View source for WBR0777

 {{WBRQuestion
|QuestionAuthor= {{SSK}} (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|MainCategory=Microbiology, Pathophysiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology, Pathophysiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology, Pathophysiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology, Pathophysiology
|MainCategory=Microbiology, Pathophysiology
|MainCategory=Microbiology, Pathophysiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology, Pathophysiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology, Pathophysiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology, Pathophysiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology, Pathophysiology
|MainCategory=Microbiology, Pathophysiology
|SubCategory=Infectious Disease
|Prompt=A 23-year-old man presents to the clinic for an unusual looking rash he first noticed this morning. He explains that although the rash feels slightly warmer than the surrounding skin, it is neither itchy nor painful. The patient denies any recent trauma or insect bites. He reports that he just returned from a vacation on the northeastern coast where he spent his time hiking and deer hunting. Otherwise, the patient denies any fatigue, chills, fever, headaches, myalgia or joint pain. On physical exam you notice the lesion shown below.  What would you expect the patient to develop after six months, if he were left untreated for his condition?

[[Image:WBR0777.jpg]]
|Explanation=Lyme disease is a systemic animal-borne illness caused by the spirochete Borrelia burgdorferi transmitted by the Ixodes tick. The disease typically affects the skin, nervous system, musculoskeletal system and heart. The disease is mostly seen in the northeastern United States. The states with the highest incidence of lyme disease include Massachusetts, Pennsylvania, and New York. Classically the disease has 3 phases. The initial phase involves a typical rash known as erythema migrans that expands forming a bull's eye pattern with central clearing. The first stage occurs between 2-20 days after the initial tick bite and inoculation. The second stage is characterized by neurologic manifestations including meningitis, AV nodal block, and Bell's palsy usually occurring several weeks after the inital bite. The final phase, occurring several months to years after the inital exposure, is characterized by chronic monoarthritis and migratory polyarthritis with associated cutaneous manifestations. Treatment is usually with doxycyline or ceftriaxone.
|AnswerA=Bell’s palsy
|AnswerAExp=Bell's palsy usually occurs several weeks after the initial tick bite.
|AnswerB=Third degree heart block
|AnswerBExp=AV nodal blocks also occurs several weeks after the initial tick bite.
|AnswerC=Recurrence of the same rash
|AnswerCExp=The same erythema migrans rash can occur within a few weeks after the initial tick bite.
|AnswerD=Meningitis
|AnswerDExp=Meningitis also occurs several weeks after the initial tick bite.
|AnswerE=Arthritis with severe joint swelling
|AnswerEExp=Chronic monoarthritis and migratory polyarthritis is a typical manifestation of late Lyme disease occurring several months to years after the initial tick bite.
|EducationalObjectives=Several months after the initial inoculation of Borrelia burgdorferi, the most common clinical manifestation of untreated Lyme disease is chronic monoarthritis and migratory polyarthritis.
|References=Biesiada G, Czepiel J, Leśniak MR, Garlicki A, Mach T. Lyme disease: review. Arch Med Sci. 2012;8(6):978-82.
|RightAnswer=E
|WBRKeyword=Lyme disease, Borrelia burgdorferi, Erythema migrans, Migratory polyarthritis
|Approved=Yes
}}