title: Haemophilus influenzae serotype a as a cause of serious invasive infections.
abstract: Haemophilus influenzae, particularly H influenzae serotype b (Hib), is an important pathogen that causes serious diseases like meningitis and septicaemia. Since the introduction of Hib conjugate vaccines in the 1990s, the epidemiology of invasive H influenzae disease has changed substantially, with most infections now caused by non-Hib strains. We discuss the importance of H influenzae serotype a (Hia) as a cause of serious morbidity and mortality and its global epidemiology, clinical presentation, microbiology, immunology, prevention, and control. Much like Hib, the capsule of Hia is an important virulence factor contributing to the development of invasive disease. Molecular typing of Hia has identified distinct clonal groups, with some linked to severe disease and high case-fatality rates. Similarities between Hia and Hib capsules, their clinical presentation, and immunology of infection suggest that a bivalent Hia-Hib capsular polysaccharide-protein conjugate vaccine could offer protection against these two important serotypes of H influenzae.
authors.affiliation: Northern Ontario School of Medicine, Lakehead University, Thunder Bay, ON, Canada.
authors.forename: Marina
authors.initials: M
authors.lastname: Ulanova
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada. Electronic address: raymond.tsang@phac-aspc.gc.ca.
authors.forename: Raymond S W
authors.initials: RSW
authors.lastname: Tsang
mesh_terms: D016667:Bacterial Capsules / Q000378:metabolism; D014943:Global Health; D006192:Haemophilus Infections / Q000453:epidemiology / Q000382:microbiology* / Q000401:mortality / Q000473:pathology*; D018073:Haemophilus Vaccines / Q000008:administration & dosage / Q000276:immunology; D006193:Haemophilus influenzae / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity*; D006801:Humans; D017720:Molecular Epidemiology; D058889:Molecular Typing; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D018073:Haemophilus Vaccines; D037521:Virulence Factors