Lyme Disease

Posted by • May 2nd, 2014

The latest Clinical Practice article, Lyme Disease, comes from Dr. Eugene D. Shapiro of Yale University. Erythema migrans at the site of a tick bite is the most common sign of Lyme disease. Antibody testing is generally not helpful in patients with this condition. Treatment with doxycycline, amoxicillin, or cefuroxime is effective for early Lyme disease.

Lyme disease, a zoonosis, is transmitted by certain ixodid ticks and is the most common reportable vectorborne disease in the United States, where it is caused only by the spirochete Borrelia burgdorferi sensu stricto (hereafter termed B. burgdorferi). In Europe and in Asia, B. afzelii, B. garinii, and other related species, in addition to B. burgdorferi, cause Lyme disease.

Clinical Pearls

What are the typical characteristics of erythema migrans?

The most common sign of Lyme disease is erythema migrans. Erythema migrans usually begins as a small erythematous papule or macule that appears at the site of the tick bite 1 to 2 weeks later (range, 3 to 32 days) and subsequently enlarges. The lesion may have centrally located vesicles or necrotic areas. Erythema migrans may be asymptomatic, mildly pruritic, or, in rare cases, painful; if untreated, lesions may become as large as 61 cm (2 ft) in diameter and may last for 3 to 4 weeks before resolving. Erythema migrans lesions may occur anywhere on the body surface, although common sites are the groin, axilla, waist, back, lower extremities, and, in children, the head and neck. Although reputed to have a bull’s-eye appearance, approximately two thirds of single erythema migrans lesions either are uniformly erythematous or have enhanced central erythema without clearing around it.

What are extracutaneous signs of disseminated Lyme disease?

Extracutaneous signs of disseminated Lyme disease that may occur, with or without erythema migrans, include neurologic conditions, such as cranial-nerve (particularly facial-nerve) palsy and meningitis that mimics aseptic meningitis, as well as carditis, which is most commonly manifested as heart block. Arthritis (most often affecting the knee) is a late sign of disseminated Lyme disease, occurring weeks to months after initial infection; it is seen in less than 10% of all cases, because most patients are treated and cured at an earlier stage of the illness.

Morning Report Questions

Q: How useful are serologic tests in the diagnosis of Lyme disease?

A: Serologic tests for the diagnosis of B. burgdorferi infection are generally of little use in patients with erythema migrans. Two-tier serologic testing for antibodies to B. burgdorferi is recommended (a quantitative test, usually an enzyme-linked immunosorbent assay [ELISA] of the concentration of antibodies to B. burgdorferi and, if results are positive or equivocal, a Western immunoblot); however, it has poor sensitivity in patients with erythema migrans during the acute phase (positive results in only 25 to 40% of patients without evidence of dissemination). Even in the convalescent phase after antimicrobial treatment, a substantial proportion of patients with erythema migrans (half of those without dissemination and a quarter of those with dissemination) do not have a positive test result. The sensitivity of two-tier testing is much better in patients either with early disseminated neurologic or cardiac Lyme disease (80 to 100%) or with late manifestations of Lyme disease such as arthritis (nearly 100%).

Q: What are the most appropriate antimicrobial agents for the treatment of early Lyme disease?

A: Randomized trials have assessed several different antimicrobial agents for the treatment of erythema migrans. In these trials, rates of cure (defined as complete resolution of signs and symptoms shortly after the completion of treatment) have been about 90% with doxycycline, amoxicillin, or cefuroxime axetil. With rare exceptions, patients who were not cured continued to have only nonspecific symptoms, such as fatigue or arthralgia. If a patient has a contraindication to all those drugs, macrolide antibiotics (e.g., azithromycin, clarithromycin, or erythromycin) are an option, but they are somewhat less effective, with cure rates of about 80%. First-generation cephalosporins, such as cephalexin, are not effective in treating Lyme disease.

Table 3. Treatment of Lyme Disease.

5 Responses to “Lyme Disease”

  1. osama elbahr says:

    Thanks for this good article
    But, what is differential diagnosis of erythema migrans

  2. Dr Indran Muthiah says:

    Tick borne disease has, as far as I know, no known epidemiological profile in the 21st Century.With globalization and extensive Air Travel, Lyme Disease may appear anywhere.

  3. Julia says:

    I think the author of this article should check the new updated studies as many of the statements here are incorrect. If you are quoting data obtained from the CDC, i would suggest you recheck with a more reliable source. After all, the CDC recently revealed that they had miscalculated the number of new cases of Lyme Disease in the United States, changing the original number of 33,000 new cases to 330,000. A slight oversight.

    The Erythema Migrans EM is present in no more than 50% of Lyme patients. At least 50% have no memory of a bite at all or any type of a rash. Some studies show the actual incidence of the EM bullseye to be closer to 20-30%. It is important that your readers understand that they very well could have Lyme Disease even when a bullseye is absent. Too many people have spent years unnecessarily suffering because their Doctors dismissed Lyme Disease due to the lack of an EM. We have clearly seen how the CDC and their cronies can not be counted as responsible and reliable sources of information when it comes to Lyme Disease. They have a long history of being inaccurate with the information they give to the public . I urge anyone who has unexplained symptoms to insist on being tested at a reputable lab like e Igenex in California.

  4. Marton Szell says:

    Why do you recommend to give doxycyclin in two doses? Considering the long half life of this antibiotic an OD regimen is sufficient and increases our patients compliance.

  5. Tomasz Bochenek says:

    In my opinion early administration of any drug should be adjusted to patient body weight . It lacks – it is a big problem