John Bartlett, MD


July 23, 2003

In This Article

Preventing Lyme Disease

Hayes EB, Piesman J. How can we prevent Lyme disease? N Engl J Med. 2003;348:2424-2430. Abstract The authors from the CDC review methods to prevent Lyme disease. In terms of rationale to do this, they note that 20% of cases are mild and resolve with no therapy and 90% of those who are treated for early-stage disease with amoxicillin or doxycycline have an excellent response to treatment. Nevertheless, erythema migrans may be accompanied by facial palsy, meningitis, or carditis; 10% to 20% have no recognized erythema migrans stage or do not seek medical attention and may present with late sequelae, including neurologic or joint complications. The late complications require intravenous treatment, and 30% have residual symptoms. These latter observations account for the interest in disease prevention as follows:

  • Tick checks: Removal of the Ixodes scapularis tick within 36 hours after attachment reduces the risk.[35,36,37,38] In fact, the authors consider daily tick checks to be the most acceptable and effective prevention method. The use of insect repellants and protective clothing is considered supplementary.

  • Prophylactic antibiotics: A single dose of 200 mg doxycycline within 72 hours after a recognized I scapularis bite is 87% effective in preventing erythema migrans.[39] The gastrointestinal intolerance to the 200-mg dose may be reduced by administration with food. Treatment should be considered if the tick was attached for 36-72 hours. It helps to know the principal tick species, and the tick should be removed. Patients who have been bitten by a tick should be told to seek medical attention for this intervention.

  • Tick control: The most effective method is a single application of an acaricide such as cardaryl, cyfluthrin, or deltamethrin in early May, which reduces the population of I scapularis nymphs by 68% to 100%[40]). Deer control is less practical because all or nearly all deer must be removed to substantially decrease the number of ticks.

Comment: The authors provide practical information for preventing Lyme disease. The vaccine has been withdrawn due to poor sales attributed to high price, short-term benefit, and unsubstantiated concerns for autoimmune side effects. On a practical note, the Medical Letter recently reviewed insect repellants.[41] The conclusion is that DEET-containing insect repellants, especially the long-acting EDTIAR formulation (available in the United States as Ultrathon from 3M), effectively prevents mosquito and tick bites for 6-12 hours and is generally safe. Less well known is that Permethrin (Nix) is more effective against ticks than DEET, is marketed as a solution or spray (Repel Permanone etc.) and can be applied to clothing, tents, sleeping bags etc. Permethrin is nonstaining, nearly odorless, resists immersion in water, and can persist through 20 or more washings. Thus, their recommendation is to wear protective clothing treated with permethrin and use DEET on exposed skin as the optimal method to prevent mosquito and tick bites.


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