Lyme Disease in Emergency Medicine Treatment & Management

ED care of patients with Lyme disease depends on the presenting complaint. In general, Lyme disease is not fatal, and the emergency physician may be able to consult specialists and refer the patient to a primary care physician. That said, it makes sense to start antimicrobial therapy in the ED, or with a prescription to be filled upon leaving the ED.

The following clinical guidelines are the latest recommendations from the Infectious Diseases Society of America. Clinical guidelines are available from the American Academy of Neurology, Infectious Diseases Society of America, and International Lyme and Associated Diseases Society.^{[18, 19, 20]}

See the tables below.

Table 1. Clinical presentation and therapy for the stages of Lyme Disease (Open Table in a new window)

Table 2. Adult and Pediatric treatment options, dosages, and routes of administration (Open Table in a new window)

Tick bite without other symptoms or signs

For prevention of Lyme disease after a recognized tick bite, routine use of antimicrobial prophylaxis or serologic testing is not recommended. A single dose of doxycycline may be offered to adult patients (200 mg dose) and to children older than 8 years (4 mg/kg, up to a maximum dose of 200 mg) when all of the following circumstances are present:^[19]

• The attached tick can be reliably identified as an adult or nymphal I scapularis tick that is estimated to have been attached for longer than 36 hours on the basis of the degree of engorgement of the tick with blood or of certainty about the time of exposure to the tick
• Prophylaxis can be started within 72 hours of the time that the tick was removed
• Ecologic information indicates that the local rate of infection of these ticks with B burgdorferi is more 20%
• Doxycycline treatment is not contraindicated

Animal studies have shown that transmission of infection is unlikely if the duration of tick attachment is less than 24 hours, and transmission is very likely for ticks attached for longer than 72 hours. This finding presumes that the tick is infected in the first place and the percentage of Ixodes ticks that are infected varies with geography. It also depends on the species of tick. Non-Ixodes ticks and other insects, although they can contain the organism, are highly unlikely to cause disease. The one clinically relevant exception may be bites by A americanum in the central and southern midwestern United States, but data exist on treating these tick bites prophylactically at the present time.

Several randomized placebo-controlled studies have been conducted to investigate prophylactic treatment of tick bites. All revealed that the rate of symptomatic infection and asymptomatic seroconversion is about 2% in placebo groups. This study occurred in areas in which about 15-30% of ticks were infected; this finding indicates that many bites from infected ticks do not result in transmission of the spirochete. These studies form the basis of the often-cited recommendation to withhold tick bite prophylaxis.

In 2001, a study was published showing that only female nymphal ticks transmitted Lyme disease.^[21] It also corroborated the finding that duration of attachment is an important marker for transmission.

Amoxicillin should not be substituted for doxycycline in persons for whom doxycycline prophylaxis is contraindicated because of the absence of data on an effective short-course regimen for prophylaxis, the likely need for a multiday regimen (and its associated adverse effects), the excellent efficacy of antibiotic treatment of Lyme disease if infection were to develop, and the extremely low risk that a person with a recognized bite will develop a serious complication of Lyme disease.

Solitary EM

Doxycycline, amoxicillin, or cefuroxime axetil for 14 days (range, 10–21 d for doxycycline and 14–21 d for amoxicillin or cefuroxime axetil) is recommended for the treatment of adult patients with early localized or early disseminated Lyme disease associated with erythema migrans, in the absence of specific neurologic manifestations or advanced atrioventricular heart block. Each of these antimicrobial agents has been shown to be highly effective for the treatment of erythema migrans and associated symptoms in prospective studies. Treatment duration was previously recommended to be longer, but several studies have shown similar efficacy between 10-day and longer courses (20-21 d).^{[22, 23]}

Antibiotics recommended for children include amoxicillin, cefuroxime axetil, or, if the patient is older than 8 years, doxycycline may be used.

Macrolide antibiotics are not recommended as first-line therapy for early Lyme disease, because those macrolides that have been compared with other antimicrobials in clinical trials have been found to be less effective. When used, they should be reserved for patients who are intolerant of, or should not take, amoxicillin, doxycycline, and cefuroxime axetil.

Lyme meningitis and other manifestations of early neurologic Lyme disease

The use of ceftriaxone in early Lyme disease is recommended for adult patients with acute neurologic disease manifested by meningitis or radiculopathy. Possible satisfactory alternatives include parenteral therapy with cefotaxime or penicillin G. For patients who are intolerant of β-lactam antibiotics, increasing evidence indicates that oral doxycycline (200–400 mg/d in 2 divided doses orally for 10–28 d) may be adequate.

Lyme carditis

Patients with atrioventricular heart block and/or myopericarditis associated with early Lyme disease may be treated with either oral or parenteral antibiotic therapy for 14 days (range, 14–21 days). Hospitalization and continuous monitoring are advisable for: (1) symptomatic patients, such as those with syncope, dyspnea, or chest pain; (2) patients with second-degree or third-degree atrioventricular block; (3) patients with first-degree heart block when the PR interval is prolonged to more than 30 milliseconds (because the degree of block may fluctuate and worsen very rapidly in such patients).

For patients with advanced heart block, a temporary pacemaker may be required; expert consultation with a cardiologist is recommended. Use of the pacemaker may be discontinued when the advanced heart block has resolved. An oral antibiotic treatment regimen should be used for completion of therapy and for outpatients, as is used for patients with erythema migrans without carditis.

Arthritis

Lyme arthritis can usually be treated successfully with antimicrobial agents administered orally, with an extended treatment time of 28 days. For patients who have persistent or recurrent joint swelling after a recommended course of oral antibiotic therapy, it is recommended re-treatment with another 4-week course of oral antibiotics or with a 2–4-week course of ceftriaxone IV.

Late neurologic Lyme disease

Adult patients with late neurologic disease affecting the central or peripheral nervous system should be treated with IV medication. Response to treatment is usually slow and may be incomplete. Retreatment is not recommended unless relapse is shown by reliable objective measures.

Pregnancy

Pregnant and lactating patients may be treated in a fashion identical to nonpregnant patients with the same disease manifestation, except that doxycycline should be avoided.

The need for consultation depends on the emergency physician's confidence in the clinical diagnosis.

At times, input from a dermatologist, neurologist, infectious diseases specialist, or cardiologist assists in making a firm diagnosis, particularly in the setting of chronic disease.

Always refer patients to primary care physicians to monitor for later manifestations of the disease.