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

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

doi:10.1371/journal.pone.0142179

Shalini Desai, Chi Yon Seo + Show 7 more

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https://doi.org/10.1371/journal.pone.0142179

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Abstract

BackgroundSince 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).MethodsConfirmed 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.ResultsA 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.ConclusionsThe incidence of invasive non-Hib disease has increased over time; NTHi, Hif and Hia are emerging pathogens, and should be monitored.

Highlights

Haemophilus influenzae (Hi) is a Gram negative facultative anaerobic coccobacillus
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)
The incidence of invasive non-Hib disease has increased over time; NTHi, Hif and Hia are emerging pathogens, and should be monitored

Summary

Introduction

Haemophilus influenzae (Hi) is a Gram negative facultative anaerobic coccobacillus. Strains may be unencapsulated (non-typeable or NTHi) or have a polysaccharide capsule (serotype af). Since the introduction of Hib vaccine for children under the age of 5 years, there has been a precipitous decline in the incidence of Hib disease both in Canada[4] and in other countries with Hib immunization programs[5,6]. These trends are similar for the province of Ontario, Canada (population 13.5 million in 2014)[7]. Since the widespread use of Haemophilus influenzae (Hi) type b (Hib) vaccines among children aged

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