A tick's tale

People have always been fascinated by medical comedies, medical dramas and medical reality shows. One of the most interesting of the current crop has to be “House, M.D.”—not because it is the most believable, but because it is by far the most inaccurate. Dr. Gregory House is the very antithesis of a great physician: arrogant, belittling to patients, rude to colleagues. And if that weren't enough, his team members fare no better on the reality scale. They do all their own procedures (including brain biopsies), run their own labs and process their own slides. They even break into people's homes occasionally to search for possible exposure risk.

The patients on “House, M.D.” also present with the most bizarre diseases, and common diseases show up with the most uncommon presentations. One episode featured a woman who had an atypical presentation of Lyme disease. The confirmation of the diagnosis ultimately rested on finding the tick, but it was nowhere to be found. That is, until Dr. House did a pelvic exam and discovered the culprit. Where in the world would you ever see something that outlandish? Only on T.V., right?

Well, maybe not.

We were on our second night on call on the general medicine service when an 81-year-old woman arrived after traveling eight hours through cornfields and herds of cattle. Her doctor back home had done all he could for her problem, and this was her third hospitalization in the last month. She was looking for answers.

The woman had fever of unknown etiology, myalgias and cough—a vast differential we hoped to narrow. We started with the broad, open-ended questions and then whittled down to the details that underpinned the differential. “Have you had any blurry vision or jaw claudication?” No. “What about any recent travel?” No. “Do you spend a lot of time outside?” Yes. “Have you noticed any recent tick bites?” Yes! Now here was a differential diagnosis we could sink our teeth into.

On further questioning, it turned out the patient was an avid gardener and spent a great deal of time outside. Recently a tick had come to call, and decided to stay for dinner. When the patient finally noticed the critter, she went to her primary doctor to have it removed. For the sake of thoroughness, we nonchalantly asked where the tick was located. She started to shift uncomfortably in her bed. She blushed slightly, pointed towards her groin, and said, “Down there.” Time stopped; this was unbelievable! Things like that only happen on T.V., not to one of our patients. Her diagnosis seemed all but certain now. A few clicks on the computer, an order for a tick serology panel, and the diagnosis would be clinched. Lyme disease. No fun for her, but very curable. We were already thinking about discharge planning. She was as good as gone, another thankful recipient of our expert diagnostic acumen.

Unfortunately, the cart was way in front of the horse. On further questioning, the patient's medical history was very significant for follicular lymphoma, post multiple rituximab treatment. The underrated but all-essential physical exam demonstrated lung crackles bilaterally. This was looking less and less like Lyme disease. The tick bite was starting to take on an ichthyoid aroma. And not just any kind of fish. It smelled like a red herring.

(Side note: Herring was once used by the English to train young scent hounds. Smoked herring, which turns red, was dragged through the woods to teach the hounds to ignore other smells and follow only the scent of game. Thus the term “red herring” is used to describe a distracting clue that draws attention away from a central issue or problem. Red herrings may often lead to another journey: the wild goose chase.)

So what was the final diagnosis? As you may have surmised, the Lyme serologies came back negative. There was no evidence of Ehrlichia; Anaplasma was absent; the patient was barren of Babesia. The fever was likely due to pneumonia. However, this was no “horse's hoofbeat” pneumonia; it was the sound of a true zebra. The organism was eventually identified as the gram-positive soil bacterium Actinomyces.

In the end, while on a wild goose chase for an arachnid vector, we came across a zebra. We learned that television, no matter how unbelievable, may be more like reality then we ever thought possible. And finally, we learned that a deer tick may really be a red herring.