PLoS ONE (Jan 2015)

The Epidemiology of Invasive Haemophilus influenzae Non-Serotype B Disease in Ontario, Canada from 2004 to 2013.

  • Shalini Desai,
  • Frances B Jamieson,
  • Samir N Patel,
  • Chi Yon Seo,
  • Vica Dang,
  • Jill Fediurek,
  • Debeka Navaranjan,
  • Shelley L Deeks

DOI
https://doi.org/10.1371/journal.pone.0142179
Journal volume & issue
Vol. 10, no. 11
p. e0142179

Abstract

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Since the widespread use of Haemophilus influenzae (Hi) type b (Hib) vaccines among children aged <5 years, an increase in invasive non-Hib disease incidence has been reported internationally. We sought to describe the epidemiology of invasive non-Hib disease in Ontario, Canada (population ~13.5 million).Confirmed invasive non-Hib cases (non-typeable [NTHi] and serotypes a, c, d, e, and f) were obtained from the provincial laboratory data system from 2004-2013. Data were deterministically linked to the provincial reportable disease system to provide further case information. Antibiotic resistance data were analysed separately from 2010-2014. Descriptive analyses included incidence rates, age group, serotype, site of specimen collection and resistance patterns; ethnicity data were not available. Temporal trends were evaluated by Poisson regression and p-values <0.05 were considered significant.A total of 1307 cases of invasive non-Hib disease were included, increasing from 0.67 cases to 1.60 cases /100,000 from 2004 to 2013. Significant increases in the incidence of NTHi (0.50 to 1.28 cases/100 000 population), Hia (0.02 to 0.08 cases/100, 000) and Hif (0.13 to 0.18 cases/100, 000 population) were seen. Among persons aged 40-64 years, 3 Hi strains significantly increased over time; NTHi (0.22 to 0.99 cases/100, 000), Hia (0.00 to 0.06 cases/100, 000) and Hif (0.05 to 0.21 cases/100, 000). Among persons aged 65-84 years, there was a significant increase of NTHi (1.62 to 3.14 cases/100, 000) and Hia (0.00 to 0.34 cases/100, 000). Among persons aged 85+ years, only NTHi significantly increased from 4.89 to 10.28 cases/100, 000). Antimicrobial resistance (AMR) to ampicillin and clarithromycin was seen in greater than 25% of isolates but AMR did not increase over the duration of this study.The incidence of invasive non-Hib disease has increased over time; NTHi, Hif and Hia are emerging pathogens, and should be monitored.