WBR233

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology, MainCategory::Microbiology
Sub Category	SubCategory::Dermatology, SubCategory::Dermatology
Prompt	[[Prompt::A 20 year old male presents to the physician’s office for several skin lesion. The patient has recently arrived to USA from Iraq. Patient’s vital signs were within normal limits. On physical examination, the patient had red skin nodules and skin ulcers as shown in the figure below. Skin scraping with microscopic analysis and needle aspiration of tissue fluid from the margin were performed. Which of the following organisms would most likely be the causative agent for this patient’s condition? ]]
Answer A	AnswerA::Toxoplasma gondii
Answer A Explanation	[[AnswerAExp::Toxoplasma gondii is a parasitic infection significant in utero and in HIV patients. Skin lesions are not characteristic findings of toxoplasmosis. The parasite cysts are found in meat and cat feces.]]
Answer B	AnswerB::Trypanosoma brucei
Answer B Explanation	[[AnswerBExp::Trypanosoma brucei is the causative agent of African sleeping sickness, transmitted by the Tse Tse fly. The disease is characterized by somnolence, lymphadenopathy and recurrent fever. Winterbottom’s sign is seen in early trypanosomiasis; it is characterized by swollen lymph along the back of the neck.]]
Answer C	AnswerC::Leishmania aethiopica
Answer C Explanation	AnswerCExp::Diagnosis of cutaneous leishmaniasis is based on physical examination findings of characteristic non-healing scaling lesions that frequently ulcerate.
Answer D	AnswerD::Loa loa
Answer D Explanation	[[AnswerDExp::Loa loa is nematode often called “eye worm”. It rests in the subcutaneous layer of the skin. Larvae grow in horseflies, such as deer flies and yellow flies.]]
Answer E	AnswerE::Paragonimus westermani
Answer E Explanation	[[AnswerEExp::Paragonimus westermani is a trematode that is also called the “lung fluke”. It is ingested in undercooked crab meat. It often causes a sub-acute or chronic lung disease and hemoptysis. Disseminated disease can spread to spinal cord and cause paralysis.]]
Right Answer	RightAnswer::C
Explanation	[[Explanation::Leishmaniasis has a spectrum of cutaneous, mucocutaneous, and visceral manifestations. Cutaneous leishmaniasis is a parasitic disease characterized by multiple skin ulcerations. The disease is spread by the bite of sand flies. Diagnosis of cutaneous leishmaniasis is based on physical examination findings of characteristic non-healing scaling lesions that frequently ulcerate. The disease is endemic to several regions of the world, most commonly the Middle East region in Afghanistan, Algeria, Iran, Iraq, Saudi Arabia, and Syria and in the South American region in Brazil and Peru. Treatment of cutaneous leishmaniasis is pentavalent antimonials, such as sodium stibogluconate (Pentostam) and local care of ulcerating lesions that may be exposed to bacterial super-infections, commonly staphylococcus aureus. Educational Objective: Cutaneous leishmaniasis is a common form of leishmaniasis characterized by ulcerating red lesions. It is endemic to Middle East and South America. The causative organism is leishmania. Sodium stibogluconate is an available treatment for cutaneous leishmaniasis. References: Markle WH, Makhoul K. Cutaneous leishmaniasis: Recognition and Treatment. Am Fam Physician. 2004; 15;69(6):1455-1460]]
Approved	Approved::Yes
Keyword	WBRKeyword::Microbiology, WBRKeyword::Parasites, WBRKeyword::Skin ulcer, WBRKeyword::Skin lesion, WBRKeyword::Zoonotic infection
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