LYME DISEASE


DEFINITION

Lyme disease is caused by the bacterium Borrelia burgdorferi (Bb). The bacterium is carried by ticks and is transmitted to humans through a tick bite. The disease is named for the town of Lyme, Connecticut. It was in Lyme that the disease was first discovered in 1975, after a series of unexplained cases of arthritis developed.

Lyme Disease: Words to Know

Cerebrospinal fluid (CSF):
Fluid found around the brain and spinal cord. CSF provides nutrients to the cells of the nervous system and provides a cushion for the structures of the nervous system.
Larva:
An immature form of an organism.
Latency:
A period during which a diseasecausing organism is inactive but not dead.
Nymph:
A stage of development between the most immature and the adult stages of life.
Vector-borne disease:
A disease transferred from one organism to another by means of a third organism, such as an insect or tick.

DESCRIPTION

Lyme disease is a vector-borne disease. A vector is an organism that carries a disease from one organism to another. In this case, the vector is the tick. The tick carries the bacterium B. burgdorferi in its blood and saliva. When the tick bites a human, it leaves some of its saliva, along with the bacterium, in the human's bloodstream. The bacterium begins to reproduce and spread. Eventually it causes the symptoms of Lyme disease.

Lyme disease accounts for about 90 percent of all reported vector-borne diseases in the United States. Nearly one hundred thousand cases of the disease were reported between 1982 and 1996. The true number of cases is difficult to estimate accurately. Some experts think that there are many more cases of the disease than are actually reported.

CAUSES

A tick passes through three stages of development: larva, nymph, and adult. The larva is an immature form of the tick. It hatches from eggs laid on the ground in summer. Larvae attach themselves to small animals and birds and feed on their blood. At this point, the larvae are no threat to humans.

Eventually, larvae develop into nymphs. Nymphs feed off humans. It is at this stage of a tick's life that it is the greatest threat. A nymph can transmit Lyme disease if it bites a human. A nymph is too small to be seen easily seen, and as a result, people may be bitten without realizing it.

The first sign of Lyme disease is usually a rash around the site of the tick bite. It may be warm or itchy. (© 1993 Science Photo Library. Reproduced by permission of Custom Medical Stock Photo.)
The first sign of Lyme disease is usually a rash around the site of the tick bite. It may be warm or itchy. (© 1993
Science Photo Library
. Reproduced by permission of
Custom Medical Stock Photo
.)

Adult ticks feed off humans, mice, and deer. They are sometimes called deer ticks. They can still transmit Lyme disease, but they are larger and easier to see. They are thus less of a threat to humans, who can pick them off quite easily.

The Bb bacterium spreads quickly once it reaches the human bloodstream. It can usually be found in the cerebrospinal fluid (CSF) only twelve hours after a tick bite. Cerebrospinal fluid is the fluid found in the spinal column.

SYMPTOMS

The way symptoms develop following a tick bite varies widely among individuals. Some people have no symptoms at all. Others have a serious attack

Magnification of a mature deer tick, a carrier for Lyme disease. (Reproduced by permission of CNRI/Phototake NYC)
Magnification of a mature deer tick, a carrier for Lyme disease. (Reproduced by permission of
CNRI/Phototake NYC
)

that appears quickly and then disappears. Still others develop a chronic (long-lasting) form of the disease.

One factor that complicates the symptoms of Lyme disease is the latency of the bacterium. Latency means that the bacterium can become inactive for long periods of time. It has not died, but it does not cause any symptoms. Then, at some later date, the bacterium becomes active again and symptoms reappear.

Early, Localized Lyme Disease

The first sign of Lyme disease is usually a rash around the site of the tick bite. It may be warm or itchy. In many cases, the patient may not even notice the rash. Over the next three to thirty days, the rash expands. The center of the rash may clear up, forming a bull's-eye pattern. Or the center may become red.

Other early symptoms of a Lyme infection include headache, fever, chills, fatigue, muscle and joint pain, and swelling of the lymph nodes.

Late, Chronic Lyme Disease

Many cases of Lyme disease go unnoticed and untreated. In such cases, new symptoms may appear a few weeks, months, or even years after the tick bite. These symptoms include:

  • Fatigue, forgetfulness, confusion, changes in mood, irritability, and numbness
  • Disorders of the nervous system, such as unexplained pain and paralysis of the facial muscles
  • Arthritis and other problems with muscles and bones

DIAGNOSIS

One problem in diagnosing Lyme disease is that its symptoms are similar to other disorders. The first task facing a doctor is to eliminate other possible explanations for a patient's symptoms. The doctor will perform tests to ensure that the patient does not have chronic fatigue syndrome (see chronic fatigue syndrome entry), multiple sclerosis (see multiple sclerosis entry), or some other disease with symptoms similar to those of Lyme disease.

An important aid in diagnosing Lyme disease is a geographical factor. Currently, Lyme disease occurs much more frequently in some parts of the United States than in others. The disease is quite rare in the Rocky Mountain states, for example, but relatively common in the Northeastern states. A doctor is aided in making a diagnosis if he or she can find out what part of the country the patient was in when he or she was bitten by a tick.

TREATMENT

Lyme disease is caused by a bacterium, so it can be treated with antibiotics. In general, the earlier treatment begins, the greater the chance of success. The deciding factor is often the appearance of the characteristic rash. The usual treatment is an oral antibiotic, such as doxycycline (pronounced dok-si-SIE-kleen) or amoxicillin (pronounced uh-MOK-sih-SIL-in), given for twenty-one days.

Some doctors are cautious about the use of antibiotics with Lyme disease. In many instances, doctor prescribe antibiotics for ailments when they are really not needed. The problem with this practice is that bacteria may become resistant to antibiotics and are no longer killed by drugs that were once effective. Some doctors therefore wait until they are certain that a patient has Lyme disease before prescribing an antibiotic.

Alternative Treatment

A common goal of alternative treatments for Lyme disease is to strengthen overall body health. Practitioners may recommend vitamin and nutritional supplements for this purpose. In addition, some herbs are thought to be effective in treating bacterial diseases like Lyme disease. A popular choice for this purpose is the western herb spilanthes.

PROGNOSIS

The vast majority of patients who receive early treatment recover completely from Lyme disease. The key is that patients remain on the prescribed course of medication as directed by the doctor. Stopping medication too soon can cause relapses and reoccurrence of the disease.

A very small number of patients do not respond well to treatment. In the worst cases, people have died of the disorder. However, this is rare.

A NEW LYME DISEASE VACCINE

The U.S. Food and Drug Administration (FDA) has given its approval to a new Lyme disease vaccine. The approval for the vaccine, which is being manufactured by the U.S. pharmaceutical company SmithKline Beecham, came on December 21, 1998. The vaccine was one of two new products being tested. The other vaccine was being tested by the French firm of Pasteur Merieux Connaught.

Some authorities have questioned whether a vaccine for Lyme disease is really needed. They point out that the disease can be diagnosed and treated quite easily. Members of the Lyme Disease Foundation have argued, however, that the vaccine will bring relief to countless people who may be exposed to the disease.

PREVENTION

Researchers are currently testing vaccines against Lyme disease. Until they are approved, the best way to prevent Lyme disease is to avoid contact with ticks that carry Bb. Some general recommendations for people who spend time outdoors include:

  • Use bug repellents containing the chemical DEET.
  • Wear light-colored clothing in order to see ticks better.
  • Tuck pant legs into socks or boot tops.
  • Check children and oneself frequently for ticks.

Tick removal is an important step in avoiding infection. Some hints about tick removal include:

  • Using tweezers, grasp the tick as near to the skin as possible.
  • Pull the tick straight back steadily and slowly.
  • Do not try to make the tick back out by using petroleum jelly, alcohol, or a lit match.
  • Place the tick in a closed container or flush it down the toilet.
  • See a doctor if any sort of rash appears three to thirty days after the tick bite.

FOR MORE INFORMATION

Books

Territo, J., and D. V. Lang. Coping with Lyme Disease: A Practical Guide to Dealing with Diagnosis and Treatment. New York: Henry Holt, 1997.

Vanderhoof-Forschne, K. Everything You Need to Know about Lyme Disease and Other Tick-Borne Disorders. New York: John Wiley & Sons, 1997.

Organizations

Lyme Disease Foundation, Inc. One Financial Plaza, 18th Floor, Hartford, CT, (800) 886-LYME. http://www.lyme.org.

The Lyme Disease Network of New Jersey, Inc., 43 Winton Road, East Brunswick, NJ 08816. http://www.lymenet.org.