Vector for Kala-azar –
**Core Concept**
Kala-azar, also known as visceral leishmaniasis, is a severe form of leishmaniasis caused by the protozoan parasite *Leishmania donovani*. The disease is transmitted through the bite of an infected female phlebotomine sandfly, which acts as the primary vector.
**Why the Correct Answer is Right**
The correct vector for Kala-azar is the sandfly, specifically species of *Phlebotomus* in the Old World and *Lutzomyia* in the New World. These sandflies acquire the parasite while feeding on the blood of infected mammals. When they feed on human blood, they transmit the parasite to the host, leading to the development of Kala-azar.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not mention the vector for Kala-azar. While *Leishmania donovani* is the causative agent of the disease, the question specifically asks for the vector.
**Option B:** This option is incorrect because it does not specify the correct genus or species of sandfly. While sandflies are the correct vectors, the question requires a more precise answer.
**Option C:** This option is incorrect because it does not mention the sandfly as the vector. Mosquitoes are vectors for other diseases, such as malaria and dengue fever, but not Kala-azar.
**Clinical Pearl / High-Yield Fact**
The sandfly vector for Kala-azar is typically found in rural areas with poor sanitation and hygiene, where the parasite is more likely to be transmitted to humans. Awareness of the vector's habitat and behavior is crucial for implementing effective control measures.
**Correct Answer:** D. *Phlebotomus*