Model released. Hib immunisation. Child being immunised against a range of diseases caused by the Hib bacterium, Haemophilus influenzae type b. This is exclusively a human parasite and lives in the respiratory tract of healthy individuals. In young children, due to their immature immune system, it may cause dangerous diseases such as meningitis, epiglottis, septicaemia (blood poisoning), pneumonia, bone and joint infections. The Hib immunisation is considered to be safe and is usually given in three courses when the child is 2, 3 and 4 months old.