Antibiotics Recommended to Prevent Lyme Disease After Deer Tick Bite
In the April 2011 issue of the Wisconsin Medical Journal, Elizabeth L. Maloney, M.D., discusses the shortcomings of the prevailing antibiotic protocol for Lyme disease prevention and recommends getting a course of antibiotics if bitten by a deer tick.
In “The Management of Ixodes scapularis Bites in the Upper Midwest,” Dr. Maloney writes: “Given that the rate of B burgorferi–infected ticks in the upper Midwest is high, that physicians may be unable to determine attachment times based on tick engorgement, and that the optimum regimens for the prophylaxis of Lyme disease and anaplasmosis are unknown, physicians may offer doxycycline 100-mg twice daily for 10 to 20 days to patients with I scapularis bites.” I scapularis is the black-legged, or deer, tick common to the Midwest; B burgorferi is the bacterium that causes Lyme disease. Deer tick bites may also transmit human granulocytic anaplasmosis (HGA), another bacterial infection that can complicate the clinical picture.
“The Infectious Disease Society of America guidelines for preventing Lyme disease were based on scant and faulty research results,” finds Dr. Maloney. “For example, one study relied on the presence of a rash to indicate infection, ignoring subjects who had other evidence of early Lyme but lacked the rash. This oversight has real-world implications because 30% of patients with Lyme disease never develop a rash.”
The IDSA recommends a single 200-mg dose of oral doxycyline to prevent Lyme disease, as long the tick bite is 1) known to be an adult or nymphal deer tick, 2) known to be attached for at least 36 hours, and 3) known to have been in a location where at least 20% of the ticks in the area are known to be infected with B burgorferi.
In most regions of Minnesota, roughly 33% of the deer ticks are infected with B burgorferi, and in the north central, east central and southeast parts of the state the rate climbs to 66%, according to studies by the Minnesota Department of Health, the Metropolitan Mosquito Control District and others.
“The application of the required criteria to primary care practices in Wisconsin and Minnesota may be problematic... The assessment criteria [of the IDSA guidelines] are based on a study that employed a medical entomologist; community physicians are not likely to have, or develop, this level of expertise. External validity is the ability of the cause-and-effects relationships in an experimental study to be generalized to a clinic setting. External validity is “poor” if the study situation differs from the typical clinical situation in ways likely to affect outcomes, as is the case here.” “Furthermore,” writes Dr. Maloney, “bites from ticks damaged or discarded following identification by non-medical personnel would not receive prophylaxis, yet withholding treatment solely on those grounds exposes patients to the risk of infections.”
Avoiding bites from deer ticks remains the best way to prevent Lyme disease and/or HGA.
Elizabeth L. Maloney, M.D. is a family physician from Wyoming, MN. She develops medical education courses on Lyme disease for physicians, nurses and chiropractors and has been published in other medical journals. Dr. Maloney also provides education on Lyme disease to private organizations and government agencies.
She is a member of the American Academy of Family Practice, the Minnesota Academy of Family Practice and the International Lyme and Associated Diseases Society (ILADS), and serves as the medical advisor for the Minnesota Lyme Association (www.mnlyme.com).
For more information on Lyme disease prevention, come out to the 5th annual MLA fundraiser, The Lyme Challenge, at Lions Park in Hugo on May 21 at 9:30am. This family-oriented event will feature a 5K/10K walk-run, a DJ spinning tunes, kid’s games, and information on Lyme disease prevention. The Hugo Lions Club will operate the food concessions, and HealthEast will offer free health assessments, including blood glucose and blood pressure checks. Info at www.mnlyme.com
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