WBR0057

Author	PageAuthor::William J Gibson
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Dermatology, SubCategory::Infectious Disease
Prompt	[[Prompt::A 39-year-old woman presents to her primary care physician complaining of fever, muscle soreness, headache and severe malaise one week after returning from a summer vacation on Cape Cod. Physical exam is significant for a red rash on her leg with an inner ring clearing resembling a bullseye. What is the most likely causal organism?]]
Answer A	AnswerA::Borrelia Burgdorferi
Answer A Explanation	[[AnswerAExp::Correct: Borrelia burgdorferi causes Lyme disease.]]
Answer B	AnswerB::Rickettsia Rickettsii
Answer B Explanation	AnswerBExp::'''Incorrect:''' Rickettsia Rickettsii causes Rocky Mountain Spotted Fever
Answer C	AnswerC::Coxiella burnetii
Answer C Explanation	[[AnswerCExp::Incorrect: Coxiella burnetii causes Q Fever.]]
Answer D	AnswerD::Brucella species
Answer D Explanation	[[AnswerDExp::Incorrect: Brucella causes undulant fever.]]
Answer E	AnswerE::Francisella Tularensis
Answer E Explanation	[[AnswerEExp::Incorrect: Francisella tularensis causes tularemia.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient in this vignette has the early stages of Lyme disease caused by the spirochete Borrelia burgdorferi. Borrelia burgdorferi is a zoonotic bacteria that is carried by the Ixodes tick. In its early stages, Lyme disease causes flu-like symptoms and a characteristic “bullseye” rash called erythema chronicum migrans in 80% of patients. The incubation period of Lyme disease can vary greatly, but is typically 1 to 2 weeks. If untreated, Lyme disease can cause facial palsy and AV nodal block (secondary Lyme disease) progressing to chronic monoarthritis or migratory polyarthritis (tertiary Lyme disease). Educational Objective: Lyme disease is caused by the organism Borrelia burgdorferi. References: First Aid 2014 page 141 Note: This question is linked to WBR0058 and WBR0059 Educational Objective: References: ]]
Approved	Approved::Yes
Keyword	WBRKeyword::Microbiology, WBRKeyword::Zoonotic, WBRKeyword::Animal, WBRKeyword::Tick, WBRKeyword::Lyme disease, WBRKeyword::Lyme, WBRKeyword::Bacteria, WBRKeyword::Rash, WBRKeyword::Dermatology, WBRKeyword::Linked
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::