Monday, June 22, 2009

Lyme Tick

This 60 yo man came in for a skin cancer check. He had a basal cell removed from his forehead two years ago. The exam was negative until I checked his leg and noted a funny looking lesion. On closer examination, I realized it was a tick. It's head was embedded in the patient's leg. I removed the tick and gave the patient 200 mg. of doxycycline. This latter might be unnecessary, but a study published in the NEJM gives support to this fairly benign prophylaxis.

Reference:
Prophylaxis with single-dose doxycycline for the prevention of Lyme disease after
an Ixodes scapularis tick bite.

Nadelman RB, wt. al. Tick Bite Study Group.

Department of Medicine, New York Medical College, Valhalla 10595, USA.

BACKGROUND: It is unclear whether antimicrobial treatment after an Ixodes scapularis tick bite will prevent Lyme disease. METHODS: In an area of New York where Lyme disease is hyperendemic we conducted a randomized, double-blind, placebo-controlled trial of treatment with a single 200-mg dose of doxycycline in 482 subjects who had removed attached I. scapularis ticks from their bodies within the previous 72 hours. At base line, three weeks, and six weeks, subjects were interviewed and examined, and serum antibody tests were performed, along with blood cultures for Borrelia burgdorferi. Entomologists confirmed the species of the ticks and classified them according to sex, stage, and degree of engorgement. RESULTS: Erythema migrans developed at the site of the tick bite in a significantly smaller proportion of the subjects in the doxycycline group than of those in the placebo group (1 of 235 subjects [0.4 percent] vs. 8 of 247 subjects [3.2 percent], P<0.04). p="0.02)" p="0.02)." style="font-weight: bold;">CONCLUSIONS: A single 200-mg dose of doxycycline given within 72 hours after an I. scapularis tick bite can prevent the development of Lyme disease.



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