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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor= {{SSK}} {{Alison}} (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Microbiology
|MainCategory=Microbiology
Line 8: Line 8:
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|SubCategory=Infectious Disease
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
Line 20: Line 21:
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Infectious Disease
|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 when she eats. She is afraid to eat and has lost 10 pounds. Physical exam shows jugular venous distension, fine basal crackles, and an S3 gallop. Chest X-ray is unremarkable except for minor congestion. Echocardiography reveals dilated left ventricle with EF of 30%. Barium swallow done to evaluate her dysphagia is shown below. If the patient's disease is infectious in origin, which of the following vectors are most likely responsible?
|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:Birdbeak.png|500px]]
|Explanation=Chagas disease is caused by the parasite Trypanosoma cruzi. T. cruzi is commonly transmitted via a painless bite to humans and other mammals by "kissing bugs" of the family Reduviidae or simply Reduviid bugs. Chagas disease has 2 illness stages: acute and chronic. Although the acute stage is usually asymtomatic, the chronic stage affects the nervous system, digestive system and heart. It is characterized by dilation of several hollow organs causing megacolon, megaureter, megaesophagus (Chagas disease also causes secondary achalasia with characteristic bird-beak appearance seen on barium swallow), and dilated cardiomyopathy. Treatment is usually with nifurtimox although of little benefit in the chronic stage. Chagas disease is mostly seen in Central America. Diagnosis is by serologies and by visualizing the parasite amastigotes on blood smear.
 
Educational objective: Chagas disease is caused by the parasite Trypanosoma cruzi transmitted by a painless bite from the Reduviid bug.


References:
[[Image:WBR0548.jpg|300px]]
Prata A. Clinical and epidemiological aspects of Chagas disease. Lancet Infect Dis. 2001;1(2):92-100.
|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
|AnswerA=Sandfly
|AnswerAExp=The sandfly bite is responsible for transmitting Leishmania donovani that causes Kala-azar.
|AnswerAExp=Sandfly bites can transmit ''[[Leishmania donovani]]'', which causes Kala-azar.
|AnswerB=Reduviid Bug
|AnswerB=Reduviid Bug
|AnswerBExp=The Reduviid bug is responsible for transmitting Trypanosoma cruzi the causative agent of Chagas disease whose chronic stage presents similar to our patient.
|AnswerBExp=The Reduviid bug is responsible for transmitting ''[[Trypanosoma cruzi]]'', the causative agent of [[Chagas disease]].
|AnswerC=Ixodes tick
|AnswerC=Ixodes tick
|AnswerCExp=The Ixodes tick is responsible for causing babesiosis (Babesia microti) and lyme disease (Borrelia burgdorferi).
|AnswerCExp=The Ixodes tick transmits babesiosis (''[[Babesia microti]]'') and lyme disease (''[[Borrelia burgdorferi]]'').
|AnswerD=Anophelus mosquito
|AnswerD=Anophelus mosquito
|AnswerDExp=The Anophelus mosquito is responsible for transmitting Plasmodium species the causative agents of malaria.
|AnswerDExp=The Anophelus mosquito transmits ''[[Plasmodium]]'' species, the causative agents of malaria.
|AnswerE=Horse fly
|AnswerE=Horse fly
|AnswerEExp=The horse fly usually transmits a parasitic filarial worm known as Loa Loa.
|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
|RightAnswer=B
|WBRKeyword=Chagas disease, Trypanosoma cruzi, achalasia, dilated cardiomyopathy
|WBRKeyword=Chagas disease, Trypanosoma cruzi, achalasia, dilated cardiomyopathy, microbiology, transmission, spread, carrier,
|Approved=No
|Approved=Yes
}}
}}

Latest revision as of 00:55, 28 October 2020
Author [[PageAuthor::Serge Korjian M.D. (Reviewed by Alison Leibowitz) (Reviewed by Serge Korjian)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Microbiology
Sub Category SubCategory::Infectious Disease
Prompt [[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?

]]

Answer A AnswerA::Sandfly
Answer A Explanation [[AnswerAExp::Sandfly bites can transmit Leishmania donovani, which causes Kala-azar.]]
Answer B AnswerB::Reduviid Bug
Answer B Explanation [[AnswerBExp::The Reduviid bug is responsible for transmitting Trypanosoma cruzi, the causative agent of Chagas disease.]]
Answer C AnswerC::Ixodes tick
Answer C Explanation [[AnswerCExp::The Ixodes tick transmits babesiosis (Babesia microti) and lyme disease (Borrelia burgdorferi).]]
Answer D AnswerD::Anophelus mosquito
Answer D Explanation [[AnswerDExp::The Anophelus mosquito transmits Plasmodium species, the causative agents of malaria.]]
Answer E AnswerE::Horse fly
Answer E Explanation AnswerEExp::The horse fly can transmit a parasitic filarial worm, known as Loa Loa.
Right Answer RightAnswer::B
Explanation [[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.

Educational Objective: 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.]]

Approved Approved::Yes
Keyword WBRKeyword::Chagas disease, WBRKeyword::Trypanosoma cruzi, WBRKeyword::achalasia, WBRKeyword::dilated cardiomyopathy, WBRKeyword::microbiology, WBRKeyword::transmission, WBRKeyword::spread, WBRKeyword::carrier
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