Vic Eton1, Annette Schroeter2, Len Kelly2, Michael Kirlew3, Raymond S W Tsang4, Marina Ulanova5. 1. Northern Ontario School of Medicine, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada. Electronic address: etonvict@gmail.com. 2. Sioux Lookout Meno Ya Win Health Centre, Sioux Lookout, Ontario, Canada. 3. Sioux Lookout Meno Ya Win Health Centre, Sioux Lookout, Ontario, Canada; Northern Ontario School of Medicine, Sioux Lookout, Ontario, Canada. 4. Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Winnipeg, Manitoba, Canada. 5. Northern Ontario School of Medicine, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada; Lakehead University, Thunder Bay, Ontario, Canada.
Abstract
INTRODUCTION: North American indigenous populations experience a high burden of invasive bacterial infections. Because Streptococcus pneumoniae and Haemophilus influenzae have multiple antigenic variants, the existing vaccines cannot prevent all cases. This study addresses the current epidemiology of invasive H. influenzae and pneumococcal disease (IPD) in a region of Northwestern Ontario, Canada with a relatively high (82%) indigenous population. METHODS: Data were retrieved from a retrospective chart review at a hospital servicing a population of 29000 (82% indigenous), during January 2010-July 2015. RESULTS: Ten cases of invasive H. influenzae disease and 37 cases of IPD were identified. The incidence of both in the study population (6.3 and 23.1/100000/year, respectively) exceeded national rates (1.6 and 9.0/100000/year). H. influenzae serotype a (Hia) was the most common (50%), followed by non-typeable H. influenzae (20%). In adults, 77% of IPD cases were caused by serotypes included in the 23-valent pneumococcal polysaccharide vaccine. All paediatric IPD cases were caused by serotypes not included in the 13-valent pneumococcal conjugate vaccine. The case-fatality rate was 10% for invasive H. influenzae and 2.7% for IPD. Most cases exhibited substantial co-morbidity. CONCLUSIONS: In Northwestern Ontario, the incidence of invasive Hia disease exceeds that of H. influenzae type b (Hib) in the pre-Hib vaccine era. This provides strong support for the development of a new Hia vaccine. Improved pneumococcal vaccination of high-risk adults in the region is warranted.
INTRODUCTION: North American indigenous populations experience a high burden of invasive bacterial infections. Because Streptococcus pneumoniae and Haemophilus influenzae have multiple antigenic variants, the existing vaccines cannot prevent all cases. This study addresses the current epidemiology of invasive H. influenzae and pneumococcal disease (IPD) in a region of Northwestern Ontario, Canada with a relatively high (82%) indigenous population. METHODS: Data were retrieved from a retrospective chart review at a hospital servicing a population of 29000 (82% indigenous), during January 2010-July 2015. RESULTS: Ten cases of invasive H. influenzae disease and 37 cases of IPD were identified. The incidence of both in the study population (6.3 and 23.1/100000/year, respectively) exceeded national rates (1.6 and 9.0/100000/year). H. influenzae serotype a (Hia) was the most common (50%), followed by non-typeable H. influenzae (20%). In adults, 77% of IPD cases were caused by serotypes included in the 23-valent pneumococcal polysaccharide vaccine. All paediatric IPD cases were caused by serotypes not included in the 13-valent pneumococcal conjugate vaccine. The case-fatality rate was 10% for invasive H. influenzae and 2.7% for IPD. Most cases exhibited substantial co-morbidity. CONCLUSIONS: In Northwestern Ontario, the incidence of invasive Hia disease exceeds that of H. influenzae type b (Hib) in the pre-Hib vaccine era. This provides strong support for the development of a new Hia vaccine. Improved pneumococcal vaccination of high-risk adults in the region is warranted.
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