Getting Lyme Disease to Take a Hike

by Food and Drug Administration (FDA)

Now that summer is here, many people are hitting the hiking trail. But before you head for the wilds, you should take some special precautions, especially if you live in a part of the country where Lyme disease is prevalent.

It's been nearly two decades since medical detectives discovered that an outbreak of what looked like juvenile rheumatoid arthritis in Lyme, Conn., was actually a spirochetal (bacterial) infection spread by tick bite. Today we know enough about the tick and its infective cargo to avoid Lyme disease or stem its effects early. FDA regulates several products used to help diagnose and to treat this complex illness, but doctors sometimes still have a hard time diagnosing it.

Three Stages

Although most people can recall the tick bite that transmitted the bacteria responsible for their Lyme disease, 1 of 3 cannot remember being bitten. This is not surprising, because the responsible tick (of species Ixodes dammini or Ixodes pacificus) is as small as a poppy seed. It is often not seen or felt. If the tick stays attached and maintains contact with a person's blood for at least six hours, bacteria called Borrelia burgdorferi can travel from the tick's gut to the person's bloodstream. These bacteria are of a type called spirochetes, named after their spiral shape.

The bacteria soon migrate to specific areas of the body where they later may produce symptoms: within the skin at the bite site, in the synovial fluid of the joints where bones meet, and into nerve tissue.

The first sign of disease, in up to 80 percent of cases, is a distinctive large, red rash called erythema chronicum migrans, appearing at the site of the bite three to 30 days after contact. The lesion expands and may develop a clear area in the center, like a bulls-eye. Then, flu-like symptoms may set in, including headache, muscle ache, fatigue, and joint pain. If a physician suspects Lyme disease at this point — based on symptoms, the characteristic rash, the geographic area, and recollection of a tick bite — the patient may begin a course of antibiotic drugs that can stem further symptoms. With antibiotics, the rash usually clears up in a few days; otherwise, it disappears in about a month.

The second stage of Lyme disease occurs a few weeks or months following the tick bite, as bacteria spread beyond the skin. The body starts to produce antibodies against the bacteria, which, when detected in a person's blood, indicate exposure and form the basis of a tentative diagnosis. At this point, Lyme disease can be distinguished from other conditions, such as fibromyalgia (muscle pain) and chronic fatigue syndrome, which produce similar symptoms.

In this stage, 50 to 80 percent of patients develop arthritis. Lyme arthritis differs from rheumatoid arthritis in that it tends to come and go and affects two or three joints, rather than producing an all-over achiness. And while osteoarthritis can affect only a few joints, the presence of the other symptoms may suggest Lyme disease. New skin outbreaks, usually smaller than the first, may appear at this time.

The Borrelia bacteria can affect the nervous system in the second stage of Lyme disease. The brain, its membranes, or peripheral nerves may become inflamed, producing severe headache and a stiff neck. Inflammation of the cranial nerves may cause facial paralysis, lasting weeks or months. There may also be memory loss, difficulty concentrating, and changes in mood or sleep habits. About 15 percent of people with Lyme disease not given antibiotics in the first stage go on to develop nervous system symptoms.

About 8 percent of untreated Lyme patients develop heart problems, such as heart block, inflammation of the heart or surrounding tissue, and irregular heartbeat. These problems may produce symptoms of shortness of breath and dizziness.

The third stage of Lyme disease occurs about six months after the initial rash. Arthritis persists in about 50 percent of untreated patients, and may cause extreme swelling, particularly of the knee. In most patients, the arthritis eventually clears up. Only 5 to 10 percent are left with the continuous joint pain of chronic Lyme arthritis. Some evidence suggests that these people are genetically predisposed to overreact to the Lyme bacterium, extending the normal inflammatory response to infection or injury.

Late-stage Lyme disease may also produce continued neurological symptoms and rash.

Hot Spots

More than 40,000 cases of Lyme disease in 48 states have been reported to the national Centers for Disease Control and Prevention since surveillance began in 1982. The disease, however, is still concentrated in certain areas where Lyme spirochetes, ticks, mice, and deer are common.

Each year, the geographic areas where spirochete-infected animals and Lyme disease occur enlarge. In the 1970s, in New England the illness was restricted to Cape Cod, Nantucket, Martha's Vineyard, and the southwest corner of Connecticut. Today, it is found in many parts of Connecticut, western Massachusetts, New Hampshire, and Maine. On the East Coast, one is most likely to contract Lyme disease on Block Island in Rhode Island, Martha's Vineyard and Nantucket Island in Massachusetts, eastern Long Island and Westchester County in New York, and in Connecticut, where epidemiologists identified the first cases. The illness is also common in wooded areas of the mid-Atlantic states, and in Wisconsin, Minnesota, and northern California.

The bacteria that cause Lyme disease have also spread up the Hudson River from Westchester, with the first cases identified in Adirondack State Park in upstate New York last summer. Lyme disease has been reported in all states except Alaska and Montana. However, the number of reported cases may be an overestimate, because other conditions associated with rash and joint pain may be incorrectly diagnosed as Lyme disease.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.