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Objectives: This report aims to use tetanus hospitalization data to describe the epidemiology in Canada from 1995 to 2019 and to assess progress on national reduction targets, including validating that Canada has eliminated maternal and neonatal tetanus (MNT)., Methods: Tetanus hospitalizations and fatalities occurring between 1995 and 2019 were retrieved from the Canadian Institute for Health Information (CIHI) and Statistics Canada. Cases coded with ICD-10 codes A33, A34, or A35 as the primary diagnosis (or ICD-9 equivalents) were included. The Canadian national case definition was used for generic tetanus and definitions from the World Health Organization were referenced for MNT. R version 4.0.2 was used for analyses., Results: From 1995 to 2019, 155 non-MNT, 6 neonatal, and 0 maternal tetanus cases were retrieved from CIHI. However, all 6 neonatal cases were excluded after validating with provincial/territorial public health officials. In the same time period, there were 91 national notifications of tetanus. Cases were distributed relatively equally across the country, with the exception of the territories, where zero cases were reported. Adults 75 and over had significantly higher incidence rates compared to younger age groups (p<0.001). Ten deaths were reported during the timeframe., Conclusion: Tetanus incidence remains low and hospitalization data reveal that Canada has met its reduction target of maintaining 5 cases or fewer annually in recent years. For MNT, Canada has successfully met the elimination target of zero cases. Continued vaccination efforts must be practiced for all age groups, including those aged 75 years and older, to sustain targets moving forward., (© 2023. Crown.)

Background: Pertussis, also known as whooping cough, is an endemic vaccine-preventable disease that affects the respiratory tract and is caused by the bacterium Bordetella pertussis . Between 1999 and 2004, the adolescent booster dose of pertussis was introduced across Canada. This report describes the epidemiology of pertussis in Canada from 2005 to 2019, the period after adolescent acellular vaccination was recommended., Methods: We analyzed pertussis incidence by year, age groups, sex and geographic region using national surveillance data from the Canadian Notifiable Disease Surveillance System. Hospitalization data from the Discharge Abstract Database was used to investigate pertussis hospitalizations by sex and age. Deaths from pertussis were explored using Statistics Canada's vital statistics data. Vaccination coverage data was gathered from the 2019 Childhood National Immunization Coverage Survey and 2018-2019 Seasonal Influenza Vaccination Coverage Survey., Results: Between 2005 and 2019, there were a total of 33,481 pertussis cases with the average annual incidence rate of 6.4 cases per 100,000 population. The highest average age-specific incidence rate was among infants under one year of age (n=68.7 cases per 100,000 population). There were a total of 1,593 pertussis hospitalizations; nearly 80% of these hospitalizations were infants under one year of age. Hospitalization rates were 8.2 times higher in infants three months or younger compared to infants four to 11 months of age. There were 17 deaths; all among infants under one year of age., Conclusion: The highest morbidity and fatality of pertussis were among infants under one year of age. It is important to take measures to reduce transmission to infants who are too young to be vaccinated. Increasing vaccine coverage in children and pregnant women are important to reduce the burden of disease., Competing Interests: Competing interests: None.

Background: A variety of routine childhood and adolescent meningococcal vaccination programs using monovalent (serogroup C) and quadrivalent (A, C, Y, W) conjugate vaccines have been implemented in Canada since 2002, resulting in a decrease in invasive meningococcal disease (IMD) incidence, particularly in serogroup C. Meningococcal vaccines have also been used for outbreak response, including the multicomponent vaccine serogroup B vaccine. This report describes the epidemiology of IMD in Canada from 2012 to 2019., Methods: Case data were obtained from the National Enhanced IMD Surveillance System between January 1, 2012 and December 31, 2019. Isolates were sent to the National Microbiology Laboratory for confirmation of serogroup and further studies including phenotype and clonal complex identification., Results: A total of 983 cases of IMD were reported between 2012 and 2019. Overall, the age-adjusted incidence of IMD from 2012 to 2019 was 0.34 cases per 100,000 population per year when standardized to the Canadian 2011 population age distribution (95% CI: 0.32-0.36). Infants younger than one year of age had the highest average age-specific incidence rate (3.6 cases per 100,000 population per year, 95% CI: 2.8-4.3). The highest age-adjusted incidence rate was associated with serogroup B (0.17 cases per 100, 000 population per year, 95% CI: 0.16-0.19). Prior to 2015, most invasive serogroup W isolates were identified as clonal complex 22 (ST-22 CC) and the increase in serogroup W in Canada in recent years has been associated with the replacement of the endemic ST-22 CC with the hyper-virulent ST-11 CC., Conclusion: Invasive meningococcal disease is a rare but severe infection in Canada that mostly affects the very young. Serogroup B continues to account for the greatest proportion of disease. Serogroup W associated with ST-11 CC is becoming a growing contributor of disease in all age groups not protected by serogroup W-containing vaccines., Competing Interests: Competing interests: None., (Public Health Agency of Canada, 2022.)

Background: The International Circumpolar Surveillance (ICS) program conducts surveillance on five invasive bacterial diseases: pneumococcal disease (IPD), group A streptococcus (iGAS), Haemophilus influenzae (Hi), meningococcal disease (IMD) and group B streptococcus (GBS). Invasive bacterial diseases have a higher burden of disease in northern populations than the rest of Canada., Methods: To describe the epidemiology of invasive bacterial diseases in northern Canada from 1999 to 2018, data for IPD, iGAS, Hi, IMD and GBS were extracted from the ICS program and the Canadian Notifiable Diseases Surveillance System (CNDSS) and analyzed., Results: The annualized incidence rates for IPD, iGAS, Hi, GBS and IMD were 23.3, 10.5, 8.9, 1.9 and 1.1 per 100,000 population, respectively. The incidence of IPD, iGAS and Hi serotype b were 2.8, 3.2 and 8.8 times higher, respectively, in northern Canada than in the rest of Canada. Rates of disease decreased statistically significantly for IPD (β=-0.02) and increased statistically for iGAS (β=0.08) and Hi serotype a (β=0.04) during the study period. In Northern Canada, the annualized incidence rates for IPD, iGAS and Hi were statistically higher for Indigenous residents than for non-Indigenous residents. The highest incidence rates were among the very young and older age groups., Conclusion: Invasive bacterial diseases represent a high burden of disease in Canada's northern populations. Indigenous peoples, children and seniors are particularly at risk., Competing Interests: Competing interests: None.

This article provides a summary of the epidemiology of multisystem inflammatory syndrome in children (MIS-C) cases reported nationally in Canada by provincial and territorial health authorities. Multisystem inflammatory syndrome in children is a post-viral inflammatory syndrome that temporally follows coronavirus disease 2019 (COVID-19). Symptoms may include fever, abdominal pain, vomiting, diarrhea, skin rash and other signs of inflammation. In Canada, MIS-C is rare, with 269 cases reported to the Public Health Agency of Canada between March 11, 2020 and October 2, 2021. One hundred forty-two (53%) of these cases were lab-confirmed COVID-19 cases or epidemiologically-linked with COVID-19 cases. Cases have been reported in infants as young as one week to youth as old as 18 years, with a median age of six years. Cases were more likely to occur in males than females (58% vs 42%, respectively; p =0.006). Almost all MIS-C cases (99%) required hospitalization and 36% required intensive care unit admission. No deaths have been reported to date. The time trend of MIS-C aligns with the incidence rate time trend of COVID-19 reported in children, with a two to six-week lag., Competing Interests: Competing interests: None.

Competing Interests: Competing interests: None.

Background: Canada has maintained a low incidence of toxigenic diphtheria since the 1990s, supported by continued commitment to publicly funded vaccination programs., Objective: To determine whether hospitalization data, complemented with notifiable disease data, can describe the toxigenic respiratory and cutaneous diphtheria burden in Canada, and to assess if Canada is meeting its diphtheria vaccine-preventable disease-reduction target of zero annual cases of locally transmitted respiratory diphtheria., Methods: Diphtheria-related hospital discharge data from 2006 to 2017 were extracted from the Discharge Abstract Database (DAD), and diphtheria case counts for the same period were retrieved from the Canadian Notifiable Disease Surveillance System (CNDSS), for descriptive analyses. As data from the province of Québec are not included in the DAD, CNDSS cases from Québec were excluded., Results: A total of 233 diphtheria-related hospitalizations were recorded in the DAD. Of these, diphtheria was the most responsible diagnosis in 23. Half the patients were male (52%), and 57% were 60 years and older. Central region (Ontario) accounted for the most discharge records (61%), followed by Prairie region (Alberta, Manitoba and Saskatchewan; 23%). Cutaneous diphtheria accounted for 43% of records, and respiratory diphtheria accounted for 3%, with the remainder being other diphtheria complications or site unspecified. Two records with diphtheria as the most responsible diagnosis resulted in inpatient deaths. Eighteen cases of diphtheria were reported through CNDSS. Cases occurred in all age groups, with the largest proportions among those aged 20 to 59 years (39%) and those aged 19 years and younger (33%). Cases were only reported in the Prairie (89%) and West Coast (British Columbia; 11%) regions., Conclusion: Hospital administrative data are consistent with the low incidence of diphtheria reported in CNDSS, and a low burden of respiratory diphtheria in Canada. Although Canada appears to be on track to meet its disease-reduction target, information on endemic transmission is not available., Competing Interests: Competing interests: None.

Background: The Public Health Agency of Canada (PHAC) has conducted enhanced measles surveillance since 1998, the year endemic measles transmission was eliminated in Canada. The objective of this annual national measles surveillance report is to provide an epidemiologic summary of measles activity reported in Canada for 2019 in order to provide evidence to support the continued verification of Canada's measles elimination status., Methods: Measles surveillance data are housed in the Canadian Measles and Rubella Surveillance System (CMRSS) database. Descriptive analyses of demographics and risk factors were performed. Outbreak characteristics were summarized and genotypic analyses conducted. Surveillance, laboratory and vaccine coverage data for 2019 were used to assess Canada's status against the Pan American Health Organization (PAHO) essential criteria for the verification of measles elimination., Results: In 2019, 113 measles cases were reported in Canada (crude incidence rate of 3.0 cases per 1,000,000 population). Of these cases, 42 (37%) were imported into Canada, and of the imported cases, 12 (29%) resulted in further transmission. Infants younger than one year had the highest age-specific incidence rate at 13.1 cases per 1,000,000 population. Only 29% of cases had one or more documented doses of measles-containing vaccine. One-fifth (19%) of cases were hospitalized; no deaths were reported. Genotype information was available for 100% of outbreaks reported in 2019 and 90% of non-outbreak-related measles cases; of cases with genotype information available, 27% were B3 and 73% were D8., Conclusion: Despite meeting/partially meeting only three out of four of PAHO's essential criteria for measles elimination status, there is no evidence that endemic measles transmission has been reestablished in Canada., Competing Interests: Competing interests: None.

Background: An increase in mumps incidence was observed in late 2016 (365 cases in 2016 compared to 59 cases in 2015). This unusual level of mumps activity prompted the Public Health Network Council and the National Advisory Committee on Immunization to request situation awareness updates from the Centre for Immunization and Respiratory Infectious Diseases (CIRID) at the Public Health Agency of Canada in 2017 and 2018., Methods: A mumps outbreak survey was developed and administered by epidemiologists within CIRID and sent electronically to provincial and territorial public health officials in charge of mumps surveillance. The survey collected information on mumps outbreaks pertaining to demographics, risk factors, laboratory data and public health interventions. The first survey collected data on outbreaks occurring between January 1, 2016 and February 28, 2017, while the second survey contained outbreak data from January 1, 2017 to July 31, 2018. Duplicate outbreaks entries were removed., Results: The response rate for the first and second surveys was 61% and 69%, respectively. Twenty-four mumps outbreaks across nine provinces were reported between January 1, 2016 and July 31, 2018, for a cumulative total of 881 mumps cases. Adolescents and adults 15 to 39 years of age accounted for the majority of cases (80.6%). Specifically, adults 20 to 24 years of age represented the largest proportion of cases (24.6%). Community and social gatherings were the most common exposure setting (62.5%). Slightly more than one third of cases were known to have received at least two doses of mumps-containing vaccine (35.6%)., Conclusion: Results from the surveys indicate that the increase in mumps activity was widespread throughout Canada, affecting multiple jurisdictions. Young adults accounted for the largest proportion of cases. These surveys provided evidence to support recommendations on the use of additional mumps vaccination in outbreak settings., Competing Interests: Competing interests: No potential competing interests were disclosed.

Starting in 2014, biennial clusters of acute flaccid myelitis (AFM), frequently described as "polio-like" illness, have been reported across the United States and elsewhere, often linked to enteroviruses. To assess AFM trends in Canada, we reviewed the Canadian Acute Flaccid Paralysis Surveillance System (CAFPSS) for cases reported during the 2018 and 2019 calendar years that meet the Centers for Disease Control and Prevention case definitions for AFM. A total of 10 cases (8 in 2018 and 2 in 2019) met the confirmed AFM case definition and 30 (26 in 2018 and 4 in 2019) met the probable AFM case definition. Sixty percent of confirmed and probable cases were younger than five years old, and all cases had symptom onset between the months of July and October. Enteroviruses were detected in 50% of confirmed cases. At the time of writing this report, 2020 AFM data were not yet available; it is unknown if a spike in AFM cases will be seen in 2020., Competing Interests: Competing interests: None.

Objective: The acellular pertussis vaccine was introduced into the routine childhood immunization schedule across Canada in 1997-98 and adolescent booster doses were added between 1999 and 2005. We sought to assess the impact of these changes on infant pertussis hospitalizations and admissions to intensive care units (ICU) in Canada., Methods: Hospitalizations with a primary diagnosis of pertussis were extracted from the Canadian Discharge Abstract Database (DAD) for cases with hospital discharge dates between 1981 and 2016 using relevant ICD-9 and ICD-10 codes. Only cases with age less than one year at time of admission were included. Disease severity was assessed by admission to ICU. Cases were categorized into two periods: pre-program implementation period (1981-1995) and the post-program implementation period (2006-2016). Incidence rates, risk ratios, and rate differences were calculated for each period and comparisons for the two periods were done using chi-squared and t-tests. Quasi Poisson analysis was used to investigate trends., Results: When comparing the pre- and post-implementation periods, the average annual hospitalization rates for infants less than 1 year declined from 165.1 (95% CI 161.3, 168.9) to 33.6 (95% CI 31.6, 35.6) pertussis-related admissions per 100,000 population, with a corresponding reduction in the risk ratio of 4.9 (95% CI 4.6, 5.2). The risk of admission into an ICU was 1.58 times higher in the pre- versus post-implementation period while the highest reduction in average annual hospitalizations was 263.3 admissions per 100,000 population in infants 2 months of age. In the post-implementation period, infants less than 1 month of age had the highest average annual hospitalization rate at 126.6 (95% CI 113.1, 140.1) hospitalizations per 100,000 infants., Conclusion: Infant pertussis hospitalizations have reduced greatly over time. Infants under 2 months of age remain the most at-risk age group for hospitalization and admission to ICU., (Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.)

With the rapid international spread of severe acute respiratory syndrome (SARS) from March through May 2003, Canada introduced various measures to screen airplane passengers at selected airports for symptoms and signs of SARS. The World Health Organization requested that all affected areas screen departing passengers for SARS symptoms. In spite of intensive screening, no SARS cases were detected. SARS has an extremely low prevalence, and the positive predictive value of screening is essentially zero. Canadian screening results raise questions about the effectiveness of available screening measures for SARS at international borders.

With the recent introduction of polysaccharide-protein conjugated vaccines for the control of serogroup C meningococcal disease and the emergence of different variants of serogroup C meningococci, it is likely the epidemiology of meningococcal disease in many countries may be affected. We have therefore analysed and reported the characteristics of Neisseria meningitidis strains collected in 2001 from the Canadian surveillance program on invasive meningococcal disease. Only strains collected from normally sterile clinical sites of patients were studied. Of the 289 isolates obtained from individual patients, 173 (59.9%) were serogroup C, 76 (26.3%) were serogroup B, 30 (10.4%) were serogroup Y, and 10 (3.5%) were serogroup W135. Ninety-six percent of the serogroup C isolates belonged to the ET-15 clone, with an additional 2.3% belonging to other electrophoretic types within the ET-37 clonal complex. Different antigenic variants of the endemic serogroup C ET-15 clone were responsible for localized outbreaks in different parts of the country. One novel variant with the antigenic composition of C:2a:P1.1,7 was reported in two provinces, Quebec and Ontario. Eighteen percent of the meningococci isolated from patients in Ontario belonged to serogroup Y, compared with only 8% in the rest of Canada. The current data highlight the importance of strain characterization by serogroup, serotype, and serosubtype antigens in providing useful information for the surveillance of meningococcal disease in Canada.

The relative frequency of serogroups of Neisseria meningitidis associated with meningococcal disease in Canada during the period January 1, 1999 to June 30, 2001 was examined. Of the 552 strains of N meningitidis collected from clinical specimens of normally sterile sites, 191 (34.6%), 276 (50.0%), 61 (11.1%) and 23 (4.2%) were identified by serological and molecular methods as serogroups B, C, Y and W135, respectively. About half (50.8%) of the serogroup Y isolates were isolated in the province of Ontario. The two most common serotypes found were 2c and 14. Most of the serogroup Y strains isolated from patients in Ontario were serotype 2c, while serotype 14 was the most common serotype associated with disease in the province of Quebec. The two most common serosubtypes found among the serogroup Y meningococci were P1.5 and P1.2,5. Laboratory findings, based on antigenic analysis, did not suggest that these serogroup Y strains arise by capsule switching from serogroups B and C strains. This study documented a higher incidence of finding serogroup Y meningococci in clinical specimens from patients in Ontario compared to the rest of Canada, and parallels the increase in serogroup Y meningococcal disease reported in some parts of the United States.

Background: There are limited clinical and epidemiological data on patients diagnosed with Bell's palsy. While investigating an apparent clustering of Bell's palsy, we sought to characterize the spectrum of illness in patients with this diagnosis., Methods: A telephone survey of persons with idiopathic facial (Bell's) palsy in the Greater Toronto Area (GTA, population = 4.99 million) and Nova Scotia (population = 0.93 million) from August 1 to November 15, 1997 collected information on subject demographics, neurological symptoms, constitutional symptoms, medical investigation and management. Information regarding potential risks for exposure to infectious agents, past medical history, and family history of Bell's palsy was also collected. Subjects with other secondary causes of facial palsy were excluded., Results: In the GTA and Nova Scotia, 222 and 36 patients were diagnosed with idiopathic facial (Bell's) palsy, respectively. The crude annualized incidence of Bell's palsy was 15.2 and 13.1 per 100,000 population in the GTA and Nova Scotia, respectively. There was no temporal or geographical clustering, and symptomatology did not differ significantly between the two samples. The mean age was 45 years, with 55% of subjects being female. The most common symptoms accompanying Bell's palsy were increased tearing (63%), pain in or around the ear (63%), and taste abnormalities (52%). A significant number of patients reported neurological symptoms not attributable to the facial nerve., Conclusion: No clustering of cases of Bell's palsy was observed to support an infectious etiology for the condition. Misdiagnosis of the etiology of facial weakness is common. Patients diagnosed with Bell's palsy have a variety of neurological symptoms, many of which cannot be attributed to a facial nerve disorder., (Copyright 2002 S. Karger AG, Basel)

Parents of children who received blood or blood products between 1984 and 1990 were notified about the potential risk of hepatitis C virus (HCV) infection. Data were collected about knowledge, attitudes and intended behaviours to determine the acceptability of the notification process. Demographic variables that may predict responses to notification were also recorded and analysed. Recipients were sent couriered letters explaining HCV risk, and the survey questionnaire. Sera were screened for HCV antibody and reactive samples confirmed with a recombinant immunoblot assay (RIBA). Four letter recipients were RIBA positive for a prevalence of 1.1% (4/358) in the notification group. Thirty-two percent of respondents did not know their child had been transfused and 58% did not know about the potential risk of HCV infection. Although 90% (165/185) felt the notification was valuable, 65% reported emotional distress (fear, worry, anger, very depressed). Responders were similar to non-responders except for HCV testing rate (76.2% v. 59.8%, p < 0.0002). Parents of children at risk of transfusion-acquired HCV virus approved of notification programs, but experienced some emotional distress. Awareness of transfusion history or risk of HCV was not universal, indicating the need to address notification to individuals, rather than through public education campaigns alone.

The 2000-2001 season was a relatively mild season worldwide. In Canada, lower than usual activity was reported for all national indicators of influenza activity, including the rate of influenza-like illness (ILI), the percentage of laboratory-confirmed cases of influenza and provincial/territorial influenza activity levels. However, there were a number of interesting characteristics of this year's influenza season. In contrast to the predominance of influenza A, and in particular the A/Sydney/5/97 (H3N2)-like virus over the past 3 years, influenza B predominated overall this season. Influenza A (H3N2) accounted for < 1% of all characterized isolates (H1N1 accounted for 49% of isolates). Increased laboratory-confirmed influenza activity began in the West (Yukon, prairie provinces and British Columbia) in mid-December, followed by the Atlantic provinces in mid- to late January and Ontario and Quebec in mid- February and March.

Objectives: To determine if a heightened, passive surveillance system increases the number of physicians reporting two notifiable diseases during a six-month period., Methods: We conducted a randomized trail among 145 community-based primary care physicians in two counties in Eastern Ontario. Intervention group physicians received a three-part intervention aimed at improving their communication with the health unit to whom all physicians are mandated to report notifiable diseases. The control group physicians remained part of the usual disease reporting system. The outcome was assessed by a relative risk comparing the number of physicians reporting among the intervention group to that in the control group., Results: Seventy physicians received the intervention and 75 physicians were in the control group. The relative risk for the number of physicians reporting at least one case was 5.9 (95% CI 2.6-13.2)., Conclusions: The intervention had an impact on reporting of notifiable diseases by physicians.