Tick bites, Lyme disease, and a Tale of Three Patients - ConvenientMD

Tick bites, Lyme disease, and a Tale of Three Patients




Last week a young man in his twenties presented at ConvenientMD Urgent Care with a rash on his leg. It wasn’t a classic bull’s eye Lyme rash, which we call erythema migrans (see the photo below), but it was definitely two-toned. He was worried about Lyme disease. What the patient didn’t realize was that after a complete exam was done, five classic erythema migrans lesions were discovered on his back. The patient never recalled being bitten by a tick.erythema migrans

A few days later a five year old boy presented with a grossly swollen left knee. He’d been playing in the park and mom or dad couldn’t recall if he’d fallen or not, although he had several bumps and bruises. He had a low grade fever and a dense knee effusion but not much else on exam. Mom was concerned about juvenile arthritis. He had no history of a tick bite.

The final patient was a pleasant woman in her late 30’s who had a tick attached to her back, right between her shoulders blades. Her husband removed it and the patient brought it in with here, concerned again about Lyme disease.

We see lots of tick bites in the Urgent Care. We also see lots of other insect bites, lots of rashes, and lots of people with symptoms that include fever and chills, headache, muscle and joint aches, fatigue and enlarged lymph nodes. Sorting out what may or may not be Lyme disease is where the clinical skill comes in. Our first young man has “early disseminated” Lyme disease with multiple erythema migrans lesions. This can occur days to weeks after a tick bite. He was immediately started on a 21 day course of antibiotics. (Physicians debate the proper length of antibiotic treatment, like we debate many aspects of Lyme disease.) Note that a Lyme antibody blood test would be of very limited value in this patient. His rash is classic for Lyme disease or as we say “pathognomonic” so he needs to be treated no matter what his antibody test shows, as he may or may not have seroconverted (that is, developed antibodies) at this point.

Our young five year old boy was more complicated. A tense joint effusion with no history or sign of trauma is worrisome for many conditions ranging from infection to different types of arthritis to cancer. He had a thorough exam, a complete blood count, a sedimentation rate, and a Lyme test. His Lyme test came back positive. He also had “early disseminated” Lyme disease and was prescribed a three week course of antibiotics and close follow up with his pediatrician.

Note that “early localized” Lyme disease may present as a single erythema migrans rash where the tick bite occurred and is found in 60-80% of people three to thirty days after a deer tick bite on average. Patients may also present with fever, chills, fatigue, body aches, joint aches, headaches, and swollen lymph nodes. With “early disseminated” disease the patient might have multiple EM lesions on other parts of their body, like our first patient, but also may have a Bells’ palsy with one sided facial drooping, severe headaches and even neck stiffness if meningitis is present, pain and swelling in the larger joints (like our young boy with the swollen knee), and even heart palpitations and dizziness. “Late disseminated stage” Lyme disease and “post-treatment Lyme disease syndrome” are beyond the scope of this current blog but we’re happy to discuss these entities with you.

Our third patient showed me her tick. On gross microscopy I could easily tell it was a common dog tick and not an Ixodes scapularis deer tick. On further questioning she stated she slept with her two dogs. If it was a deer tick and the tick was attached for 36 or more hours I would consider antibiotic prophylaxis with a single dose of doxycycline, but even this is a debated treatment point. She wouldn’t benefit from Lyme testing.

Three patients, two with Lyme disease and no known tick bites, one with a tick bite and no known Lyme disease. Practicing in the Lyme endemic area of southern New Hampshire is always interesting!

Jeffrey Collins, MD
Medical Director,
ConvenientMD Urgent Care