Haemophilus influenzae type b (Hib) infections are a major cause of severe infections in children between 2 months and 5 years of age worldwide. It affects approximately 25000 patients each year. Severity of the symptoms of Hib infection depends on the patient's age, and infants between 4 months and 1 year of age are at highest risk for meningitis. Invasive disease due to Hib may produce various clinical syndromes including meningitis, arthritis, pneumonia, cellulitis, osteomyelitis, and epiglottitis. Mucosal infections, such as bronchitis, sinusitis and conjunctivitis, and otitis media, can also be caused by Hib, but they are considered to be noninvasive disease.
