Communicable diseases: Japanese encephalitis ecology: practice question

A PSM 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.

Try it

PSM · Communicable diseases: Japanese encephalitis ecology

Sample item

Several children in a rice-growing village with many pig farms present with fever, convulsions and altered sensorium during the monsoon. Which animal acts as the main amplifying host of the causative virus?

APigsBHorsesCHumansDDogs

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

The answer and the reasoning

A. Pigs

In Japanese encephalitis the virus is maintained in a cycle between Culex mosquitoes (Culex tritaeniorhynchus) and ardeid water birds, and pigs act as amplifier hosts, developing high viraemia without illness. Humans and horses are dead-end hosts with low viraemia. Siting pigsties away from houses and vaccinating in endemic districts help control it.

Option by option

A. Pigs (correct)
Correct. Pigs develop prolonged high-titre viraemia and infect mosquitoes.
B. Horses
Horses are dead-end hosts and do not generate enough viraemia to infect mosquitoes.
C. Humans
Humans are accidental dead-end hosts, with viraemia too low to infect mosquitoes.
D. Dogs
Dogs are not a recognised reservoir or amplifier of Japanese encephalitis virus.

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 PSM question

What is the answer to this PSM question?

The best answer is A, Pigs. In Japanese encephalitis the virus is maintained in a cycle between Culex mosquitoes (Culex tritaeniorhynchus) and ardeid water birds, and pigs act as amplifier hosts, developing high viraemia without illness.

Why is "Horses" not the answer?

Horses are dead-end hosts and do not generate enough viraemia to infect mosquitoes.

Why is "Humans" not the answer?

Humans are accidental dead-end hosts, with viraemia too low to infect mosquitoes.

Why is "Dogs" not the answer?

Dogs are not a recognised reservoir or amplifier of Japanese encephalitis virus.

What concept does this question test?

It tests Communicable diseases: Japanese encephalitis ecology in PSM. Humans and horses are dead-end hosts with low viraemia. Siting pigsties away from houses and vaccinating in endemic districts help control it.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Communicable diseases: Japanese encephalitis ecology?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM 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.