The New England Journal of Medicine published an article on recommended
treatment for early stage Lyme disease just a couple weeks ago. I work at
NIH and have employee access to the NEJM article. I would be happy to email
the PDF to anyone interested (although this isn't strictly kosher by our
government rules). I want to make clear that I am NOT a physician, and my
job at NIH isn't involved with Lyme disease research. Here's the reference:
 

Wormser, GP (2006) Early stage Lyme disease. NEJM 354: 2794

In this article, one recommendation for people with a deer tick bite is:

"Doxycycline chemoprophylaxis can further reduce the chance of Lyme disease
after a bite froman I. scapularis tick. In a randomized trial, a single
200-mg dose of doxycycline administered within three days after tick removal
reduced the risk of erythema migrans at the bite site from 3.2 to 0.4
percent — that is, a risk reduction of 87 percent.(Ref.12) In regions in
which the disease is highly endemic, the use of a single dose of doxycycline
should be considered for persons who are known to have been bitten by a
nymphal or adult I. scapularis tick that was estimated to have been attached
for at least 36 hours.(Ref. 36)"

Translation into English:
In a clinical trial, people bitten by a deer tick that remained attached for
at least 36 hrs who were given a single preventative dose of 200 mg
doxycycline had an 87% lower chance of showing Lyme disease symptoms. The
study recommends this treatment for adults who live in deer tick endemic
areas - which Maryland is, according to a CDC report from 2002.
http://www.cdc.gov/ncidod/EID/vol8no4/00-0413.htm.

The Lyme disease research field is a highly contentious and polarized
medical minefield - there is a lot of animosity between some patient
advocacy groups and some researchers over whether the researchers are taking
patient concerns and symptoms seriously. If you look up Lyme disease on
Google, you will find a lot of angry folks out there, quack treatments, and
physicians and researchers that will argue over every study and treatment
recommendation.

I trust a study that has gone through the peer-review process at the New
England Journal of Medicine, and would hope that anyone's doctor would be
willing to give doxycycline based on these recommendations. In my opinion,
this is not a case of unnecessary abuse of antibiotics; in this case, the
possible consequences of untreated Lyme disease or Erlichiosis, combined
with the high probability that deer ticks in our area carry one of the
diseases, make this a no-brainer decision.

Again, I want to emphasize that this my personal opinion, and doesn't
represent an official judgement by the NIH.

Mary LaMarca
Silver Spring, MD