What To Do If You Think You've Been Exposed To Lyme Disease

If you find a tick attached to your skin and you suspect it's been there for a while, what do you do?

With all the headlines about Lyme disease, it's natural to immediately wonder if you've been exposed to the Lyme bacteria. But even if you have, doctors say you can probably fend off the illness if you act quickly.

As part of WBUR's week-long series, All Things Considered host Sacha Pfeiffer spoke with Dr. Jonathan Edlow, an emergency physician at Beth Israel Deaconess Medical Center, about treatment for possible exposure to Lyme.

Sacha Pfeiffer: We know from having chatted with you to prepare for this interview that you say that some people tend to, in your words, "freak out" when they have a tick on their skin, and you say that you actually see a lot of those people in the emergency room for this. How alarmed should people be or not be when they spot a tick on their skin?

Dr. Jonathan Edlow: Well, it's certainly something that one needs to take some action, the first action being to remove the tick. This is sort of a perfect time to prevent a disease when you catch it at the stage of a tick bite because the disease hasn't really established itself yet. Certainly if the tick is still crawling around on your skin it's definitely zero risk to you. If the tick has bitten you, it's doing that to get a blood meal so it can go to the next stage of its existence. And essentially a tick goes from flat like a sesame seed to something spherical like a raisin. As it engorges with blood, it literally changes its shape.

And is there some midpoint where a tick might not be totally engorged but may still have transmitted enough bacteria to infect you?

There is, and you can look up pictures. One web site is emedicine.com, which has some good close-up photographs of partially engorged ticks. But the bottom line is that if you're not sure, it's worth speaking to your doctor.

So if there's a concern that a patient may have been exposed to Lyme disease, but it's too early for that patient to have symptoms, what is the treatment?

The treatment for a tick bite — assuming that the tick has been on you for at least 24 hours [but] it hasn't been on you for more than 72 hours, and it's a deer tick — would be 200 milligrams of Doxycycline for an older child or an adult. Treatment at that stage is really to prevent Lyme disease.

But if a person is showing Lyme symptoms, such as a rash or a fever and muscle aches, is that patient beyond the window of time in which a small dose of antibiotics can possibly help?

That's correct. The 200-milligram dose of Doxycycline is to prevent Lyme disease. What you're describing — having symptoms of a rash or a fever — that's established Lyme disease and requires a longer course of antibiotics.

What about the message that the medical community has been sending for years — that overuse of antibiotics can contribute to the problem of antibiotic-resistant bacteria? Could we be contributing to that problem by having people take small doses of antibiotics as soon as they think they've been bitten?

I think taking a 200-milligram dose of Doxycycline one time is very unlikely to contribute to all of the badness that we are creating on our planet based on resistance patterns of antibiotics. To the extent that we're preventing a disease that we would then be treating for 10 days or two weeks or three weeks of antibiotics, we're eliminating the need for a longer course of antibiotics.

Another thing to consider in all this is that Lyme disease tests can't provide a positive or negative result right away, and they're also not considered highly reliable. Would you tell us about some of those testing limitations?

Blood testing for Lyme disease is a lousy test early on. What people need to realize is that Lyme disease testing is not a test to see if the Lyme disease bacteria is present or absent. Lyme disease testing is testing for antibodies, and it takes time for those antibodies to develop. Even at the stage of early Lyme disease — when, let's say you have the bull's-eye rash, which is not always a bull's-eye, I should point out, but let's say you have a fever and chills, or you have a rash or headache — even at that stage, if you were bitten three weeks ago, your blood test may be negative. And, in fact, 50 percent of patients with early Lyme disease will be negative by their blood test. In fact, when you have the rash it's like a diagnostic gift. If you've got the rash and you can see the rash, I jump for joy because I can make a specific diagnosis with confidence and I don't need blood tests or X-rays or consultants or scans or anything.

Once you have been positively diagnosed with Lyme disease, you still take antibiotics as a treatment, but sometimes I hear people taking it for 10 days, sometimes three weeks. How are doctors deciding how long to leave that person on antibiotics?

The guidelines, first of all, go anywhere from 10 days to 21 days. I think that part of it is how the doctors read the literature and how anxious a patient is. My bias is to treat for three weeks. There have been studies in the last six, seven, eight years that suggest that a shorter course — i.e. 10 days — is adequate.