Previously called Pfeiffer’s bacillus after Richard Pfeiffer (1858-1945) who first described in 1892, it is a species of rod-shaped, gram-negative bacteria that is the major cause of bacterial meningitis and acute epiglottitis, as well as pneumonia, in young children (with more than 90% of all Hib infections occurring in children of 5 years of age or less). Occasionally, it leads to obstructive laryngitis, cellulitis, osteomyelitis and joint infections. Invasive Hib rates have fallen dramatically since the introduction of Hib vaccines, which are usually given at 2, 4 and 6 months, with a final booster at 12 to 15 months. Prior the Hib vaccine, about 20,000 cases of Hib in preschool children were reported in the US every year, compared to less than 300 cases after it was introduced.
See Meningitis