Haemophilus influenzae type b infection is one of the most common cause of invasive bacterial infection in < 5 yr old children. Mass vaccination against Hib led to virtual elimination of the disease from such countries like Finland, UK, USA etc (1,2). In developing countries like India, it is still a major cause of meningitis & pneumonitis as these countries can not afford mass vaccination programmes. There is an urgent need to establish the disease burden in such countries so that Govt. sponsored mass vaccination programmes can be started to decrease the disease burden due to Hib. This will help to eliminate or even eradicate Hib from world.

H. influenza organism :

Haemophilus species are commensals present in the upper respiratory tract of healthy humans. H.influenza is the most common amongst them. It is a gram -ve capsulated bacillus. The capsule is made up of repetitive units of poly ribosyl ribitol polysaccharide (PRP). Depending on the type of capsular PRP, H. influenza is further sub classified into types a to f. Of this, type b (Hib) is the most dreaded organism as it leads to invasive disease. 95% of invasive disease due to influenza occurs due to type b & 5% due to type a or other non-typable H. influenza organisms. 95% of Hib infection occur in children < 5yrs old. Non type b H. influenza usually causes upper respiratory infection & rarely invasive disease as reported from UK & India. (3)