What type of fly transmits the helminthic infection known as River Blindness?

The correct choice is the black fly, which is known for its role in the transmission of the parasitic infection onchocerciasis, commonly referred to as River Blindness. This disease is caused by the filarial worm Onchocerca volvulus, which resides in the human body and can lead to severe eye problems, including blindness. The black fly serves as a vector by biting and ingesting larvae from infected individuals; when the flies bite again, they can introduce these larvae into the bloodstream of new hosts.

Understanding the lifecycle of the black fly is essential to recognizing its role in disease transmission. These insects typically breed in fast-flowing rivers and streams, which is why the disease is often found in areas near such water bodies. This geographic association links the ecology of the black fly to the spread of River Blindness, explaining why controlling black fly populations is a key focus in efforts to manage and prevent the disease.