Lyme Disease: Diagnosis, Treatment and Prevention

by Food and Drug Administration (FDA)

(Page 2 of 2)

The Importance of Proper Diagnosis

FDA's concern about the potential for misdiagnosing Lyme disease is based on results from commonly marketed blood tests used for detecting antibodies to the organism that causes infection. Antibodies in the patient's blood indicate that the body's immune system has detected invaders, but some tests cannot tell if those invaders are the Lyme disease bacteria. The test most often used to detect antibodies is called an enzyme-linked immunosorbent assay (ELISA) technique.

In addition, in February, FDA cleared a new blood test for Lyme disease that can be used in a doctor's office. PreVue B. burgdorferi Antibody Detection Assay, made by Chembio Diagnostic Systems, Medford, N.Y., is intended, like the ELISA test, to be used as the first step in testing people suspected of having Lyme disease. The PreVue test searches for antigens made by the B. burgdorferi bacterium that is responsible for the infection.

Unlike ELISA, which must be performed in a lab, PreVue provides results in one hour at the doctor's office. Understanding the limits of such testing, however, is important in diagnosing and treating the disease, says Sharon Hansen, Ph.D., a microbiologist with FDA's Center for Devices and Radiological Health. She advises that the tests be used only to support a clinical diagnosis of the disease, as in Chinnici's case, and not solely for making initial diagnostic or treatment decisions.

"In early diagnosis of Lyme disease these tests should not be used to rule in or rule out the infection," she advises, "especially in the absence of a rash." She explains that a positive test result does not conclusively indicate infection, and that people with active Lyme disease may get a negative result. She adds that when the ELISA test is positive, it must be followed and confirmed by a supplemental, second-step test known as the Western blot. The ability of Western blot to detect antibodies specific for B. burgdorferi, she concludes, reduces the number of false positives obtained with ELISA.

Like ELISA, positive results from PreVue also must be confirmed with a Western blot test done by a laboratory.

Treatment and Prevention

Most Lyme disease patients can be successfully treated with standard antibiotics. FDA approved Ceftin (cefuroxime axetil) Dec. 19, 1996, for the treatment of early Lyme disease. Recommended regimens of oral antibiotics can speed the healing of the rash, and can help prevent subsequent symptoms such as arthritis or neurological problems.

Hansen says that patients treated in the early stages with antibiotics usually recover rapidly and completely. Patients treated in later stages of the disease also may respond well to antibiotics, but in some cases, symptoms of persisting infection or inflammation may continue or recur, causing permanent damage.

"Lyme disease is a great masquerader," she says. "The bacteria may lay dormant and the symptoms disappear, but as the bacteria becomes active again, the symptoms will reappear." Hanson adds, "Even when the bacteria is eradicated from the body, the damage that has already been done may persist."

FDA, CDC, and the National Institutes of Health all agree that education is the most important part of Lyme disease prevention. Research has indicated that early removal of a tick can ward off much of the danger, but diagnosing the disease and treating infection remain difficult.

"I can't emphasize strongly enough the importance of finding a doctor who is experienced in recognizing this infection," adds Don C. "As in my case, where Lyme disease is concerned, time is of the essence."

Lyme History 101

The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, says a skin rash similar to that of Lyme disease was recognized in Europe and was described in medical literature dating back to the turn of the century. Researchers believe that the disease may have spread from Europe to the United States in the early 1900s. But it wasn't until the influx of suburban developments into rural areas where deer ticks are common, coupled with the exploding deer population, that the disease became prevalent, according to NIAID.

Lyme disease was first recognized in the United States in 1975 when a cluster of rheumatoid arthritis cases occurred in the town of Lyme, Conn. The victims were mostly children, and the outbreak began with rashes, headaches, and joint pains during the summer months — the height of tick season.

By 1994, 48 states and the District of Columbia had reported Lyme disease cases, although most were concentrated mainly in the coastal Northeast, the Mid-Atlantic states, Wisconsin and Minnesota, and northern California. Three years later, the national Centers for Disease Control and Prevention says, more cases of Lyme disease were reported than the combined total of cases reported for measles, mumps, rubella, whooping cough, cholera, tetanus, diphtheria, meningitis, and a host of other lesser known conditions.

But CDC also estimates that thousands of Lyme disease cases go undiagnosed, untreated and unreported, due in large part to the disease's uncanny ability to mimic other illnesses.

Preventing Infection

Most cases of Lyme disease occur in the spring and summer months when ticks in the nymph stage are feeding and people generally spend more time outdoors, often with more skin exposed. To minimize the risk of contracting Lyme disease, the national Centers for Disease Control and Prevention recommends the following precautions:

• Avoid areas where deer ticks live, such as wooded, brushy, and grassy places (including lawns and gardens), especially from May through August.
• Wear long pants and long-sleeved shirts when frequenting these areas to minimize skin exposure.
• Tuck pant legs into socks or boots to form a barrier to tick attachment.
• Tape the area where pants and socks meet so that ticks cannot crawl underneath.
• Wear light-colored clothing so that ticks can be spotted more easily.
• Spray insect repellent that contains DEET on exposed skin, other than the face, or treat clothing with permethrin, which kills ticks on contact. Use sparingly on children and avoid use on their faces and hands.
• Walk in the center of trails to avoid overhanging grass or brush.
• Shower after all outdoor activities. If a tick is still wandering, it may wash off.
• Check periodically for ticks if you've been in and around brushy areas or working in a garden, looking particularly for what may appear to be a speck of dirt.

Protecting Fido and Kitty

Household pets can get Lyme disease, too. Typical symptoms in animals include joint soreness and lameness, fever, and loss of appetite.

Currently three Lyme disease vaccines are available for dogs — LymeVax, Galaxy Lyme, and Canine Recombinant Lyme. Larry Elskin with the U.S. Department of Agriculture's Center for Biologics says that healthy dogs can be vaccinated when they are 9 weeks or older. (There is no vaccine available for cats.)

The American dog tick, which is more commonly found on pets, is much larger than the deer tick and, the national Centers for Disease Control and Prevention says, is not known to carry Lyme disease. Checking pets for all types of ticks before letting them enter the home reduces the risk of infection for both pet and owner.

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.