CASE 27
Arnold, a 28-year-old man, recently returned from a camping trip in Massachusetts and has noticed several large, itchy, erythematous (red) patches (that seem to “move around”) on his arms. He remembers being bitten by some “bugs” while camping, but otherwise there is no significant medical history of note and no drug history. You recall reading about Lyme disease while you were at medical school and order a serum test for antibodies to Borrelia burgdorferi. The test comes back positive, confirming your suspicions (and the recognition of a classic “erythema migrans” picture).
QUESTIONS FOR GROUP DISCUSSION
RECOMMENDED APPROACH
Implications/Analysis of Clinical History
Sixty to 80 percent of patients infected with B. burgdorferi initially develop a red spot that expands to form the characteristic ring shape with an outer red shape with a clear center, often described as “bull’s-eye” in appearance. Doxycycline is the treatment of choice for men and nonpregnant women and appeared to be effective for Arnold. However, the later presentation of arthritis and the fact that there was no obvious resolution of the arthritic picture suggests that bacterial persistence is not likely the cause of the arthritis. Patients who fail therapy continue to have reactivity to B. burgdorferi outer surface lipoprotein A (OspA), suggesting that this antigen cross reacts with a host protein.