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Tick-Borne Diseases, Lyme: Treatment & Medication

Author: Jonathan A Edlow, MD, Associate Professor of Medicine, Department of Emergency Medicine, Harvard Medical School; Vice Chairman, Department of Emergency Medicine, Beth Israel Deaconess Medical Center
Contributor Information and Disclosures

Updated: Aug 26, 2009

Treatment

Emergency Department Care

Clinical guidelines are available from the American Academy of Neurology, Infectious Diseases Society of America, and International Lyme and Associated Diseases Society.^16,17,18

Treatments for tick bites, EM, early disseminated disease, and arthritis are as follows:

• Tick bite without other symptoms or signs: Several factors influence the decision to treat tick bites with therapy to prevent Lyme disease.
  • 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.¹⁹ It also corroborated the finding that duration of attachment is an important marker for transmission.
  • However, findings of other studies of culture-proven EM in the United States and Europe suggest that a nontrivial minority of patients had tick attachments of less than 24 hours, some less than 6 hours. Therefore, one cannot be dogmatic with the criterion of duration of tick attachment. Poor technique in tick removal also may facilitate infection. For further information, see Tick-borne Diseases, Introduction.
  • Although most patients do not require treatment, consider tick bite prophylaxis on a case-by-case basis. Base the decision on the species of the tick, duration of attachment (degree of engorgement of the tick is a surrogate marker), geography (percentage of ticks infected where the bite took place), method of tick removal, anxiety level of patient, and pregnancy (lower threshold to treat pregnant women).
  • After performing this exercise in clinical decision-making, one may decide to treat a given patient with prophylactic antibiotics. In the studies mentioned previously, no patient in the treatment group (which received 10 d of antibiotic treatment) had the disease. Using these older data, if one were to choose to treat, 10 days of oral amoxicillin, doxycycline, or cefuroxime axetil would seem prudent, depending on patient factors such as age, allergy, and pregnancy.
  • In one of the most recent studies (2001), a single 200-mg dose of doxycycline was used for prophylaxis with excellent results.¹⁹ Therefore, in adults, a single dose for prophylaxis makes sense. Because the above study did not include them, the correct dose for children is not known. The earlier studies all used 10 days of treatment but, given the data from adults, it is very likely that a much shorter course would be effective in children as well.
  • Serologic testing plays no role in the care of patients with tick bites.
• Solitary EM: Oral antibiotics (eg, amoxicillin, doxycycline, cefuroxime axetil, erythromycin, azithromycin, amoxicillin-clavulanate) should be administered for 10-30 days. The author recommends therapy of 3 weeks duration. Given recent findings that early disseminated Lyme disease responds very well with 21 days of oral therapy,²⁰ not exceeding that duration for localized disease seems logical. That said, one recent study suggests that 10 days of antibiotic treatment is just as effective as 20 days.²¹
• Early disseminated disease findings such as isolated facial palsy or secondary skin lesions (not meningitis) or disease with first-degree heart block (not a high-degree heart block) may be treated with oral antibiotics for 21-30 days. Recent data show that 21 days of oral doxycycline is as effective as 14 days of intravenous ceftriaxone for disease in this stage. A more recent European study treated 152 patients with early disseminated Lyme (neuroborreliosis, arthritis, and other musculoskeletal manifestations) with 3 weeks of ceftriaxone (2 g daily) and then randomized them to placebo versus amoxicillin for 100 days. The outcomes were the same.²²
• Early disseminated disease with meningitis or a high-degree heart block may be treated with intravenous ceftriaxone for 2-4 weeks. In the case of heart block, a permanent pacemaker rarely is necessary, but close monitoring in a telemetry unit is warranted. Once patients are no longer dependent on the pacemaker, their intravenous antibiotics may be switched to oral antibiotics. Occasionally, prednisone may hasten resolution of the conduction defect. Note that, in the case of meningitis, European data suggest that 2 weeks of oral doxycycline is equivalent to intravenous ceftriaxone. Because of differences in strains of Borrelia in Europe compared to North America, it is not clear if this therapeutic equivalence is true in North American patients.¹⁵  
• Arthritis may be treated with oral antibiotics for 30-60 days, and intravenous ceftriaxone may be administered for coexistent neurologic disease.

Consultations

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.

Medication

Early Lyme disease usually responds well to antibiotics. Data regarding the route and duration of therapy are evolving and are, to some extent, controversial. Nevertheless, several general principles apply.

Solitary EM can be treated for 10-30 days with oral regimens. Rashes of longer duration and more severe symptoms may require a longer duration of therapy. Because good data suggest that asymptomatic early dissemination occurs up to 44% of the time and that mild early disseminated disease is effectively treated with 3 weeks of oral antibiotics, the author prefers this longer duration. However, one study found no significant difference between 10 days of treatment and 20 days of treatment.²¹ Good data suggest that patients with multiple (secondary) EM or facial palsy without meningitis fare as well with 21 days of oral doxycycline therapy as they do with 14 day of intravenous ceftriaxone therapy. Patients with meningitis, radiculoneuritis, and a high-grade atrioventricular block should be treated with intravenous regimens. A few physicians believe that longer-term parenteral antibiotics are needed for refractory cases.

Antibiotics

Empiric antimicrobial therapy must be comprehensive and cover all likely pathogens in the context of the clinical setting. Consider coverage for co-infecting organisms, such as Ehrlichia species.

Amoxicillin (Amoxil, Biomox, Polymox)

Treats infections caused by susceptible organisms. PO DOC for pediatric patients <9 y. Duration of therapy depends on specific disease manifestations.

Doxycycline (Doryx, Bio-Tab)

PO DOC for adults. Key advantage of covering other tick-borne pathogens that may have been cotransmitted (eg, Ehrlichia species, Rickettsia species). Interferes with bacterial cell wall synthesis during active multiplication, causing cell wall death and resultant bactericidal activity against susceptible bacteria.

Cefuroxime (Ceftin, Kefurox, Zinacef)

Only FDA-approved drug for Lyme disease, but it is a second-line drug for economic reasons. Condition of patient, severity of infection, and susceptibility of microorganism determines proper dose and route of administration.

Erythromycin (Erythrocin, Ery-Tab)

Inferior to other drugs listed above. Use only if above drugs are contraindicated.

Ceftriaxone (Rocephin)

Third-generation cephalosporin that is the IV DOC. Excellent activity against B burgdorferi and has favorable pharmacokinetics. Inhibits bacterial cell wall synthesis by binding to one or more penicillin-binding proteins. Bacteria eventually lyse because of ongoing activity of cell wall autolytic enzymes, while cell wall assembly is inhibited.

Penicillin G (Pfizerpen)

Useful drug but must be administered 6 times/d. Interferes with bacterial cell wall synthesis during active multiplication, causing cell wall death and resultant bactericidal activity against susceptible bacteria.

Tetracycline (Sumycin)

Treats susceptible bacterial infections of gram-positive and gram-negative organisms, as well as infections from Rickettsia species. Also effective against ehrlichiosis. Inhibits bacterial protein synthesis by binding with 30S and possibly 50S ribosomal subunits of susceptible bacteria.

Azithromycin (Zithromax)

Mixed data exist regarding use in early Lyme disease. While one large, randomized North American study showed azithromycin to be inferior to amoxicillin, treatment duration in the 2 groups were not equal, even when the prolonged half-life of azithromycin was considered. At least 5 other smaller studies have revealed that it was as effective as other antibiotics tested. This is not a first- or second-line drug but could be useful in some situations.

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