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Tsang RSW, Shuel M, Ahmad T, Hayden K, Knox N, Van Domselaar G, Hoang L, Tyrrell GJ, Minion J, Van Caeseele P, Kus JV, Ulanova M, Lefebvre B, Haldane D, Garceau R, German G, Zahariadis G, Hanley B, Kandola K, Patterson M. Whole genome sequencing to study the phylogenetic structure of serotype a Haemophilus influenzae recovered from patients in Canada. Can J Microbiol 2019; 66:99-110. [PMID: 31661630 DOI: 10.1139/cjm-2019-0406] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study examined the phylogenetic structure of serotype a Haemophilus influenzae (Hia) isolates recovered from patients in Canada. Hia isolates from 490 separate patients and an American Type Culture Collection (ATCC) strain were analyzed by multilocus sequence typing (MLST), with 18 different sequence types (STs) identified. Most (85.7%) Hia patient isolates were typed as ST-23 and another 12.7% belonged to 14 different STs with 6, 5, or 4 MLST gene loci related to ST-23 (ST-23 complex). Core genome single-nucleotide variation phylogeny (SNVPhyl) on whole genome sequence (WGS) data of 121 Hia patient isolates representing all identified STs and the ATCC strain revealed 2 phylogenetic populations, with all the ST-23 complex isolates within 1 population. The other phylogenetic population contained only the ATCC strain and 3 patient isolates. Concatenated hitABC sequences retrieved from WGS data and analyzed by MEGA (Molecular Evolutionary Genetic Analysis) alignment confirmed the phylogeny obtained by SNVPhyl. The sodC gene was found only in isolates in the minor phylogenetic population. The 2 phylogenetic populations of the Canadian Hia isolates are similar to the 2 clonal divisions described for serotype b H. influenzae. Combining MLST, core SNVPhyl, and hitABC gene sequence alignment showed that most (99.4%) Canadian Hia patient isolates belonged to 1 major phylogenetic population.
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Affiliation(s)
- Raymond S W Tsang
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Michelle Shuel
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Tauqeer Ahmad
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Kristy Hayden
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Natalie Knox
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.,Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Gary Van Domselaar
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.,Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Linda Hoang
- BC Public Health Microbiology and Reference Laboratory, Vancouver, British Columbia, Canada
| | | | - Jessica Minion
- Roy Romanow Provincial Laboratory, Regina, Saskatchewan, Canada
| | | | - Julianne V Kus
- Public Health Ontario, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Marina Ulanova
- Northern Ontario School of Medicine, Thunder Bay, Ontario, Canada
| | - Brigitte Lefebvre
- Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Quebec, Canada
| | - David Haldane
- Nova Scotia Health Authority, Halifax, Nova Scotia, Canada.,Dalhousie University, Halifax, Nova Scotia, Canada
| | - Richard Garceau
- Communicable Disease Control Unit, Department of Health, Government of New Brunswick, Fredericton, New Brunswick, Canada
| | - Greg German
- Department of Health, Government of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
| | - George Zahariadis
- Provincial Public Health Laboratory, Eastern Health Microbiology Services, St. John's, Newfoundland and Labrador, Canada.,Department of Laboratory Medicine, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Brendan Hanley
- Department of Health and Social Services, Government of Yukon, Whitehorse, Yukon, Canada
| | - Kami Kandola
- Department of Health and Social Services, Government of Northwest Territories, Yellowknife, Northwest Territories, Canada
| | - Michael Patterson
- Department of Health, Government of Nunavut, Iqaluit, Nunavut, Canada
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Shoukat A, Van Exan R, Moghadas SM. Cost-effectiveness of a potential vaccine candidate for Haemophilus influenzae serotype 'a'. Vaccine 2018; 36:1681-1688. [PMID: 29459062 DOI: 10.1016/j.vaccine.2018.01.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 01/12/2018] [Accepted: 01/17/2018] [Indexed: 02/06/2023]
Abstract
The preceding decade has witnessed the emergence of severe community-acquired acute infections caused by Haemophilus influenzae serotype a (Hia), with alarming incidence rates in North America, particularly among indigenous populations. The remarkable success of Hib conjugate vaccine over the past 20 years signify the development of an Hia vaccine candidate as a prevention measure to reduce the incidence of invasive Hia disease. However, quantifications of the long-term epidemiologic and economic impacts of vaccination are needed to inform decision on investment in Hia vaccine development and immunization programs. We sought to evaluate the cost-effectiveness of an Hia vaccine with a similar routine infant immunization schedules currently in practice for Hib in Canada. We developed and parameterized an agent-based simulation model using age-specific incidence rates reported for Nunavut, a Canadian territory with predominantly aboriginal populations. Our results, based on statistical analyses of the incremental cost-effectiveness ratio, show that an Hia conjugate vaccine is highly cost-effective. Sustaining an immunization program with vaccine coverages of 77% for primary series and 93% for booster dose over a 10-year period reduces the incidence of invasive disease by 63.8% on average from 9.97 to 3.61 cases, per 100,000 population. The overall costs of disease management in year 10 are reduced by 53.4% from CDN $1.863 million (95% CI: $1.229-$2.519 M) to CDN $0.868 million (95% CI: $0.627-$1.120 M). The findings suggest an important role for a conjugate vaccine in managing Hia disease as a growing public health threat.
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Affiliation(s)
- Affan Shoukat
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario M3J 1P3, Canada.
| | - Robert Van Exan
- Immunization & Policy Translation, 16 Fire Route 105, Trent Lakes, Ontario K0M 1A0, Canada
| | - Seyed M Moghadas
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario M3J 1P3, Canada
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Eton V, Schroeter A, Kelly L, Kirlew M, Tsang RSW, Ulanova M. Epidemiology of invasive pneumococcal and Haemophilus influenzae diseases in Northwestern Ontario, Canada, 2010-2015. Int J Infect Dis 2017; 65:27-33. [PMID: 28951105 DOI: 10.1016/j.ijid.2017.09.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 09/10/2017] [Accepted: 09/15/2017] [Indexed: 10/18/2022] Open
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.
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Affiliation(s)
- Vic Eton
- Northern Ontario School of Medicine, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada.
| | - Annette Schroeter
- Sioux Lookout Meno Ya Win Health Centre, Sioux Lookout, Ontario, Canada
| | - Len Kelly
- Sioux Lookout Meno Ya Win Health Centre, Sioux Lookout, Ontario, Canada
| | - Michael Kirlew
- Sioux Lookout Meno Ya Win Health Centre, Sioux Lookout, Ontario, Canada; Northern Ontario School of Medicine, Sioux Lookout, Ontario, Canada
| | - Raymond S W Tsang
- Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Winnipeg, Manitoba, Canada
| | - Marina Ulanova
- Northern Ontario School of Medicine, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada; Lakehead University, Thunder Bay, Ontario, Canada
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Tsang RSW, Ulanova M. The changing epidemiology of invasive Haemophilus influenzae disease: Emergence and global presence of serotype a strains that may require a new vaccine for control. Vaccine 2017; 35:4270-4275. [PMID: 28666758 DOI: 10.1016/j.vaccine.2017.06.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/23/2017] [Accepted: 06/01/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND More than two decades after the implementation of the Hib conjugate vaccine in North America, Haemophilus influenzae serotype a (Hia) has emerged as a significant cause of invasive disease in Indigenous communities. However, little is known about the global presence of this pathogen. METHODS We interrogated the H. influenzae Multi-Locus Sequence Typing (MLST) website (https://pubmlst.org/hinfluenzae/) by selecting for serotype a records. We also updated our previous literature review on this subject matter. RESULTS Hia has been reported from at least 35 countries on six major continents. However, most Hia diseases were associated with Indigenous communities. Clonal analysis identified two clonal populations with one typified as ST-23 responsible for most invasive disease in North America and being the predominant clone described on the H. influenzae MLST website. Incidence of invasive Hia disease in Indigenous communities in North America are similar to the rates of Hib disease reported prior to the Hib conjugate vaccine era. Hia causes severe clinical diseases, such as meningitis, septicaemia, pneumonia, and septic arthritis with case-fatality rates between 5.6% and 33% depending on the age of the patient and the genetic makeup of the Hia strain. CONCLUSION Although invasive Hia disease can be found globally, the current epidemiological data suggest that this infection predominantly affects Indigenous communities in North America. The clinical disease of Hia and the clonal nature of the bacteria resemble that of Hib. The high incidence of invasive Hia disease in Indigenous communities, along with potential fatality and severe sequelae causing long-term disability in survivors, may support the development of a new Hia conjugate vaccine for protection against this infection similar in design to the one introduced in the 1990s to control invasive Hib disease.
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Affiliation(s)
- Raymond S W Tsang
- Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
| | - Marina Ulanova
- Northern Ontario School of Medicine, Lakehead University, Thunder Bay, Ontario, Canada
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