The little burrowing bacteria that bores into your pores to cause Lyme disease, EEEEEWWW!!! Darkfield 400x microscopy image of the 10-25µm long Borrelia burgdorferi spirochaete which causes Lyme disease (1993). Provided by the CDC’s Public Health Image Library (PHIL #6631) via the Wikimedia Commons
I hate those oh hell moments. I was up way too late last night, but who can pass up the opportunity to see Patti Smith playing Horses (and more) for the 40th anniversary of the album. Only 44? Behind the Eagles? No way. I would nudge it up a few more spaces. Hard to believe I was 18 when that album came out. Horses is one of the few albums that made the transition from vinyl to CD. It was a tremendous show, and at 69 Patt performs with the energy and passion of a 29 year old. And she sure can spit. I had the evening off, so food and drinks at Swine until well past midnight. First time my wife and I closed a bar. I am too old for this.
But as I was blearily drinking my a.m. coffee on a dreary PDX morning, I opened the browser to SBM and there was a post by Jann. Oh hell. That means I have a post due tomorrow and I had lost track of the time over the holidays. I thought my next post was next Friday. Oh. Hell. So unlike most posts which I write over a week, this one was done in about 4 hours. And I am sure it will show.
How do you diagnose an infection?
Not always so simple. You always start with a history and, for infectious diseases, an exposure history is paramount. People get what they are exposed to, so you want to know travel, animals, diet, water, sex etc. If you have ridden a horse to have sex in an Indian lake while drinking raw milk (not really an unusual history in my practice; people do the darndest things) you have exposure risks for a variety of infections. If you have not left the Willamette Valley it is unlikely that the cause of the illness is malaria, although you always have to consider that the infection came to the patient rather than the other way around. (more…)
It’s that time of year when every day I can expect to see at least one patient with a concern about Lyme disease. In Lyme-endemic regions such as Western Massachusetts, where I practice pediatrics, summer brings a steady stream of children to my office with either the classic Lyme rash (erythema chronicum migrans, or ECM), an embedded tick, a history of a tick bite, or non-specific signs or symptoms that may or may not be due to Lyme disease. Sometimes the diagnosis is relatively straightforward. A child is brought in after a parent has pulled off an engorged deer tick, and there is a classic, enlarging ECM rash at the site of the bite. More often the presentation is less clear, requiring detective work and science-based reasoning to make an informed decision and a diagnostic and therapeutic plan based on the best available evidence. Depending on the story, the plan may include immediate treatment without any testing (as in the straightforward case described above), immediate testing without treatment pending test results, or waiting as we watch and see how a rash progresses before doing anything. An example of this latter course of action would be when a patient comes in with a pink swelling at the site of a new tick bite. In this case, it may not be clear if the swelling is a Lyme rash or simply a local reaction to the bite, a much more common occurrence. The classic ECM rash (an enlarging, red, circular, bull’s-eye rash at or near a tick bite) typically develops 1-2 weeks after a tick bite, but can occur anywhere from 3-30 days later. It then expands and darkens over another 1-3 weeks before fading. This classic rash is not the most common rash of Lyme disease, however, as it occurs in only about 30% of cases. Instead, the rash may be uniformly pink or red (or even darker in the center) without the target-like appearance, or may be a linear rash, expanding outward from the tick bite site. In the case of a patient who comes in with a vague, pink swelling within a day few days of a tick bite, we will typically wait and see what happens to the rash. If it is a local reaction, it will likely resolve within another few days. With Lyme disease, the rash will continue to enlarge and declare itself as an ECM rash. Another unclear and not uncommon situation is when a patient comes in with non-specific symptoms such as fatigue, musculoskeletal pains, and headache. If warranted by the history and the physical exam, we may in this case order Lyme testing. This may not give us an answer even if the patient has Lyme disease, because results are often negative in the first few weeks of the disease. In this case, if symptoms persist or evolve, we will repeat the testing in another few weeks at which point true Lyme disease will test positive and can then be treated. The good news is that the treatment of Lyme disease, particularly in the early, localized phase of the disease, is extremely safe and effective with a 14-day course of antibiotics. The testing is also relatively straightforward, with very good sensitivity and specificity when performed correctly. And this is where the bad news comes… (more…)