Dysphagia Case 1

A 25-year-old woman consults a physician because she has developed severe dysphagia and constipation that has led to a recent weight loss of 15 pounds. She is referred to a gastroenterologist, to whom she reports that she has a great deal of trouble swallowing solid foods, but not liquids, and has also been having nearly constant gastroesophageal reflux symptoms. She has awakened during the night several times coughing and feeling as if she had aspirated acid stomach contents. Esophagogastroduodenoscopy and colonoscopy are performed, and demonstrate massive dilatation of the esophagus and colon.

Q 1
Which of the following parasitic diseases would most likely produce megaesophagus and megacolon?
/ A. Chagas disease
/ B. Cysticercosis
/ C. Hydatid disease
/ D. Malaria
/ E. Threadworm infection

Q2
The infecting species is which of the following?
/ A. Fluke
/ B. Nematode
/ C. Plasmodia
/ D. Tapeworm
/ E. Trypanosome

Q 3
On further questioning, the woman reports having lived for a year in Bolivia as a teenager. At one point, she had had an automobile accident and had been transfused with blood at a local hospital there. The person whose blood she received had probably acquired the infection via a
bite by which of the following?
/ A. Flea
/ B. Mosquito
/ C. Reduviid bug
/ D. Tick
/ E. Tsetse fly

Q4
While this woman's gastrointestinal tract disease brought her to medical attention, involvement of which of the following is the principal source of morbidity and mortality in this condition?
/ A. Heart
/ B. Kidneys
/ C. Liver
/ D. Lungs
/ E. Pancreas

Q 5
While no drug therapy is useful in the therapy of chronic cases, treatment can be used in newly diagnosed acute cases. Which of the following medications would be most useful in treating the acute infection?
/ A. Chloroquine
/ B. Doxycycline
/ C. Nifurtimox
/ D. Primaquine
/ E. Pyrimethamine-sulfadoxine

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Dysphagia case 1 answers
A1
The correct answer is A. Megaesophagus and megacolon are unusual pathologic changes, and should bring Chagas disease to mind, which is also known as American trypanosomiasis. Megacolon, but not megaesophagus, can also be due to Hirschsprung disease, but this is usually diagnosed in infants and young children and is due to abnormal neural development in the gut.
Cysticercosis (choice B) can cause cyst formation in the brain and other organs.
Hydatid disease (choice C) can cause cysts in the liver and other organs.
Malaria (choice D) can be complicated by fever, chills, anemia, splenomegaly, and in severe cases, renal failure, coma, thrombocytopenia, and respiratory distress syndrome.
Threadworm infection (choice E) can cause skin rashes, eosinophilia, abdominal pain, and, in severe cases, massive GI bleeding, severe malnutrition, and severe pulmonary symptoms

A2
The correct answer is E. Chagas disease is caused by infection with Trypanosoma cruzi, which is an intracellular protozoan parasite that takes a leishmanial form within muscle cells.
Examples of fluke (choice A) or trematode diseases include schistosomiasis (blood flukes), paragoniasis (lung fluke), and various liver flukes (e.g., clonorchiasis, fascioliasis, fasciolopsiasis).
Examples of nematode (choice B), or round worm diseases, include the various intestinal nematodes (e.g., ascariasis, trichuriasis, ancylostomiasis, strongyloidiasis), tissue nematodes (e.g., toxocariasis, trichinosis, dracunculosis), and the filarial nematodes (e.g., elephantiasis, onchocerciasis).
Plasmodia (choice C) cause malaria.
Tapeworm infections (choice D) include intestinal infections (diphyllobothriasis, Taenia infections), cysticercosis (due to Taenia solium), and Echinococcus infections.

A3
The correct answer is C. Reduviid bugs are insects that live in poorly constructed adobe housing and feed on human or animal blood. Trypanosomes they ingest during their feedings multiply in the insect gut and are deposited in fecal material near the wound when the insect bites another individual. Contamination through the wound leads to invasion into, and reproduction within, host cells. Release of the trypanosomes back into the blood stream makes them available for transmission either via another bug bite or via blood transfusion. Transmission of Chagas disease via blood transfusion has also become an important mode of transmission in South America. Santa Cruz, Bolivia is thought to have a prevalence of infected blood in blood banks of 53%, which is much higher than the rate of hepatitis or HIV infection. In other parts of South America, the infection rate is much lower, due primarily to a massive attempt by the World Health Organization to eliminate both the reduviid bug (through better housing and insecticide use) and screen for Chagas disease in blood products in endemic regions. These attempts have been most successful in eradicating or nearly eradicating the infection in Chile, Uruguay, and Brazil. Transmission of Chagas disease via blood transfusions has not been a significant problem in the United States, primarily because one of the questions asked before a blood donation is taken is whether or not a person has traveled outside the United States during the previous year. While Chagas disease can persist for decades, the period in which significant numbers of parasites are in the blood is usually only during the comparatively short (and often asymptomatic) acute phase of the illness.
Flea-borne illnesses (choice A) to remember include bubonic plague and typhus.
Associate mosquito bites (choice B) with malaria.
Associate tick bites (choice D) with Lyme disease, babesiosis, and Rocky Mountain spotted fever. Associate Tsetse fly bites (choice E) with African trypanosomiasis (sleeping sickness).

A4
The correct answer is A. Chagas disease is conventionally divided into three stages. The short acute period may be asymptomatic or may be characterized by fever, swelling of lymph glands, hepatosplenomegaly, and local inflammation at the site of the bite. This is followed by an asymptomatic period, which may last years to the rest of the patient's life. In one-third of patients, clinically evident disease becomes apparent 10-20 years after infection. 27% of infected patients develop cardiac symptoms (which may cause flaccid cardiomyopathy, cardiac aneurysm formation, or sudden death); 6% develop digestive system damage with megaviscera (thought to be related to neural involvement rather than muscle involvement); and 3% develop neural involvement. You should also be aware that coexisting AIDS infection may predispose for an unusually rapid and severe course of Chagas disease.
The kidneys (choice B), liver (choice C), lungs (choice D), and pancreas (choice E) are not particular targets in this disease.

A5
The correct answer is C. The diagnosis in suspected acute cases can be established with review of thin or thick blood smears. (The diagnosis in latent and chronic cases usually requires special blood culture techniques or PCR-amplified detection of parasite DNA in blood.) The only effective drugs are nifurtimox and benznidazole, which are given in courses up to 4 months because the organisms are difficult to eradicate. The other choices listed are drugs used in malaria prophylaxis or treatment.