[at-l] Pre-Emptive 1-dose treatment for Lyme's

[janl2@xxxxxxxxxxxxxx (Jan Leitschuh)]

I had a hard time tracking this info down, so I will post it here for
the archives, should anyone ask again.

Bottom line:

"A single 200-mg dose of doxycycline given within 72 hours after an
 I. scapularis tick bite can prevent the development of Lyme disease."


N Engl J Med 2001 Jul 12;345(2):79-84
Prophylaxis with single-dose doxycycline for the prevention of Lyme
disease
after an Ixodes scapularis tick bite.

Nadelman RB, Nowakowski J, Fish D, Falco RC, Freeman K, McKenna D,
Welch P, Marcus R, Aguero-Rosenfeld ME, Dennis DT, Wormser GP; Tick
Bite
Study Group.

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

 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). The efficacy of
treatment
was 87 percent (95 percent confidence interval, 25 to 98 percent).
Objective extracutaneous signs of Lyme disease did not develop in any
subject, and there were no asymptomatic seroconversions. Treatment
with
doxycycline was associated with more frequent adverse effects (in 30.1
percent of subjects, as compared with 11.1 percent of those assigned
to placebo; P<0.001),
primarily nausea (15.4 percent vs. 2.6 percent) and vomiting (5.8
percentvs. 1.3 percent). Erythema migrans developed more frequently
after
untreated bites from nymphal ticks than after bites from adult
female ticks
(8 of 142 bites [5.6 percent] vs. 0 of 97 bites [0 percent],
P=0.02) and
particularly after bites from nymphal ticks that were at least
partially engorged with blood (8 of 81 bites [9.9 percent], as
compared with 0 of 59 bites from unfed, or flat, nymphal ticks [0
percent]; P=0.02).

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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