Phlebotomus argentipes is the vector for visceral leishmaniasis (Kala-azar) in India. Which characteristic of this sandfly makes indoor residual spraying (IRS) with DDT effective as the primary vector control measure?

• A P. argentipes is a diurnal feeder and rests outdoors on tree bark
• B P. argentipes breeds in stagnant water collections, which are eliminated by IRS
• C P. argentipes is exclusively zoophilic and IRS targets animal sheds only
• D P. argentipes rests indoors on walls and has low flight capacity, making indoor spraying highly effective ✓

Explanation

Phlebotomus argentipes, the sandfly vector of Leishmania donovani, has characteristic endophilic (indoors resting) behaviour and limited flight capacity (rarely flies more than 50–200 metres). It rests on indoor walls, floors, and dark moist surfaces. This makes IRS with DDT or synthetic pyrethroids highly effective—the sandfly contacts the insecticide on resting surfaces. Breeding occurs in moist organic soil/leaf litter and debris, not stagnant water (which is relevant for mosquito control). Its crepuscular/nocturnal biting pattern means bed nets also provide protection.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.