<prompt> In a 3 year old child, most common cause of hepatitis B is -Pin prickSaliva exchangePerinatalBlood transfusion  <response>: Ans. is d i.e., Blood transfusion Children usually acquire infection indirectly, through parenteral route from hepatitis B contaminated blood transfusion. Other modes of transmission in children : - i Sharing of contaminated hypodermic needles used for multiple doses of infection. ii Shaving razors. iii Sexual contact Adolescent boy girls. 