Differential Diagnosis
- Single most likely diagnosis
- E) Remote exposure to B. burgdorferi, but no active Lyme disease: The patient's symptoms have persisted despite multiple courses of doxycycline, and the presence of IgM antibodies without IgG antibodies suggests a past infection rather than an active one. The lack of response to treatment and the absence of IgG antibodies make active Lyme disease less likely.
- Other Likely diagnoses
- B) Biologic false positive test: The patient's symptoms are non-specific and could be caused by various conditions. A false positive test result could lead to misdiagnosis and unnecessary treatment.
- C) Chronic Lyme disease: Although controversial, some patients may experience persistent symptoms after Lyme disease treatment. However, the lack of IgG antibodies and the patient's treatment history make this diagnosis less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- A) Active Lyme disease: Although less likely given the patient's treatment history and laboratory results, active Lyme disease can have serious consequences if left untreated, such as neurological or cardiac complications.
- Rare diagnoses
- D) No evidence of prior exposure to B. burgdorferi: This diagnosis is unlikely given the patient's history of a tick bite and positive serologic test results. However, it is possible that the patient's symptoms are unrelated to Lyme disease, and further evaluation may be necessary to rule out other conditions.
- Other rare diagnoses to consider include post-treatment Lyme disease syndrome (PTLDS), which is a condition characterized by persistent symptoms after Lyme disease treatment, and other tick-borne illnesses, such as babesiosis or anaplasmosis. However, these diagnoses are less likely given the patient's presentation and laboratory results.