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High Yield Notes
6 pages


7 flashcards

USMLE® Step 1 style questions USMLE

2 questions

USMLE® Step 2 style questions USMLE

1 questions

A 42-year-old man is brought to the emergency department because of a high fever which started 2 days ago. He appears acutely ill and reports that he has been feeling tired and short of breath, and has noticed his urine is darker than normal. His temperature is 38.7°C (101.6°F), pulse is 94/min, respirations are 22/min, and blood pressure is 95/60 mm Hg. His past medical history includes idiopathic thrombocytopenic purpura, for which he had a splenectomy. He has recently returned from a 2-week summer holiday to Tanzania. Laboratory studies show:

A peripheral blood smear shows an intraerythrocytic ring form and a ‘Maltese cross’ (tetrad) sign. Which of the following organisms is the most likely cause of this patient’s symptoms?

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External References
Babesia is a genus of protozoa that infect the blood and cause a parasitic, hemolytic disease known as babesiosis. Transmission is via the Ixodes tick, the same species that often carries Borrelia burgdorferi (the cause of Lyme disease), and thus coinfection with these two parasites may occur in a patient. The endemic region is the northeastern United States. People who contract babesiosis suffer from malaria-like symptoms, such as hemolytic anemia and fever. Individuals without a spleen are at increased risk for severe disease. Microscopic analysis may show a ring form or "maltese-cross" within red blood cells. Treatment is with Atovaquone and azithromycin.