Onchocerciasis (river blindness) is transmitted by the black fly. The characteristic breeding habitat of the Simulium vector that gives the disease its name is:

• A Stagnant ponds rich in organic matter
• B Fast-flowing, well-oxygenated streams and rivers ✓
• C Tree holes and bamboo stumps holding rainwater
• D Water stored in domestic containers

Explanation

Simulium damnosum females deposit eggs on vegetation and rocks in rapidly flowing, oxygen-rich water; the larvae attach to submerged substrates in these rapids. This strict ecological requirement explains why disease clusters along river valleys, hence the term river blindness, and why dam spillways created new foci. Stagnant and container habitats belong to Culex, Aedes and Mansonia instead.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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