(a) Describe the life cycle of HIV from the time of its entry into the human body till full blown AIDS sets in.

HIV enters human body and enter macrophage cells , where viral RNA is

introduced in the cell, Viral DNA is produced by reverse transcription, Viral

DNA incorporated in host genome, New viral RNA is produced by the infected cell, New viruses are produced, which enter T-helper cells replicate and produces its progeny, Progeny viruses attack other T helper cells, this is repeated leading to progressive decline in the number T helper cells, person become immunodeficient and HIV AIDS develop /

• Chills , and high fever occurs in a cyclic order/every $\displaystyle 2$-$\displaystyle 3$ days,

• fever is due to the toxic haemozoin,

• release at the time of RBC rupture.

Sexual cycle of the malarial parasite in the mosquito host: sexual stages (gametocytes) develop in red blood cells → female mosquito takes up gametocytes with the blood meal → fertilisation and development take place in the mosquito's intestine → mature infective stages (sporozoites) escape from the intestine and migrate to the mosquito salivary glands.