The small Gram negative rod-shaped bacterium Haemophilus influenzae capsular “type b” (Hib) is a relevant cause of serious invasive diseases (bacteraemia, septicaemia, meningitis, septic arthritis, purulent pericarditis, and less frequently endocarditis, osteomyelitis, or peritonitis). Additional disease manifestations are epiglottitis and cellulitis. Non-invasive diseases include otitis media and community acquired pneumonia (CAP).
While there are 6 capsular types (a-f) and non-typeable strains (NTHi), capsular type b (“Hib”) caused the vast majority of invasiveH. influenzae infections by crossing the cells lining the respiratory tract into the bloodstream with subsequent spreading to other organs. NTHi usually cause only mucosal infections.
As the clinical manifestation mentioned above can be caused by many different microorganisms, diagnosing Hib diseases require puncture of the infected organ followed by classical microbiological culture techniques, antigen detection testing or polymerase chain reaction.
Because invasive Hib disease can progress rapidly, prompt and accurate diagnosis is important to ensure that appropriate antibiotics can be given in a timely fashion. When Hib disease goes untreated or treatment is delayed, this may result in severe consequences such as hearing loss, chronic seizure problems, learning disabilities and even death.
Safe and effective polysaccharide-conjugate vaccines to prevent Hib disease have been available for more than 20 years. Every infant should receive Hib vaccine either alone or in combination with other childhood vaccines.