View source for WBR0548

 {{WBRQuestion
|QuestionAuthor= {{SSK}}  {{Alison}} (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|Prompt=A 33-year-old woman who recently immigrated from Brazil presents for two months of slowly increasing shortness of breath. She reports easy fatigability lately, and several episodes of lower-extremity edema. The patient also complains of two weeks of severe dysphagia and retrosternal chest pain following every meal. She is afraid to eat and has lost approximately 10 pounds. Physical examination reveals jugular venous distension, fine basal crackles, and an S3 gallop. Chest X-ray is unremarkable except for minor congestion. Echocardiography shows a dilated left ventricle with EF of 25%. Barium swallow done to evaluate her dysphagia is shown below. If the patient's disease is infectious in origin, which of the following vectors is most likely responsible?

[[Image:WBR0548.jpg|300px]]
|Explanation=[[Chagas disease]] is caused by the parasite ''[[Trypanosoma cruzi]]''. ''[[Trypanosoma cruzi]]'' is commonly transmitted by "kissing bugs" of the Reduviidae family (Reduviid bugs). [[Chagas disease]] is characterized by two stages of illness, acute and chronic. Although the acute stage is frequently asymtomatic, the chronic stage affects the nervous, digestive, and cardiovascular systems. The chronic stage is characterized by dilation of several hollow organs, resulting in megacolon, megaureter, megaesophagus ([[Chagas disease]] secondary achalasia with characteristic bird-beak appearance seen on barium swallow), and dilated cardiomyopathy. Treatment of [[Chagas disease]] is often with [[nifurtimox]]. [[Chagas disease]] usually manifests in Central America. Diagnosis of [[Chagas disease]] is determined upon serologies and observation of parasite amastigotes on blood smear.
|AnswerA=Sandfly
|AnswerAExp=Sandfly bites can transmit ''[[Leishmania donovani]]'', which causes Kala-azar.
|AnswerB=Reduviid Bug
|AnswerBExp=The Reduviid bug is responsible for transmitting ''[[Trypanosoma cruzi]]'', the causative agent of [[Chagas disease]].
|AnswerC=Ixodes tick
|AnswerCExp=The Ixodes tick transmits babesiosis (''[[Babesia microti]]'') and lyme disease (''[[Borrelia burgdorferi]]'').
|AnswerD=Anophelus mosquito
|AnswerDExp=The Anophelus mosquito transmits ''[[Plasmodium]]'' species, the causative agents of malaria.
|AnswerE=Horse fly
|AnswerEExp=The horse fly can transmit a parasitic filarial worm, known as Loa Loa.
|EducationalObjectives=[[Chagas disease]] is caused by the parasite ''[[Trypanosoma cruzi]]'' and is transmitted by Reduviid bugs.
|References=Prata A. Clinical and epidemiological aspects of [[Chagas disease]]. Lancet Infect Dis. 2001;1(2):92-100.
|RightAnswer=B
|WBRKeyword=Chagas disease, Trypanosoma cruzi, achalasia, dilated cardiomyopathy, microbiology, transmission, spread, carrier,
|Approved=Yes
}}