title: Population-based study of non-typable Haemophilus influenzae invasive disease in children and neonates.
abstract: The extent of non-capsulate, non-serotypable Haemophilus influenzae (NST) as a cause of serious invasive disease in children has not been fully defined. We describe the epidemiology of these childhood infections from cases identified during a continuing prospective survey of invasive H influenzae disease in the Oxford region, UK. 408 strains of H influenzae were isolated from cases of invasive disease. 383 (94%) were H influenzae type b (Hib), 24 (6%) were NST strains, and 1 was a type f strain. 3 of the NST strains were non-capsulate type b mutants (b-), but the remaining 21 strains were from the phylogenetically distinct and heterogeneous population of non-capsulate H influenzae (NC). 10 of the NC strains were isolated from neonates with sepsis; crude mortality rate was 40%, with an incidence of 4.6 cases per 100,000 livebirths. 11 NC strains were isolated from children after the neonatal period and under 10 years of age, 4 (36%) of which had severe, unrelated, predisposing conditions. The incidence of NC invasive diseases in these children was 0.5 per 100,000 per year. The attributable mortality for these infections was 10%. Infections due to these H influenzae strains are, after the implementation of Hib vaccines, likely to persist and represent a substantial proportion of the serious infections caused by this species.
authors.affiliation: Public Health Laboratory, John Radcliffe Hospital, Headington, Oxford, UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Falla
authors.forename: S R
authors.initials: SR
authors.lastname: Dobson
authors.forename: D W
authors.initials: DW
authors.lastname: Crook
authors.forename: W A
authors.initials: WA
authors.lastname: Kraak
authors.forename: W W
authors.initials: WW
authors.lastname: Nichols
authors.forename: E C
authors.initials: EC
authors.lastname: Anderson
authors.forename: J Z
authors.initials: JZ
authors.lastname: Jordens
authors.forename: M P
authors.initials: MP
authors.lastname: Slack
authors.forename: D
authors.initials: D
authors.lastname: Mayon-White
authors.forename: E R
authors.initials: ER
authors.lastname: Moxon
mesh_terms: D015139:Blotting, Southern; D002648:Child; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000382:microbiology; D006193:Haemophilus influenzae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D011446:Prospective Studies; D012703:Serotyping