Lyme Disease

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 (Figure 11.1) 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.

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.

Figure 11.1 Text Actual Size of Deer Ticks in Five Stages. From left to right: larva, nymph, adult male, adult female, and engorged (fed) female tick

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.

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.

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.

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.

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.

• 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.

Table 11.1 Treatment of Lyme Disease

¹Recommendations 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.)

IS THE TICK INFECTED?