Communicable diseases: parous rate of Anopheles: 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.

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PSM · Communicable diseases: parous rate of Anopheles

Sample item

In an area under malaria surveillance, an entomologist dissects the ovaries of wild-caught female Anopheles to classify them as nulliparous or parous. What does the proportion of parous females help to estimate?

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

The answer and the reasoning

D. Longevity of the vector, which governs its transmission capacity

Ovarian dissection shows whether a female has laid eggs. The parous rate gives an estimate of the daily survival and longevity of the vector, which is critical because the parasite needs the mosquito to live long enough to complete sporogony. Sporozoite rate is measured by dissecting salivary glands.

Option by option

  • A. Resistance of the vector to common insecticides

    Insecticide resistance is tested by susceptibility bioassays, not by examining ovaries.

  • B. Proportion of vectors carrying sporozoites

    The sporozoite rate is obtained by examining salivary glands or by laboratory assays.

  • C. Man-biting rate of the vector population

    The man-biting rate is estimated by human landing or bait catches, not by ovarian dissection.

  • D. Longevity of the vector, which governs its transmission capacity (correct)

    Correct. The parous rate reflects how long females survive, which determines transmission potential.

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.

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Questions about this PSM question

What is the answer to this PSM question?

The best answer is D, Longevity of the vector, which governs its transmission capacity. Ovarian dissection shows whether a female has laid eggs.

Why is "Resistance of the vector to common insecticides" not the answer?

Insecticide resistance is tested by susceptibility bioassays, not by examining ovaries.

Why is "Proportion of vectors carrying sporozoites" not the answer?

The sporozoite rate is obtained by examining salivary glands or by laboratory assays.

Why is "Man-biting rate of the vector population" not the answer?

The man-biting rate is estimated by human landing or bait catches, not by ovarian dissection.

What concept does this question test?

It tests Communicable diseases: parous rate of Anopheles in PSM. The parous rate gives an estimate of the daily survival and longevity of the vector, which is critical because the parasite needs the mosquito to live long enough to complete sporogony. Sporozoite rate is measured by dissecting salivary glands.

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 Communicable diseases: parous rate of Anopheles?

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.