WBR0084

Author	PageAuthor::Kalsang Dolma (Reviewed by Rim Halaby and Will Gibson)
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::General Principles
Prompt	[[Prompt::A 28-year-old female immigrant from Africa presents with complaints of an itchy swelling over her entire body and body aches. On physical examination, non-tender swelling is noted over her right arm and leg. Laboratory tests are remarkable for eosinophilia. The diagnosis is confirmed when microscopic examination of the blood shows microfilaria of loa loa. Which of the following is the most likely vector for this condition?]]
Answer A	AnswerA::Black fly
Answer A Explanation	[[AnswerAExp::The black fly is the vector for onchocerciasis.]]
Answer B	AnswerB::Soft tick
Answer B Explanation	[[AnswerBExp::The soft tick is a vector for relapsing fever.]]
Answer C	AnswerC::Hard tick
Answer C Explanation	[[AnswerCExp::The hard tick refers to a family of ticks including the Dermacentor and Ixodes ticks. Hard ticks are the vectors for lyme diseae, rocky mountain spotted fever, babesiosis, ehrlichiosis, tick-borne meningoencephalitis, colorado tick fever, Crimean-Congo hemorrhagic fever, and tick paralysis.]]
Answer D	AnswerD::Deerfly
Answer D Explanation	[[AnswerDExp::Deerfly is the vector for loa loa.]]
Answer E	AnswerE::Sandfly
Answer E Explanation	[[AnswerEExp::Sandfly is the vector for leishmaniasis.]]
Right Answer	RightAnswer::D
Explanation	[[Explanation::The deerflies (genus Chrysops) that transmit Loa loa bite during the day. Most people with loiasis do not experience signs or symptoms of infection, though persons who do not live in areas where the parasite is found, such as travelers to the area, are more likely to experience them. The most common manifestations of the disease are Calabar swellings and eye worm. Calabar swellings are localized, non-tender swellings usually found on the limbs and near joints. They are associated with itching that occurs in the area of the swelling or is generalized to the large areas of the body. Eye worm is the visible migration of the adult worm across the surface of the eye. Eye worm can be accompanied by eye congestion, itching, pain, and light sensitivity. Although eye worm can be very distressing, it usually lasts less than one week (often just hours) and typically causes minimal damage to the eye. Other manifestations of disease include generalized itching, hives, muscle pains, joint pains, fatigue, and adult worms visibly migrating under the surface of the skin. Increased numbers of eosinophils are usually found on blood tests. Persons with long-term infection might develop kidney damage through immune complex deposition, though progression to chronic kidney disease is not common. Other uncommon manifestations include inflammation of the lymph glands, scrotal swellings, and lung infiltrates along with collections of fluid around the lung. Loiasis may also be associated with scarring of heart muscle. Educational Objective: Deerlies transmit the infectious organism loa loa that causes loiasis, a disease characterized by Calabar swellings and eye worm. References: First Aid 2014 page 154, CDC page]]
Approved	Approved::Yes
Keyword	WBRKeyword::Loa Loa, WBRKeyword::Infectious disease, WBRKeyword::Deerfly, WBRKeyword::Deerflies, WBRKeyword::eye worm, WBRKeyword::Worm, WBRKeyword::Zoonotic, WBRKeyword::Microbiology, WBRKeyword::Vector
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Order in Linked Questions	LinkedOrder::