Lyme disease is the most common tick-borne disease in the United States, affecting adults and children. It is endemic in several regions of the country, particularly the Northeast, Upper Midwest and Northwest. The Infectious Diseases Society of America (IDSA) has issued evidencebased practice guidelines on the treatment of Lyme disease. The guidelines provide recommendations for the management of patients who have been diagnosed with Lyme disease or persons bitten by ticks suspected of carrying the disease.

According to the IDSA, the guidelines are the first evaluation of various Lyme disease treatments using a disciplined, systematic, rules-of-evidence approach to the medical literature and are meant to complement existing practice standards. A panel of 12 infectious disease specialists with collective expertise in clinical, medical entomologic and public health aspects of Lyme disease participated in the formation of the recommendations.

The IDSA practice guidelines provide primary management options, evidence and recommendations for the following: tick bites and prophylaxis, early Lyme disease, Lyme arthritis, late Lyme disease and chronic Lyme disease or post-Lyme disease syndrome. The guidelines appear in a supplement to the September 2000 issue of Clinical Infectious Diseases and are also available on the IDSA Web site athttp://www.idsociety.org.

Lyme Disease Prophylaxis

For persons who remove attached ticks, the panel considered the following management options: (1) treating all such persons; (2) treating only persons thought to be at high risk (e.g., those removing a nymphal or adult vector tick after 48 hours of attachment); (3) treating only persons who develop erythema migrans or other clinical signs and symptoms of tick-borne infection; and (4) treating all persons who seroconvert from negativity to positivity for serum antibodies to Borrelia burgdorferi.

The IDSA panel compared the risks and consequences of developing Lyme disease (including the risk of late complications) for persons bitten by vector ticks with the cost and adverse effects of prophylactic antimicrobials. The effect of the recent licensing of a recombinant outer-surface protein A (OspA) vaccine for the prevention of Lyme disease was also considered.

Currently, the best way to prevent infection with B. burgdorferi and other Ixodes-transmitted infections is to avoid tick-infested areas. If exposure to Ixodes scapularis or Ixodes pacificus ticks is unavoidable, the risk of infection may be reduced by using light-colored, protective clothing and tick repellants; checking the entire body for ticks daily; and promptly removing attached ticks with fine-toothed forceps before transmission of B. burgdorferi can occur.

Routine use of antimicrobial prophylaxis or serologic testing after a tick bite is not recommended. Some experts suggest antibiotic therapy for patients bitten by I. scapularis ticks that may have been attached for more than 48 hours, based on the degree of engorgement of the tick with blood, in conjunction with epidemiologic information about the prevalence of tick-transmitted infection. However, accurate determinations of species of tick and degree of engorgement are not routinely possible, and data are insufficient to demonstrate effectiveness of antimicrobial therapy in this setting.

Persons who remove attached ticks should be monitored closely for signs and symptoms of tick-borne diseases for up to 30 days. Physicians should watch for the occurrence of a skin lesion at the site of the tick bite, which may suggest Lyme disease, or for a temperature of more than 38°C (100.4°F), which may suggest human granulocytic ehrlichiosis or babesiosis. Persons who develop a skin lesion or other illness within one month after removing an attached tick should promptly seek medical attention because they may have acquired a tick-borne disease.

Health care professionals, especially those in regions where Lyme disease is endemic, should become familiar with its clinical manifestations, recommended practices for testing and therapy, as well as for human granulocytic ehrlichiosis and babesiosis. Testing ticks for infectious organisms is not recommended, except in research studies. Previous vaccination with the recently licensed recombinant OspA vaccine preparation reduces the risk of developing Lyme disease associated with tick bites but should not alter the above recommendations.

Early Lyme Disease

For persons with early Lyme disease, the panel considered the following management options: oral antimicrobial therapy for early localized infection (i.e., solitary erythema migrans) and oral versus intravenous (IV) therapy for cases of early disseminated infection (i.e., patients presenting with multiple erythema migrans lesions, carditis, cranial-nerve palsy, meningitis or acute radiculopathy).

The IDSA panel compared the risks and consequences of developing late complications of Lyme disease with the possible adverse effects of antimicrobial therapy. The desired outcome is to resolve the signs and symptoms of early Lyme disease and to prevent late complications.

Administration of doxycycline in a dosage of 100 mg twice daily or amoxicillin in a dosage of 500 mg three times daily for 14 to 21 days is recommended for the treatment of early localized or early disseminated Lyme disease associated with erythema migrans, in the absence of neurologic involvement or third-degree atrioventricular heart block. Doxycycline is relatively contraindicated during pregnancy or lactation and for children younger than eight years.

Administration of macrolide antibiotics is not recommended as first-line therapy for early Lyme disease and should be reserved for patients who cannot tolerate amoxicillin, doxycycline and cefuroxime axetil. For children, IV ceftriaxone or cefotaxime is recommended; IV penicillin G may be used as an alternative. Treatment of pregnant patients can be identical to that for nonpregnant patients with the same disease manifestation, except that tetracyclines should be avoided.

Late Lyme Disease

The IDSA panel considered various oral and parenteral antimicrobial regimens for the treatment of the late manifestations of Lyme disease. Late manifestations include arthritis (oligoarticular), encephalopathy (characterized primarily by memory deficit, irritability and somnolence) and neuropathy (manifested primarily by distal paresthesias or radicular pain).

Because of the lack of data on ophthalmologic complications, which are very rare, the IDSA panel was unable to make recommendations concerning keratitis and other possible ocular manifestations of Lyme disease. In the treatment of late manifestations, response is typically slow and improvement or resolution of symptoms may take weeks or months. However, appropriate antibiotic treatment results in eventual recovery in most patients.

The IDSA panel compared the risks and consequences of ineffective treatment of late Lyme disease with the problems resulting from adverse effects of antimicrobial therapies. The desired outcome is to effectively treat the late complications of Lyme disease while minimizing the adverse effects of antibiotic therapy.

Lyme arthritis can usually be treated successfully with oral or IV antimicrobial agents. Doxycycline or amoxicillin, given for 28 days, is recommended for patients without clinical evidence of neurologic disease. The IDSA panel recommends amoxicillin for all children and doxycycline for children eight years and older. Compared with IV antibiotics, oral therapy is easier to administer, associated with fewer serious complications and considerably less expensive. However, some patients treated with oral agents have subsequently manifested overt neuroborreliosis, which may require IV therapy. Further controlled studies are needed to compare oral treatment with IV therapy.

Neurologic evaluation, including lumbar puncture, should be done in patients for whom there is strong clinical suspicion of neurologic involvement. Patients who have persistent or recurrent joint swelling after recommended courses of antibiotic therapy should repeat treatment with another four-week course of oral antibiotics or with a two- to four-week course of IV ceftriaxone.

Patients with late neurologic disease affecting the central nervous system should be treated with IV ceftriaxone in a dosage of 2 g once daily for two to four weeks. Alternative parenteral therapy may include administration of cefotaxime or penicillin G. Treatment with ceftriaxone is recommended for children. Alternatives are IV cefotaxime or penicillin G.

Chronic Lyme Disease or Post-Lyme Disease Syndrome

Following an episode of Lyme disease that has been treated appropriately, some persons have a variety of subjective complaints such as myalgia, arthralgia or fatigue. Some of these patients have been classified as having “chronic Lyme disease” or “post-Lyme disease syndrome,” which are poorly defined entities. However, the IDSA panel reports that there is insufficient evidence to regard “chronic Lyme disease” as a separate diagnostic entity.