**Question:** Tse-tse fly transmits -

A. Trypanosomiasis (African sleeping sickness)
B. Leishmaniasis
C. Leprosy
D. Malaria

**Core Concept:** Tse-tse fly (Glossina morsitans) is a common species of blood-sucking fly found in sub-Saharan Africa, known for transmitting Trypanosoma brucei gambiense, which causes African sleeping sickness or Trypanosomiasis.

**Why the Correct Answer is Right:** Tse-tse flies become infected with Trypanosoma brucei gambiense when they feed on infected mammals, mainly rodents and primates. The parasite enters the fly's digestive system, multiplies, and eventually reaches the fly's salivary glands. When the fly bites a new host, it injects the parasite into the host's bloodstream, causing Trypanosomiasis or African sleeping sickness.

**Why Each Wrong Option is Incorrect:**

A. Trypanosomiasis (African sleeping sickness) is NOT transmitted by tse-tse flies; it is primarily transmitted by other species like tsetse flies and blood-sucking mosquitoes.
B. Leishmaniasis is a group of infections caused by protozoan parasites of the Leishmania genus, transmitted through the bite of sandflies.
C. Leprosy is caused by Mycobacterium leprae and Mycobacterium lepromatosis, transmitted through the skin or mucous membranes following direct contact with an infected person or animal.
D. Malaria is caused by Plasmodium parasites transmitted through the bite of infected Anopheles mosquitoes, not tse-tse flies.

**Clinical Pearl:** Understanding the vector-borne transmission of diseases is essential for clinical practice and public health strategies, especially in endemic regions. Proper knowledge of vector species, their habitats, and transmission routes can guide preventive measures and infection control.