$(a)$ Write the principles of treatment that are generally followed by a doctor to treat infectious diseases.
$(b)$ Write two ways by which $HIV$ ($AIDS$ virus) may get transmitted from one person to the other.

(N/A) Principles of treatment:
$(i)$ To reduce the effect of the disease: This involves symptomatic treatment,such as taking medicines to lower fever,reduce pain,or control loose motions.
$(ii)$ To kill the cause of the disease: This involves administering specific medicines (like antibiotics or antivirals) to kill the specific microbe responsible for the infection.
$(b)$ Two ways by which $HIV$ ($AIDS$ virus) is transmitted:
$(i)$ Through unprotected sexual contact with an infected person.
$(ii)$ Through the exchange of infected blood or blood products (e.g.,sharing needles or blood transfusion).