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Key Points:

  • Lyme disease is the most common vector-borne disease in the United States, with cases reported from every state except Montana, Hawaii, and Oklahoma.

  • Most cases of Lyme disease are transmitted by deer ticks; in the south, however, a slightly different “Lyme disease” may be transmitted by the Lone Star tick.

  • It takes more than 24 hours for a feeding tick to transmit infection, and 3 to 5 days for the typical expanding bull's-eye rash to develop after the bite.

  • A single 200-mg dose of doxycycline, taken within 72 hours of the time of the bite, can prevent infection.

  • The diagnosis of Lyme disease is most commonly made on the characteristic expanding erythema migrans rash that occurs at the site of the tick bite.

  • The next most common presentation is with systemic, flu-like symptoms (fever, myalgias, headache, fatigue) but no rash.

  • Headache, neck stiffness, and thrombocytopenia (low platelets), should arouse suspicion of Lyme disease.

  • Treatment may require 2 to 4 weeks, or more, of antibiotics.

  • Signs and symptoms of Lyme disease may be mistaken for another illness. Untreated illness may result in chronic, disabling health problems.

What's New

Some Lyme disease experts (here) question treating "chronic Lyme disease" with antibiotics. Others argue that alternative diagnoses, such as anaplasma, babesia, bartonella, and ehrlichia, must first be excluded before advocating against antibiotic treatment for post tick-bite symptoms.

The Pattern of Lyme Disease

Lyme disease is a potentially serious illness that occurs worldwide. The disease was first recognized in the United States in 1975, following an investigation of a group of children with arthritis in Lyme, Connecticut. Lyme disease is now the most common vector-borne illness in the United States. In 2002, nearly 24,000 cases were reported, but the true number is probably higher. In the United States, 90% of cases are reported from nine states—Connecticut, Delaware, Maryland, New Jersey, New York, Pennsylvania, Rhode Island, Wisconsin, and Minnesota. In Canada, the disease is concentrated in Ontario and Manitoba.

Overseas Most cases are reported from Europe (especially Germany's Black Forest region, southern Sweden, southern and eastern Austria, and the northern Swiss plateau), the former Soviet Union (from the Baltics to the Pacific), China, Japan, and Australia. The incidence of Lyme disease in Latin America appears to be very low. In Africa, cases have been reported from Nigeria, Angola, Kenya, Tanzania, and Zambia. Antarctica is apparently free of the disease.

Different Types of Lyme Disease in the United States

Lyme disease occurring in the Northeast, the upper Midwest, and the Pacific states is caused primarily by the spirochete Borrelia burgdorferi, and is transmitted by deer ticks. Southern tick-associated rash illness (STARI) is a Lyme disease—like infection described in patients in the southeastern and south-central United States, whereas classic Lyme disease is relatively rare. STARI develops following the bite of a Lone Star tick (Amblyomma americanum) and is believed to be caused by infection with a spirochete tentatively named Borrelia lonestari. Some cases of STARI have been reported in New Jersey and Maryland.

How Ticks Develop

Larval Ixodes ticks (deer tiks) feed in the late summer, nymphs feed during spring and early summer, and adults feed predominantly in the fall. The tiny nymphs are your chief threat because they are the most active feeders, and their small size (See Figure 11.1, below) makes casual detection very difficult. In fact, three-quarters of the people who get the disease never spot the tiny ticks which tend to hide in the hair, groin, and armpits and at the back of the knees. Not all ticks, however, are infected with the Lyme spirochete. In some areas, only 1% of ticks carry the spirochete; in other areas the percentage can be much higher.

Ticks primarily inhabit grassy or wooded areas. They are not found on sand dunes, where there is no grass. Ticks don't fly, jump up from the ground, or drop from trees. Instead, they climb to the tips of vegetation and wait for you to brush by. Because the ticks are so small, and their bite is painless, you will probably be unaware when a tick attaches itself to your clothing or skin.

People Most at Risk People most at risk are those engaged in outdoor activities—campers, hikers, hunters, farmers, gardeners, telephone line workers, foresters, and military personnel on training maneuvers.

Symptoms

Because you may not have noticed the tick bite and because the symptoms of Lyme disease are sometimes passed off as “the flu,” illness can be overlooked or misdiagnosed. Ten to 20% of infected people may not even develop early symptoms. Up to 40% of victims may not develop or recall having the typical rash.

Stage 1 (early localized infection) A spreading, circular, pink or red rash (erythema migrans) is the hallmark of early Lyme disease. This rash, which originates at the site of the tick bite, is caused by the Borrelia burgdorferi spirochetes migrating in an expanding fashion from the central point of inoculation. The rash can become quite large—5 to 10 inches, or more, in diameter. The appearance of the rash is somewhat varied. In some cases it is halo shaped with an almost clear central area surrounded by a pink or red outer ring (bull's-eye rash). Other rashes have a deep red center with secondary rings and a red outer border. The red areas may be slightly raised and warm to the touch. You may also notice localized lymph node swelling and fatigue. There's a 15% to 40% chance you won't have the characteristic rash. Absence of the typical rash makes early diagnosis more difficult.

Stage 2 (early disseminated infection) After stage 1, the spirochetes spread throughout the body, causing flulike symptoms: fever, headache, muscle and joint aches, swollen glands, increased fatigue, nausea, and loss of appetite. Other symptoms include multiple skin rashes; pains in the muscles, joints, and tendons (fibromyalgia); stiff neck (meningitis); encephalitis; and facial nerve paralysis (Bell's palsy). Cardiac problems include conduction abnormalities with varying degrees of heart block, myopericarditis, and cardiomyopathy. Stage 2 symptoms can occur while the primary erythema migrans rash is still visible or can be delayed by weeks or months.

Stage 3 (late infection) If untreated, you can develop prolonged arthritis attacks in one or multiple joints (often the knees), chronic fatigue, and disorders of the nervous system (polyneuritis, paralysis, encephalopathy). Neuritis symptoms include backache with shooting pains and lack of feeling in the hands and feet.

Symptoms of encephalopathy include mental changes such as forgetting names, misplacing objects, or missing appointments. There may be problems speaking and trouble finding words. A variety of rashes with inflammation and thinning of the skin may also occur.

Prevention

The primary defense against Lyme disease and other tick-borne diseases remains avoidance of tick-infested habitats, use of personal protection measures, and checking for and removing ticks.

Tick Bite Prevention The best way to prevent tick bites is to combine protective clothing with “chemical warfare.” Cover as much exposed skin areas as weather conditions allow. Tucking long pants into socks is highly effective. Treat outer clothing with the insecticide permethrin (Chapter 8). Apply a DEET-containing insect repellent to exposed skin. Inspect your body daily for attached ticks.

Prophylactic Antibiotics Finding a tick attached to you doesn't automatically mean you will get Lyme disease because (1) the tick may not be infective, or (2) the tick may not have been attached long enough to transmit spirochetes. (Transmission of spirochetes takes 24 to 36 hours.) Nevertheless, a tick bite signifies potential risk if the tick has fed (it will be engorged with blood). A single 200-mg dose of doxycycline is effective for prevention if taken within 72 hours of the bite (reference here). Don't let a doctor prescribe 2 to 3 weeks of antibiotics just for a bite. That much antibiotic is used for treatment.

Vaccination The Lyme vaccine (Lymerix—GSK) was taken off the market in 2002 and is no longer available. Lack of a vaccine makes tick-bite prevention measures more important.

Diagnosis

The diagnosis of early Lyme disease should be based primarily on a history of possible exposure in an endemic area and on the presence of typical symptoms. To make a diagnosis of Lyme disease, you need to have either (1) the typical rash, or (2) symptoms consistent with Lyme disease, in combination with a positive blood (serologic) test.

The serological laboratory tests most widely available and employed are the Western blot and ELISA (Enzyme Linked Immunosorbent Assay). In the two-tiered protocol recommended by the CDC according to their case definition, the ELISA is performed first, and if it is positive or equivocal, a Western blot is then performed to support the diagnosis. The reliability of testing in diagnosis remains controversial. However studies show the Western blot IgM has a specificity of 94-96% for patients with symptoms suggestive of Lyme disease with infection by Borrelia burgoferi.

False-negative test results have been widely reported in both early and late disease. False negatives can take place for a broad spectrum of reasons, including cross reaction of other infections such as cytomegalovirus. and herpes simplex type virus 2.

Polymerase chain reaction (PCR) tests for Lyme disease may also be available to the patient. A PCR test attempts to detect the genetic material (DNA) of the Lyme disease spirochete, whereas the Western blot and ELISA tests look for antibodies to the organism. PCR tests are rarely susceptible to false-positive results but can often show false-negative results. The low number of spirochetes in tissue samples and body fluids is one of the reasons why it is sometimes difficult to demonstrate active Borrelia burgdorferi infection by PCR, especially in the late stage of the disease.

With the exception of PCR testing, currently there is no practical means for detection of the presence of the organism, as serologic studies only test for antibodies of borrelia. High titers of either immunoglobulin G (IgG) or immunoglobulin M (IgM) antibodies to Borrelia antigens indicate disease, but lower titers can be misleading. The IgM antibodies may remain after the initial infection, and IgG antibodies may remain for years.

Western blot, ELISA and PCR can be performed by either blood test or analysis of cerebral spinal fluid (CSF) via lumbar puncture (spinal tap). Though lumbar puncture is more definitive of diagnosis, antigen capture in the CSF is much more elusive, reportedly CSF yields positive results in only 10-30% of patients cultured. The diagnosis of neurologic infection by Borrelia should not be excluded solely on the basis of normal routine CSF or negative CSF antibody analyses. A negative result obtained by these methods can never exclude Lyme disease. However, a positive result can confirm the diagnosis or treatment failure independently of results of antibody tests.

Treatment

If the diagnosis seems clear cut on the basis of your exposure and symptoms (especially the rash), you should receive immediate antibiotic treatment. The treatment of choice for early Lyme disease is doxycycline. Don't let your doctor withhold treatment just to see if your blood test will turn positive.

Treatment recommendations are based on limited data. The duration of treatment is not well established for any stage of the disease and relapses are possible despite a full course of a recommended antibiotic. A second course of antibiotic treatment may, therefore, be required. Table 11.1 summarizes current treatment recommendations.

Treatment of Children and Pregnant Women Amoxicillin is the drug of choice for pregnant women and children younger than 8 years of age. Women who are allergic to penicillin should receive erythromycin base, 250 mg to 500 mg, four times daily for 4 weeks.

Note: The Food and Drug Administration (FDA) warns consumers and health care providers to avoid bismacine, an injectable compound prescribed by some alternative medicine practitioners to treat Lyme disease. Bismacine, also known as chromacine, contains high levels of the metal bismuth. Although bismuth is safely used in some oral medications for stomach ulcers, it's not approved for use in injectable form or as a treatment for Lyme disease. Bismacine can cause bismuth poisoning, which may lead to heart and kidney failure.

Tick Removal

  • Grasp the head of the tick with tweezers as near to the skin as possible and gently pull upward and backward until the head of the tick is completely removed. Try not to crush or puncture the tick. Don't try to twist or jerk it out. If the body of the tick tears off and the mouth parts remain embedded in the skin, see your doctor, or go to an emergency department or ambulatory care center to have the mouth parts removed. (They may need to be scraped out under local anesthesia.)

  • If the tick won't release with the above technique, apply a small amount of permethrin spray to the tick. Wait 10 minutes and try the removal technique again.

  • Don't use petroleum jelly or a hot object to remove the tick.

  • Never use bare fingers to remove a tick. The infection could be passed to you.

  • After removing the tick with tweezers, wipe off the attachment site with alcohol or Betadine.

  • Dispose of the tick in a safe manner, or cremate it with a match. However, if you want the tick examined or tested, put it in a capped container for later examination (see later).

  • When finished, wash your hands thoroughly with soap and water—or use a hand sanitizer gel, such as Purell.

Recommendations are based on limited data and should be considered tentative. The duration of treatment is not well established for any indication. Relapse has occurred with all of these regimens; patients who relapse may need a second course of treatment. There is no evidence, however, that either repeated or prolonged treatment benefits subjective symptoms attributed to Lyme disease.
2Should not exceed adult dosage.
3Neither doxycycline nor any other tetracycline should be used for children under the age of 8 or for pregnant or lactating women.
4A temporary pacemaker may be necessary.
5In late disease, the response to treatment may be delayed for several weeks or months.
Abbreviations: bid, twice daily; IV, intravenously; PO, by mouth; qid, four times daily; tid, three times daily. From The Medical Letter, Vol. 39, 1997. Reprinted with permission.

After removing the tick, observe the bite area for any sign of a rash. The typical Lyme disease rash, if it's going to occur, appears from 3 to 30 days after the bite. If you get a rash immediately, or within 24 hours after being bitten, it is not a Lyme disease rash—it is an allergic (hypersensitivity) reaction to the bite. (These allergic rashes are usually itchy.)

Lyme Disease Fact

Tests for Lyme disease may not be diagnostic during stage 1. Therefore, prompt, aggressive antibiotic treatment of early Lyme disease can be started solely on the basis of symptoms, especially a typical “bull's-eye” rash. The absence of the rash, however, should not eliminate Lyme disease from consideration if the symptoms also suggest other features of the infection.

IS THE TICK INFECTED?

Once you have removed a tick, you can have it tested for Lyme disease by polymerase chain reaction (PCR), a technique that detects the DNA of the Lyme disease spirochetes in the tick. Without knowing if the tick is infected, the medical profession is divided on whether to treat on the basis of a tick bite alone. A positive PCR test is a strong indication that you should take antibiotics after a tick bite. The PCR test can be done on live or dead ticks sent through the mail. A doctor's order is not necessary to have testing done.

Procedure: Place the tick (dead or alive) in a clean, covered prescription vial that has been thoroughly washed and rinsed with tap water. Refrigerate the vial until it can be sent. Mail the vial with a check or money order for $35 to Imugen, Inc., 220 Norwood Park South, Norwood, MA 02062. Tel: 781-255-0770. Specify that you want Lyme disease testing done because other PCR tests are also performed at this laboratory.