Parasitology: chronic Chagas disease pathogenesis: practice question

A Microbiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Microbiology · Parasitology: chronic Chagas disease pathogenesis

Sample item

A 45-year-old man from rural Latin America has dysphagia with a dilated oesophagus, chronic constipation with megacolon and dilated cardiomyopathy. Which process underlies the visceral dilatation?

AMechanical obstruction by encysted larvae in the bowel wallBGranuloma fibrosis around eggs trapped in the bowel wallCA circulating toxin paralysing visceral smooth muscleDLoss of intramural autonomic neurons from parasite-driven inflammation

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Loss of intramural autonomic neurons from parasite-driven inflammation

In chronic Chagas disease, parasite persistence and immune-mediated damage destroy intramural ganglion cells of the oesophagus and colon, causing megaoesophagus and megacolon. Similar damage and inflammation in the heart produce cardiomyopathy and conduction defects.

Option by option

A. Mechanical obstruction by encysted larvae in the bowel wall
Chagas disease does not involve encysted larvae obstructing the gut.
B. Granuloma fibrosis around eggs trapped in the bowel wall
Granulomas around eggs describe schistosomiasis, not American trypanosomiasis.
C. A circulating toxin paralysing visceral smooth muscle
No circulating toxin is responsible; the damage is from parasites and immune injury to neurons.
D. Loss of intramural autonomic neurons from parasite-driven inflammation (correct)
Correct. Neuronal loss in the enteric plexuses causes the megaviscera of chronic Chagas disease.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is D, Loss of intramural autonomic neurons from parasite-driven inflammation. In chronic Chagas disease, parasite persistence and immune-mediated damage destroy intramural ganglion cells of the oesophagus and colon, causing megaoesophagus and megacolon.

Why is "Mechanical obstruction by encysted larvae in the bowel wall" not the answer?

Chagas disease does not involve encysted larvae obstructing the gut.

Why is "Granuloma fibrosis around eggs trapped in the bowel wall" not the answer?

Granulomas around eggs describe schistosomiasis, not American trypanosomiasis.

Why is "A circulating toxin paralysing visceral smooth muscle" not the answer?

No circulating toxin is responsible; the damage is from parasites and immune injury to neurons.

What concept does this question test?

It tests Parasitology: chronic Chagas disease pathogenesis in Microbiology. Similar damage and inflammation in the heart produce cardiomyopathy and conduction defects.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Parasitology: chronic Chagas disease pathogenesis?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.