Haemophilus influenzae type b (Hib) is the most common community-acquired invasive bacterial infection of Australian children.

Infection usually presents as meningitis or epiglottitis but other manifestations include pneumonia, septic arthritis/osteomyelitis, cellulitis or sepsis without an identifiable focus.

Hib are part of the normal nose and throat flora and spread is thought to occur via respiratory secretions.

Hib can be found in up to 5% of normal pre-school children.

The rates may be even higher in young contacts of clinical cases. These contacts also have a several hundred fold increased risk of contracting invasive disease themselves.