Many Vermonters wonder what to do when they are bitten by a tick. Some may call their doctor and get a prescription for up to 200mg of doxycycline, the antibiotic used to treat Lyme disease. This protocol was reinforced by a recent article in the Journal of Emergency Medicine recommending it as a prophylactic for people bitten by a black-legged tick in areas where the rate of ticks infected with Lyme bacteria is greater than 20% (in some areas of Vermont it is over 59%).
Several problems that suggest this single dose of doxycycline may not be the best prophylactic for Lyme disease.
1.The recommendation is based on a questionable conclusion.
The study claimed to show the effectiveness of single dose of doxycycline to prevent Lyme disease. The study actually shows a reduction in the appearance of erythema migrans (“bulls-eye”) rashes, a possible symptom of Lyme disease – but not the disease itself. In Vermont the incidence of EM rashes in confirmed Lyme disease is decreasing. The absence of an EM rash does not indicate the absence of Lyme disease.
2.The recommendation is based on only one study.
The recommendation is based on a single study published in 2001 in the New England Journal of Medicine. The International Lyme and Associated Diseases Society’s (ILADS) guidelines note that the evidence supporting a single dose of doxycycline to prevent Lyme disease was “sparse, coming from a single study with few events, and, thus, imprecise.”
3.The study only lasted 6 weeks.
The Vermont Department of Health noted symptoms of Lyme disease can begin “weeks to months” after a tick-bite. The subjects of the study were assessed at 3 and 6 weeks with no follow up. There is no way to know if the single dose of doxycycline prevented later manifestations of Lyme disease.
5.Taking prophylactic doxycycline may result in negative blood tests for Lyme disease.
Antibiotics may affect the immune response to Lyme bacteria which could later result in a false-negative blood test for Lyme disease, potentially causing delays in diagnosis or treatment. According to the CDC, “Some people who receive antibiotics (e.g., doxycycline) early in disease (within the first few weeks after tick bite) may not develop antibodies or may only develop them at levels too low to be detected by the test.”
The IDSA guidelines recommend the single dose doxycycline as a prophylactic for Lyme disease. However, ILADS’ preferred prophylactic treatment for a person in an endemic area who discovers a feeding blacklegged (deer) tick is “100–200 mg of doxycycline, twice daily for 20 days” and they note “Other treatment options may be appropriate on an individualized basis.” (ILADS acknowledges this recommendation is based on “very low-quality evidence” and suggests that some patients may require higher doses of antibiotics, or individualized treatments.)
Vermonters who are bitten by a blacklegged tick should consider all the information available about preventing Lyme disease as well as their own personal risk factors, and discuss their options with informed health-care providers.
If an individual believes prophylactic antibiotics are not the right choice, other options are available. One is to wait and carefully watch for symptoms of tick-borne diseases to appear. (If a person does become ill, it is important to contact a health-care provider immediately as Lyme and other tick-borne diseases can be more effectively treated if diagnosed early.) Some Vermonters choose herbal, medicinal or dietary options that can help support their immune system to fight off potential tick-borne infections.
Remember, the most effective way to avoid Lyme and tick-borne diseases is to take proper prevention measures. Always do thorough tick-checks, wear insect repellent, and put clothes in the dryer on high for 10 minutes after outdoor activity in tick habitat.