Haemophilus influenzae is a small Gram-negative coccobacillus colonizing the respiratory tract of humans. The bacterium may cause direct local infections like otitis media, as well as severe invasive diseases like meningitis.
In the pre-vaccine era, of the 6 capsular serotypes (a–f), type b caused the majority of invasive disease cases, whereas “nontypeable H. influenzae” (NTHi) and other capsular types predominate today.
H. influenzae infections affect mainly children <5 years as well as persons >60 years with underlying diseases like COPD.
Diagnosis of Hib disease is performed by classical microbiological culture techniques, antigen detection tests and polymerase chain reaction from blood samples, CSF or puncture samples.
If untreated or if treatment is delayed, invasive Hib diseases may result in severe consequences such as hearing loss, chronic seizures, learning disabilities, and even death.
Safe and effective polysaccharide-conjugate vaccines have been available for children for almost 30 years, reducing invasive Hib incidences from about 60 to <1 / 105. Today, largely DTP-based Hib-combinations are used.
After the primary series with 2 or 3 doses, depending on the product and local recommendations, a booster dose in the second year of life is needed to ensure long-term protection.
