Communicable disease factsheets

Haemophilus influenza type b (Hib)

Haemophilus influenza type b is a highly contagious bacterium which is known to cause meningitis, epiglottitis, pneumonia, septic arthritis, cellulitis, pericarditis, empyema and osteomyelitis. This fact sheet covers: the disease and its agent; spread of infection; prevention; surveillance and reporting.

The disease and its agent

Haemophilus influenza type b is a highly contagious bacterium which is known to cause meningitis, epiglottitis, pneumonia, septic arthritis, cellulitis, pericarditis, empyema and osteomyelitis. Before the introduction of Hib vaccines, this organism was the most frequent cause of life threatening infection in children under five years of age. About 60 per cent of all invasive Hib infection was manifested as meningitis, and most cases occurred in children under 18 months of age. Five per cent of cases were fatal and up to 15 per cent of survivors were left with neurological sequelae (eg. deafness, intellectual impairment). At least 500 cases of Hib occurred each year in children under 8 years of age and the annual mortality was around 10-15.

Spread of infection

Bacteria are spread in respiratory secretions by direct person-to-person contact during the infectious period. Hib is infectious as long as there are organisms present in the nose and throat and has an incubation period of around 2-4 days.

Prevention

Conjugate Hib vaccines consisting of purified polysaccharides (PRP) chemically linked (conjugated) to a carrier protein have been part of the Australian vaccination schedule since 1993. Since then there has been a decline of about 90 per cent in the incidence of invasive Hib diseases. Conjugated vaccines have been found to reduce oropharyngeal carriage of Hib in vaccinated children, thereby providing indirect protection for unimmunised children. The first dose of vaccine is normally given at 2 months of age.

Children with Hib infections should be excluded from child care/school until a course of appropriate antibiotic is completed and a medical practitioner has confirmed that the child may return.

Surveillance and reporting

Cases reported to the State and Territory health departments are collected through the National Notifiable Diseases Surveillance System, for national reporting through the Communicable Diseases Intelligence (CDI).