WBR0057
| Author | PageAuthor::William J Gibson |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Microbiology |
| Sub Category | |
| Prompt | [[Prompt::A 39 year old woman presents to your office complaining of fever, muscle soreness, headache and severe malaise one week after returning from a summer vacation on Cape Cod. She shows you a red rash on her leg with a inner ring clearing resembling a bullseye. What is the causal organism?]] |
| Answer A | AnswerA::Borrelia Burgdorferi |
| Answer A Explanation | AnswerAExp::Correct - Borrelia Burgdorferi causes Lyme disease. See explanation. |
| 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. Lyme disease is caused by the organism Borrelia Burgdorferi, a bacteria which is carried by the Ixodes tick. In its early stages, Lyme disease causes a characteristic “bullseye” rash called erythema chronicum migrans in 80% of patients. Most patients exhibit flu-like symptoms in the early stages of infection. 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 2012 page 165.
Tags: #Microbiology #Pathophysiology |
| Approved | Approved::Yes |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |