Which fly genus transmits Trypanosoma spp., causing sleeping sickness and Nagana?

• A. Drosophila melanogaster
• B. Muscina domestica
• C. Glossina spp. (tsetse fly)
• D. Anopheles gambiae

Answer: (C)

The main idea is biological vector transmission of African trypanosomiasis. Only Glossina, the tsetse fly, serves as a competent biological vector for Trypanosoma species that cause sleeping sickness in humans and Nagana in animals. When a tsetse fly bites an infected mammal, the parasites develop inside the fly and migrate to its salivary glands. On a later bite, metacyclic trypomastigotes are injected into a new host, starting infection. This internal development in the insect is what makes transmission possible, setting Glossina apart from other flies. Drosophila melanogaster is a fruit fly and not a Trypanosoma vector, Anopheles gambiae transmits malaria, and Muscina domestica can carry some pathogens mechanically but is not a known transmitter of trypanosomes.