Animal Physiology

Step 1: Identify the Disease:
"Dum-dum fever" is another name for **Kala-azar** or **Visceral Leishmaniasis**.
Step 2: Identify the Pathogen:
This disease is caused by the protozoan parasite **\Leishmania donovani**, which is transmitted by the sandfly (\Phlebotomus).
Step 3: Analyze Other Options:
(A) \Trypanosoma gambiense: Causes African Sleeping Sickness.
(B) \Ancylostoma duodenale: Hookworm (Helminth).
(C) \Leishmania tropica: Causes Cutaneous Leishmaniasis (Oriental sore/Delhi boil).
Step 4: Final Answer:
Option (D) is correct.

The intermediate host is the host in which a parasite undergoes asexual reproduction or development. The definitive host is where sexual reproduction occurs. Primary host is another term for definitive host. Reservoir hosts maintain the parasite in nature. Hence, the intermediate host harbours the asexual stages.

Concept: A hyperparasite is a parasite whose host is another parasite.
Explanation: {Nosema notabilis} is a microsporidian that infects the sporozoites of {Sphaerospora polymorpha}, which is itself a parasite of fish. Thus, {N. notabilis} is the hyperparasite in this chain.