 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 eruption might be warm or itch. The rash—erythema migrans (EM) generally develops within three to 30 days and usually begins as a round, red patch that expands outward. About 75% of patients with Lyme disease develop EM. 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 people with dark skin. Of those who develop lyme disease, 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 three 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)
• arthritis (short episodes of pain and swelling in joints) and other musculoskeletal complaints. Arthritis eventually develops in about 60% of patients with untreated lyme disease

Lyme disease accounts for more than 90% of all reported vector-borne illnesses in the United States. It is caused by an infection transmitted by the bite of ticks carrying the Borrelia burgdorferi bacterium. Data taken from the Centers for Disease Control. Illustration by Electronic Illustrators Group.)

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 kyme 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.

In February 1999 the Food and Drug Administration (FDA) approved a new blood test for Lyme disease called PreVue. The test, which searches for antigens (substances that stimulate the production of antibodies) produced by Borrelia burgdorferi, gives results within one hour in the doctor's office. A positive result from the PreVue test is confirmed by a second blood test known as the Western blot, which must be done in a laboratory.

Doctors generally know which disease-causing organisms are common in their geographic area. The most helpful piece of information is whether a tick bite or rash was noticed and whether it happened locally or while traveling. Doctors may not consider Lyme disease if it is rare locally, but will take it into account if a patient mentions vacationing in an area where the disease is commonly found.

Treatment

The treatment for Lyme disease is antibiotic therapy; however, overprescribing of antibiotics can lead to serious problems, so the decision to treat must be made with care. Disease organisms can develop resistance to families of medications over time, rendering the drugs useless. Furthermore, testing and treatments can be expensive. If a patient has strong indications of Lyme disease (symptoms and medical history), the doctor will probably begin treatment on the presumption of this disease. The American College of Physicians recommends treatment for a patient with a rash resembling EM or who has arthritis, a history of an EM-type rash, and a previous tick bite.

The benefits of treating early must be weighed against the risks of over treatment. The longer a patient is ill with lyme disease before treatment, the longer the course of therapy must be, and the more aggressive the treatment. The development of opportunistic organisms may produce other symptoms. For example, after long-term antibiotic therapy, patients can become more susceptible to yeast infections. Treatment may also be associated with adverse drug reactions.

For most patients, oral antibiotics (doxycycline or amoxicillin) are prescribed for 21 days. When symptoms indicate nervous system involvement or a severe episode of Lyme disease, intravenous antibiotic (ceftriaxone) may be given for 14-30 days. Some physicians consider intravenous ceftriaxone the best therapy for any late manifestation of disease, but this is controversial. Corticosteroids (oral) may be prescribed if eye abnormalities occur, but they should not be used without first consulting an eye doctor.

The doctor may have to adjust the treatment regimen or change medications based on the patient's response. Treatment can be difficult because Borrelia burgdorferi comes in several strains (some may react to different antibiotics than others) and may even have the ability to switch forms during the course of infection. Also, Borrelia burgdorferi can shut itself up in cell niches, allowing it to hide from antibiotics. Finally, antibiotics can kill Borrelia burgdorferi only while it is active rather than dormant.

Alternative treatment

Supportive therapies may minimize symptoms of LD or improve the immune response. These include vitamin and nutritional supplements, mostly for chronic fatigue and increased susceptibility to infection. For example, yogurt and Lactobacillus acidophilus preparations help fight yeast infections, which are common in people on long-term antibiotic therapy. In addition, botanical medicine and homeopathy can be considered to help bring the body's systems back to a state of health and well being. A Western herb, spilanthes (Spilanthes spp.), may be effective in treating diseases like LD that are caused by spirochetes (spiral-shaped bacteria).

Prognosis

If aggressive antibiotic therapy is given early, and the patient cooperates fully and sticks to the medication schedule, recovery should be complete. Only a small percentage of lyme disease patients fail to respond or relapse (have recurring episodes). Most long-term effects of the disease result when diagnosis and treatment is delayed or missed. Co-infection with other infectious organisms spread by ticks in the same areas as Borrelia burgdorferi (babesiosis and ehrlichiosis, for instance) may be responsible for treatment failures or more severe symptoms. Lyme disease has been responsible for deaths, but they are rare.

Prevention

Get vaccinated

A vaccine against Lyme disease was approved by the FDA in 1999. The vaccine, called LYMErix, appears to work by stimulating the production of antibodies in human blood that kill Lyme disease spirochetes in the gut of the tick when the tick feeds on a vaccinated person. The vaccine is given in three doses over a one-year period; the first dose is followed by a second dose one month later, and a third dose a year after the first. The doses should be timed so that the second and third doses are given several weeks before the beginning of spring. It is not known how long the vaccine protects people against Lyme disease.

Household pets can get lyme disease and develop the same joint pains and fever as humans, but dogs at least can also be protected by vaccination. As of 1999, there are three lyme vaccines available for dogs, called LymeVax, Galaxy Lyme, and Canine Recombinant lyme. Healthy dogs nine weeks or older can be vaccinated. There is no vaccine available as yet for cats.

Although LYMErix protects most people, it is not 100% effective against Lyme disease. It should not be considered a substitute for other preventive measures. The best prevention strategy is through minimizing risk of exposure to ticks and using personal protection precautions.

Minimize risk of exposure

Precautions to avoid contact with ticks include moving leaves and brush away from living quarters. Most important are personal protection techniques when outdoors, such as:

• spraying tick repellent on clothing and exposed skin.
• wearing light-colored clothing to maximize ability to see ticks
• tucking pant legs into socks or boot top
• checking children and pets frequently for ticks

In highly tick-populated areas, each individual should be inspected at the end of the day to look for ticks.

Minimize risk of disease

The two most important factors are removing the tick quickly and carefully, and seeking a doctor's evaluation at the first sign of symptoms of Lyme disease. When in an area that may be tick-populated:

• check for ticks, particularly in the area of the groin, underarm, behind ears, and on the scalp
• stay calm and grasp the tick as near to the skin as possible, using a tweezer
• to minimize the risk of squeezing more bacteria into the bite, pull straight back steadily and slowly
• do not try to make the tick back out by using vaseline, alcohol, or a lit match
• place the tick in a closed container (for species identification later, should symptoms develop) or dispose of it by flushing
• see a physician for any sort of rash or patchy discoloration that appears three to 30 days after a tick bite

Medical studies to date do not support the preventative use of antibiotics after a tick bite, even if the tick has been identified as a deer tick. The risk of Lyme disease after a deer tick exposure appears to be quite low.