Evaluation of Prenatal Hepatitis C Virus Prevalence Using Universal Screening, and Linkage to Care in a Real-World Setting in Ontario

OBJECTIVES

International infectious disease/obstetrical societies have recently recommended universal hepatitis C virus (HCV) prenatal screening and these same recommendations are forthcoming in Canada. At present, there is no formal analysis of universal HCV screening or linkage to care of pregnant people in Ontario. The objectives of our study were to determine the seroprevalence of HCV using 2 different methods to evaluate universal screening, as well as identify opportunities that may improve linkage to care.

METHODS

To assess seroprevalence in a large urban area, we aimed to test 12 000 de-identified samples submitted for prenatal HIV testing in the catchment area of Toronto Public Health for HCV antibodies. Then, to assess the seroprevalence as well as the operational impact and follow-up in a real-world setting, we completed a Quality Improvement Project (QIP) for 1 year at a large tertiary care obstetrical centre in London, Ontario.

RESULTS

From 2019 to 2021, 11 999 de-identified samples were screened from Toronto with a seroprevalence of 0.40 (95% CI 0.29-0.53). In London, 5771 people were screened in 2021 with a seroprevalence of 0.55% (95% CI 0.38-0.78). Taken together, those aged 26-35 years had the highest positivity; in the QIP, 9% had no documented risk factor, and 59% of individuals were not linked to the next step in HCV care.

CONCLUSIONS

HCV prenatal seroprevalence in Ontario is comparable to hepatitis B virus, and ∼15-30-fold higher than HIV. Diagnosis in pregnancy is critical to facilitate referrals for treatment between pregnancies and could increase screening among children born to positive women.

Antibiotic susceptibility of urine culture specimens in Ontario: a population-based cohort study

BACKGROUND

Surveillance of antimicrobial resistance is essential to mitigate its impact on population health and inform local empiric treatment practices. Our aims were to evaluate urine culture specimen susceptibility from a range of diverse settings and describe antibiotic susceptibility across all organisms and compare susceptibilities to that of Escherichia coli alone.

METHODS

In this descriptive cohort study, we measured the prevalence of organisms in urine culture specimens using linked province-wide administrative databases. Using positive urine cultures collected in Ontario between Jan. 1, 2016, and Dec. 31, 2017, we measured susceptibility to 6 classes of antibiotics using a weighted antibiogram for all organisms compared with E. coli alone.

RESULTS

We included 689 497 cultures derived from 569 399 patients and 879 778 test orders for specimens. For all organisms, the rates of susceptibility in the outpatient, inpatient and long-term care settings were 49.3%, 42.8% and 39.2%, respectively, for ampicillin; 83.1%, 72.7% and 69.7%, respectively, for nitrofurantoin; 80.3%, 64.8% and 73.1%, respectively, for trimethoprim-sulfamethoxazole; 87.2%, 74.1% and 66.2%, respectively, for ciprofloxacin; 90.6%, 73.6% and 85.1%, respectively, for aminoglycosides; and 82.6%, 57.5% and 73.5%, respectively, for cefazolin. We found resistance to 3 or more antibiotic classes in 20.6% of episodes for all organisms compared with 14.0% for E. coli alone. The average absolute difference in antibiotic susceptibility between all organisms and E. coli across all drugs was lowest in the outpatient setting (6.2%) and highest in the inpatient setting (14.6%).

INTERPRETATION

In this study, urinary organism prevalence and antimicrobial susceptibility varied across health care settings and patient populations, with implications for both antimicrobial resistance surveillance and clinical decision-making. Weighted antibiograms may be most useful for guiding empiric treatment of urinary infections in inpatient settings where the diversity of infectious organisms is higher than in the community.

Exploring the reasons for low pertussis vaccine effectiveness in Ontario, Canada, 2006-2008: a Canadian Immunization Research Network study

OBJECTIVES

Although pertussis vaccines have been widely used for many decades, a burden of illness persists. Resurgences in Ontario, Canada, have not been substantial in the past decade, but an outbreak of pertussis occurred in Toronto between 1 October 2005 and 31 March 2006. Previous Ontario studies found high vaccine effectiveness (VE) in the initial years post-immunization. In order to explore the impact of outbreaks and external factors on VE, we investigated pertussis VE during the period 2006-2008.

METHODS

We assessed pertussis VE using a frequency-matched case-control study for the period 1 March 2006 to 31 December 2008. We used logistic regression to estimate VE by age, time since last vaccination, and vaccination status according to the Ontario recommended schedule. We compared analyses including and excluding cases from Toronto, and to two recent Ontario pertussis VE studies.

RESULTS

We included 1797 confirmed cases and 7188 matched controls. Most cases were under 4 years of age during the study period. Pertussis VE was 3.8% (95% CI: - 21.0, 24.0) in the period 15-364 days following the last pertussis vaccine dose, and increased with increasing time since vaccination. Pertussis VE in the first 15-364 days excluding Toronto increased to 57.1% (95% CI: 26.0, 75.1), but the trend of increasing VE with time since vaccination persisted. Although VE was higher in older (6-11 years) than younger (0-5 years) children, it was lower at 12-13 years than after 14 years.

CONCLUSION

VE was lower in comparison with other studies conducted in Ontario, particularly in younger children. Various factors occurring during the study period may have influenced the results, including clinical testing of asymptomatic contacts, laboratory testing and methods and reporting practice, and a sensitive case definition. Further studies are needed to optimize methods for measuring VE to inform pertussis vaccine policy.

Patient and provider determinants of breast cancer screening among Ontario women aged 40-49: a population-based retrospective cohort study

PURPOSE

Canadian breast cancer screening guidelines state that mammography screening for women 40-49 should be individualized based on risk assessment and preferences. This retrospective cohort study describes the frequency of screening in women aged 40-49 and identifies patient and provider-level associations with screening.

METHODS

Administrative databases were linked. The overall cohort included Ontario women aged 40-49 between April 1, 2009 and March 31, 2019. Subgroups were created: the "screen" group included women who received a mammogram defined as screening (using a set of exclusion criteria) and the "routine screen" group included women with three or more screening mammograms. A multivariable multilevel logistic regression model accounting for patient and provider characteristics was fit to determine characteristics associated with routine screening. The intracluster correlation co-efficient was used to quantify the degree of variation across providers.

RESULTS

Of approximately 2 million eligible women, there were 532,596 (25.5%) in the screen group and 90,651 (4.3%) the routine screen group. There was an average of 0.30 and 0.52 screening mammograms per woman year, in the screen and routine screen groups, respectively. Routine screening was associated with periodic health exams (OR 1.21, 95% CI 1.20-1.22), receiving pap smears (OR 1.38, 95% CI 1.37-1.39), and fee-for-service models of care (OR 1.32, 95% CI 1.27-1.36). Over 20% of the variation in screening was due to systematic between-provider differences.

CONCLUSIONS

Approximately 4.3% of women aged 40-49 in Ontario received routine breast cancer screening with substantial variation across providers. Routine screening is associated with periodic health examinations, receipt of pap smears, and fee-for-service models of care.

The Benefits and Harms of Antibiotic Prophylaxis for Urinary Tract Infection in Older Adults

BACKGROUND

The role of antibiotics in preventing urinary tract infection (UTI) in older adults is unknown. We sought to quantify the benefits and risks of antibiotic prophylaxis among older adults.

METHODS

We conducted a matched cohort study comparing older adults (≥66 years) receiving antibiotic prophylaxis, defined as antibiotic treatment for ≥30 days starting within 30 days of a positive culture, with patients with positive urine cultures who received antibiotic treatment but did not receive prophylaxis. We matched each prophylaxis recipient to 10 nonrecipients based on organism, number of positive cultures, and propensity score. Outcomes included (1) emergency department (ED) visit or hospitalization for UTI, sepsis, or bloodstream infection within 1 year; (2) acquisition of antibiotic resistance in urinary tract pathogens; and (3) antibiotic-related complications.

RESULTS

Overall, 4.7% (151/3190) of UTI prophylaxis patients and 3.6% (n = 1092/30 542) of controls required an ED visit or hospitalization for UTI, sepsis, or bloodstream infection (hazard ratio [HR], 1.33; 95% confidence interval [CI], 1.12-1.57). Acquisition of antibiotic resistance to any urinary antibiotic (HR, 1.31; 95% CI, 1.18-1.44) and to the specific prophylaxis agent (HR, 2.01; 95% CI, 1.80-2.24) was higher in patients receiving prophylaxis. While the overall risk of antibiotic-related complications was similar between groups (HR, 1.08; 95% CI, .94-1.22), the risk of Clostridioidesdifficile and general medication adverse events was higher in prophylaxis recipients (HR [95% CI], 1.56 [1.05-2.23] and 1.62 [1.11-2.29], respectively).

CONCLUSIONS

Among older adults with UTI, the harms of long-term antibiotic prophylaxis may outweigh their benefits.

A Call for Caution in Use of Pertussis Vaccine Effectiveness Studies to Estimate Waning Immunity: A Canadian Immunization Research Network Study

BACKGROUND

Vaccine effectiveness (VE) studies provide essential evidence on waning vaccine-derived immunity, a major threat to pertussis control. We evaluated how study design affects estimates by comparing 2 case-control studies conducted in Ontario, Canada.

METHODS

We compared results from a test-negative design (TND) with a frequency-matched design (FMD) case-control study using pertussis cases from 2005-2015. In the first study, we identified test-negative controls from the public health laboratory that diagnosed cases and, in the second, randomly selected controls from patients attending the same physicians that reported cases, frequency matched on age and year. We compared characteristics of cases and controls using standardized differences.

RESULTS

In both designs, VE estimates for the early years postimmunization were consistent with clinical trials (TND, 84%; FMD, 89% at 1-3 years postvaccination) but diverged as time since last vaccination increased (TND, 41%; FMD, 74% by 8 years postvaccination). Overall, we observed lower VE and faster waning in the TND than the FMD. In the TND but not FMD, controls differed from cases in important confounders, being younger, having more comorbidities, and higher healthcare use. Differences between the controls of each design were greater than differences between cases. TND controls were more likely to be unvaccinated or incompletely vaccinated than FMD controls (P < .001).

CONCLUSIONS

The FMD adjusted better for healthcare-seeking behavior than the TND. Duration of protection from pertussis vaccines is unclear because estimates vary by study design. Caution should be exercised by experts, researchers, and decision makers when evaluating evidence on optimal timing of boosters.

Prenatal hepatitis B screening, and hepatitis B burden among children, in Ontario: a descriptive study

BACKGROUND

Ontario is 1 of 5 provinces that immunize adolescents for hepatitis B virus (HBV), despite the World Health Organization recommendation for universal birth dose vaccination. One rationale for not vaccinating at birth is that universal prenatal screening and related interventions prevent vertical transmission. The aims of our study were to evaluate the uptake and epidemiology of prenatal HBV screening, and to determine the number of children in Ontario with a diagnosis of HBV before adolescent vaccination.

METHODS

We extracted data from ICES, Public Health Ontario and Better Outcomes & Registry Network (BORN) Ontario databases. We assessed prenatal screening uptake and prevalence of prenatal hepatitis B surface antigen (HBsAg) from 2012 to 2016, as well as subsequent hepatitis B e-antigen (HBeAg) and HBV DNA testing and percent positivity. We used age and region to subcategorize the results. In a separate unlinked analysis, we evaluated the number of children positive for HBV aged 0-11 years who were born in Ontario from 2003 to 2013.

RESULTS

From 2012 to 2016, 93% of pregnant women were screened for HBV, with an HBsAg prevalence of 0.6%. Prevalence of HBsAg increased with age, peaking at older than 45 years at 3%. North Toronto had the highest overall prevalence of 1.5%, whereas northern Ontario had the lowest. Of women who were HBsAg positive, HBeAg and HBV DNA tests were subsequently ordered in 13% and 38%, respectively. Of children born in Ontario between 2003 and 2013, 139 of 23 759 tested positive for HBV.

INTERPRETATION

Prenatal HBV screening is not universal and subsequent evaluation is poor, limiting optimal intervention and possibly contributing to some Ontario-born children being given a diagnosis of HBV before age 12 years. These findings underscore the limitations of the province's adolescent vaccination strategy.

Abstract PS3-17: Patient and provider determinants of breast cancer screening among Ontario women age 40-49: A population based retrospective cohort study

Background: For women aged 40-49, Canadian guidelines recommend individualized-decision making (based on risk assessment, values, and preferences) rather than routine screening mammography (SM). In this age group, family physicians are the gatekeepers to access SM; however, studies indicate substantial variability in practice patterns. There are few population-based data regarding uptake and patient/provider determinants of SM in this age group. We describe the uptake and frequency of SM and identify patient and provider level associations with SM in Ontario women aged 40-49. We hypothesized that SM would vary by provider characteristics and women’s demographics, suggesting lack of guideline-concordant care.

Methods: This population-based retrospective cohort study linked health administrative databases to form a cohort of all Ontario women aged 40-49 between April 1, 2009 to March 31, 2019. Mammograms were identified using Ontario Health Billing codes. In order to identify mammograms that were specifically for screening, women were excluded if they had any prior breast MRI, mammogram, cancer diagnosis, oncologist visit, or breast surgical procedure. Sub-cohorts were created to identify women who had (a) at least one SM (“screen cohort”) and (b) 3 or more SM (“routine screen cohort”). Following SM, women were censored from cohorts if they had any cancer diagnosis, breast surgical procedure, oncologist visit, or death; however, breast cancer related outcomes were tracked for 6 months following SM, regardless of whether a censoring event occurred. Patient and provider characteristics were extracted for women in each cohort. A multivariable regression model was used to identify predictors of routine SM.

Results: Of 2 million eligible women, 743 274 (35.6%) received a mammogram, 532 782 (25.5%) received at least one SM, and 90 651 (4.3%) received routine SM (3 or more). Table 1 demonstrates cohort characteristics. There were 0.32 and 0.52 mammograms per woman per year in the screen and routine screen cohort respectively. Call-backs were similar for women after the first SM compared to the third SM (9.5% vs 9.3%); however, there were more biopsies (3.2% vs 1.8%) and breast cancers diagnosed (1.2% vs 0.45%) within six months of the first SM. Compared to the full cohort, women in the routine screen cohort were more likely to have a family physician at cohort entry, be in higher-income quintiles, receive annual health exams, and receive have pap smears (p&lt;0.001). Women in the screen cohort were more likely to have female providers and providers that were primarily paid fee for service versus capitation (p&lt;0.001). Multivariable analysis will be reported at the meeting.

Conclusions: Less than 5% of Ontario women 40-49 undergo routine SM. SM is associated with patient demographics related to higher socioeconomic status which could be related to higher risk of breast cancer and/or increased access to care. SM is also associated with some provider demographics which could be independent of breast cancer risk, suggesting lack of individualized risk assessment. Qualitative work is ongoing to explore this hypothesis. This information can inform guideline implementation strategies.

Table 1: Patient and Provider Characteristics of ScreeningCharacteristicpercent (%) unless otherwise notedAll Women 40-49Screen Cohort (1 or more SM)Routine Screen Cohort (3 or more SM)Patient CharacteristicsAge at Cohort entryMean (median)42.5 (40)42.8 (42)41.7 (41)Age at Cohort exitMean (median)47.3 (50)48.5 (50)49.1 (50)Family Physician at Cohort entry90.0 %92.3%94.8%Income – top quintile20.7%22.3%24%Rurality Category – most urban76.3%79.0%81.2%Birth Location – Canada74.4%72.2%71.6%Annual Health Exams: at least one51.1%72.1%75.3%Pap Smear: at least one68.4%86.6%92.9%Provider CharacteristicsFemale44.8%47.2%52.1%Canadian Graduates70.3%70.3%72.1%Fee for Service model48.0%55.0%58.8%

Citation Format: Michelle B Nadler, Alex Marchand-Austin, Peter C. Austin, Alexandra Desnoyers, Brooke E. Wilson, Aisha Lofters, Noah Ivers, Eitan Amir. Patient and provider determinants of breast cancer screening among Ontario women age 40-49: A population based retrospective cohort study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS3-17.

Underutilization of nontuberculous mycobacterial drug susceptibility testing in Ontario, Canada, 2010-2015

BACKGROUND

Drug susceptibility testing (DST) in nontuberculous mycobacterial pulmonary disease (NTM-PD) is useful for some Mycobacterium species. International guidelines recommend routine use of DST for clinically relevant mycobacteria. DST use and results are poorly studied at the population level. We sought to identify the frequency of DST utilization for nontuberculous mycobacteria (NTMs) and describe the potential relevance of these results in Ontario.

METHODS

Using public health laboratory data, we performed a population-based retrospective analysis of NTM DST utilization in Ontario from May 2010 to June 2015. We determined the proportion of incident NTM-PD infections for which DST was performed and analyzed minimum inhibitory concentration (MIC) distributions from NTM testing overall, using thresholds recommended by the Clinical and Laboratory Standards Institute.

RESULTS

The proportion of incident cases of NTM-PD tested for DST was 6.3% (240/3,806) for Mycobacterium avium complex (MAC), 36.2% (67/185) for M. abscessus, and 1.8% (19/1,057) for M. xenopi. Among specimens from all body sites, MAC resistance to clarithromycin occurred in 8.0% of specimens (21/262) and MAC resistance to amikacin (intravenous, MIC > 64 µg/mL) occurred in 22.6% (19/84). M. abscessus resistance occurred as follows: to amikacin, 3.8% (3/79); cefoxitin, 14.0% (11/79); imipenem, 30.4% (14/46); linezolid, 39.2% (31/79); clarithromycin, 54.2% (13/24); ciprofloxacin, 92.4% (73/79); and moxifloxacin, 91.1% (51/56). M. xenopi analysis was limited by few DST requests and a lack of DST clinical correlation.

CONCLUSIONS

We found that NTM DST is underutilized in Ontario and observed a very high frequency of amikacin resistance among MAC isolates.

Prescribing Patterns for Treatment of Mycobacterium avium Complex and M. xenopi Pulmonary Disease in Ontario, Canada, 2001-2013

Surveys suggest that clinicians diverge from guidelines when treating Mycobacterium avium complex (MAC) pulmonary disease (PD). To determine prescribing patterns, we conducted a cohort study of adults >66 years of age in Ontario, Canada, with MAC or Mycobacterium xenopi PD during 2001-2013. Using linked laboratory and health administrative databases, we studied the first treatment episode (>60 continuous days of >1 of a macrolide, ethambutol, rifamycin, fluoroquinolone, linezolid, inhaled amikacin, or, for M. xenopi, isoniazid). Treatment was prescribed for 24% MAC and 15% of M. xenopi PD patients. Most commonly prescribed was the recommended combination of macrolide, ethambutol, and rifamycin, for 47% of MAC and 36% of M. xenopi PD patients. Among MAC PD patients, 20% received macrolide monotherapy and 33% received regimens associated with emergent macrolide resistance. Although the most commonly prescribed regimen was guidelines-recommended, many regimens prescribed for MAC PD were associated with emergent macrolide resistance.

The direct healthcare costs attributable to West Nile virus illness in Ontario, Canada: a population-based cohort study using laboratory and health administrative data

Background

West Nile virus (WNV) is a mosquito-borne flavivirus, first detected in the Western Hemisphere in 1999 and spread across North America over the next decade. Though endemic in the most populous areas of North America, few studies have estimated the healthcare costs associated with WNV. The objective of this study was to determine direct healthcare costs attributable to WNV illness in Ontario, Canada.

Methods

We conducted a cost-of-illness study on incident laboratory confirmed and probable WNV infected subjects identified from the provincial laboratory database from Jan 1, 2002 through Dec 31, 2012. Infected subjects were linked to health administrative data and matched to uninfected subjects. We used phase-of-care methods to calculate costs for 3 phases of illness: acute infection, continuing care, and final care prior to death. Mean 10-day attributable costs were reported in 2014 Canadian dollars, per capita. Sensitivity analysis was conducted to test the impact of WNV neurologic syndromes on healthcare costs.

Results

One thousand five hundred fifty-one laboratory confirmed and probable WNV infected subjects were ascertained; 1540 (99.3%) were matched to uninfected subjects. Mean age of WNV infected subjects was 49.1 ± 18.4 years, 50.5% were female. Mean costs attributable to WNV were $1177 (95% CI: $1001, $1352) for acute infection, $180 (95% CI: $122, $238) for continuing care, $11,614 (95% CI: $5916, $17,313) for final care - acute death, and $3199 (95% CI: $1770, $4627) for final care - late death. Expected 1-year costs were $13,648, adjusted for survival. Three hundred seventeen infected subjects were diagnosed with at least one neurologic syndrome and greatest healthcare costs in acute infection were associated with encephalitis ($4710, 95% CI: $3770, $5650).

Conclusions

WNV is associated with increased healthcare resource utilization across all phases of care. High-quality studies are needed to understand the health system impact of vector-borne diseases and evaluate the cost effectiveness of novel WNV interventions.

The evolving nature of Bordetella pertussis in Ontario, Canada, 2009-2017: strains with shifting genotypes and pertactin deficiency

This study examined the evolving nature of Bordetella pertussis in Ontario, Canada, by characterizing isolates for their genotypes and expression of pertactin (PRN). From 2009 to 2017, 413 B. pertussis were cultured from pertussis cases at the Public Health Ontario Laboratory. Their genotypes were determined by partial gene sequence analysis of their virulence and (or) vaccine antigens: filamentous haemagglutinin, PRN, fimbriae 3, and pertussis toxin, including the promoter region. Expression of PRN was measured by Western immunoblot. Two predominant genotypes, ST-1 and ST-2, were found throughout the study and were responsible for 47.5% and 46.3% of all case isolates, respectively. The prevalence of ST-1 appeared to fluctuate from 80.3% in 2009 to 20.0% in 2014 and 58.5% in 2017, while the prevalence of ST-2 changed from 18.4% in 2009 to 80.0% in 2014 and 26.2% in 2017. A PRN-deficient strain was first noted in 2011 (16.7%), and its prevalence increased to 70.8% in 2016 but decreased to 46.2% in 2017. More ST-2 (46.6%) than ST-1 (16.8%) strains were associated with PRN deficiency. Newer ST-21 and ST-22 found in 2015-2017 were uniformly PRN deficient. The impact of the evolving nature of B. pertussis on disease epidemiology requires further longitudinal studies.

Cohort profile: Development and profile of a population-based, retrospective cohort of diagnosed people living with HIV in Ontario, Canada (Ontario HIV Laboratory Cohort)

PURPOSE

Population-based cohorts of diagnosed people living with HIV (PLWH) are limited worldwide. In Ontario, linked HIV diagnostic and viral load (VL) test databases are centralised and contain laboratory data commonly used to measure engagement in HIV care. We used these linked databases to create a population-based, retrospective cohort of diagnosed PLWH in Ontario, Canada.

PARTICIPANTS

A datamart was created by integrating diagnostic and VL databases and linking records at the individual level. These databases contain information on laboratory test results and sociodemographic/clinical information collected on requisition/surveillance forms. Datamart individuals enter our cohort with the first record of a nominal HIV-positive diagnostic test (1985-2015) or VL test (1996-2015), and remain unless administratively lost to follow-up (LTFU; no VL test for >2 years and no VL test in later years). Non-nominal diagnostic tests are excluded as they lack identifying information to permit linkage to other tests. However, individuals diagnosed non-nominally are included in the cohort with record of a VL test. The LTFU rule is applied to indirectly censor for death/out-migration.

FINDINGS TO DATE

As of the end of 2015, the datamart contained 40 372 HIV-positive diagnostic tests and 23 851 individuals with ≥1 VL test. Almost half (46.3%) of the diagnostic tests were non-nominal and excluded, although this was lower (~15%) in recent years. Overall, 29 587 individuals have entered the cohort-contributing 229 302 person-years of follow-up since 1996. Between 2000 and 2015, the number of diagnosed PLWH (cohort individuals not LTFU) increased from 8859 to 16 110, and the percent who were aged ≥45 years increased from 29.1% to 62.6%. The percent of diagnosed PLWH who were virally suppressed (<200 copies/mL) increased from 40.7% in 2000 to 79.5% in 2015.

FUTURE PLANS

We plan to conduct further analyses of HIV care engagement and link to administrative databases with information on death, migration, physician billing claims and prescriptions. Linkage to other data sources will address cohort limitations and expand research opportunities.

Universal genotyping reveals province-level differences in the molecular epidemiology of tuberculosis

OBJECTIVES

Compare the molecular epidemiology of tuberculosis (TB) between two large Canadian provinces-Ontario and British Columbia (BC)-to identify genotypic clusters within and across both provinces, allowing for an improved understanding of genotype data and providing context to more accurately identify clusters representing local transmission.

DESIGN

We compared 24-locus Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats (MIRU-VNTR) genotyping for 3,314 Ontario and 1,602 BC clinical Mycobacterium tuberculosis isolates collected from 2008 through 2014. Laboratory data for each isolate was linked to case-level records to obtain clinical and demographic data.

RESULTS

The demographic characteristics of persons with TB varied between provinces, most notably in the proportion of persons born outside Canada, which was reflected in the large number of unique genotypes (n = 3,461). The proportion of clustered isolates was significantly higher in BC. Substantial clustering amongst non-Lineage 4 TB strains was observed within and across the provinces. Only two large clusters (≥10 cases/cluster) representing within province transmission had interprovincial genotype matches.

CONCLUSION

We recommend expanding analysis of shared genotypes to include neighbouring jurisdictions, and implementing whole genome sequencing to improve identification of TB transmission, recognize outbreaks, and monitor changing trends in TB epidemiology.

Trends in HIV care cascade engagement among diagnosed people living with HIV in Ontario, Canada: A retrospective, population-based cohort study

Background

The HIV cascade is an important framework for assessing systems of care, but population-based assessment is lacking for most jurisdictions worldwide. We measured cascade indicators over time in a population-based cohort of diagnosed people living with HIV (PLWH) in Ontario, Canada.

Methods

We created a retrospective cohort of diagnosed PLWH using a centralized laboratory database with HIV diagnostic and viral load (VL) test records linked at the individual-level. Individuals enter the cohort with record of a nominal HIV-positive diagnostic test or VL test, and remain unless administratively lost to follow-up (LTFU, >2 consecutive years with no VL test and no VL test in later years). We calculated the annual percent of diagnosed PLWH (cohort individuals not LTFU) between 2000 and 2015 who were in care (≥1 VL test), on ART (as documented on VL test requisition) or virally suppressed (<200 copies/ml). We also calculated time from diagnosis to linkage to care and viral suppression among individuals newly diagnosed with HIV. Analyses were stratified by sex and age. Upper/lower bounds were calculated using alternative indicator definitions.

Results

The number of diagnosed PLWH increased from 8,859 (8,859–11,389) in 2000 to 16,110 (16,110–17,423) in 2015. Over this 16-year period, the percent of diagnosed PLWH who were: in care increased from 81% (63–81%) to 87% (81–87%), on ART increased from 55% (34–60%) to 81% (70–82%) and virally suppressed increased from 41% (23–46%) to 80% (67–81%). Between 2000 and 2014, the percent of newly diagnosed individuals who linked to care within three months of diagnosis or achieved viral suppression within six months of diagnosis increased from 67% to 82% and from 22% to 42%, respectively. Estimates were generally lower for females and younger individuals.

Discussion

HIV cascade indicators among diagnosed PLWH in Ontario improved between 2000 and 2015, but gaps still remain—particularly for younger individuals.

A method for improved fluorescent staining for acid fast smear microscopy by incorporating an acetone rinse step

Microscopic examination of the specimen smear for acid fast bacilli (AFB) provides a simple and rapid means of detecting AFB using fluorescent stain methods and remains a valuable diagnostic test used worldwide to identify and manage suspect cases of tuberculosis (TB). Methods to improve AFB smear staining protocols could provide better detection of suspect TB cases. In particular, decreasing background debris may improve the detection of smears with low numbers of bacilli. We assessed staining by the standard rack method compared to bulk container staining using an acetone rinse step to decrease background debris. No cross-contamination was observed in the bulk container staining, and higher accuracy with less reading time was achieved with the acetone rinse. Most importantly, more bacilli were detected per positive smear using the acetone rinse method.

Pulmonary versus Nonpulmonary Nontuberculous Mycobacteria, Ontario, Canada

In Ontario, Canada, during 1998–2010, nontuberculous mycobacteria (NTM) from pulmonary sites comprised 96% of species/patient combinations isolated; annual rates of isolation and cases increased steadily. NTM isolates from nonpulmonary sites comprised 4% of species/patient combinations; annual rates and cases were temporally stable. NTM increases were driven exclusively by pulmonary isolates and disease.

Under-reporting of pertussis in Ontario: A Canadian Immunization Research Network (CIRN) study using capture-recapture

Introduction

Under-reporting of pertussis cases is a longstanding challenge. We estimated the true number of pertussis cases in Ontario using multiple data sources, and evaluated the completeness of each source.

Methods

We linked data from multiple sources for the period 2009 to 2015: public health reportable disease surveillance data, public health laboratory data, and health administrative data (hospitalizations, emergency department visits, and physician office visits). To estimate the total number of pertussis cases in Ontario, we used a three-source capture-recapture analysis stratified by age (infants, or aged one year and older) and adjusting for dependency between sources. We used the Bayesian Information Criterion to compare models.

Results

Using probable and confirmed reported cases, laboratory data, and combined hospitalizations/emergency department visits, the estimated total number of cases during the six-year period amongst infants was 924, compared with 545 unique observed cases from all sources. Using the same sources, the estimated total for those aged 1 year and older was 12,883, compared with 3,304 observed cases from all sources. Only 37% of infants and 11% for those aged 1 year and over admitted to hospital or seen in an emergency department for pertussis were reported to public health. Public health reporting sensitivity varied from 2% to 68% depending on age group and the combination of data sources included. Sensitivity of combined hospitalizations and emergency department visits varied from 37% to 49% and of laboratory data from 1% to 50%.

Conclusions

All data sources contribute cases and are complementary, suggesting that the incidence of pertussis is substantially higher than suggested by routine reports. The sensitivity of different data sources varies. Better case identification is required to improve pertussis control in Ontario.

Pulmonary Nontuberculous Mycobacteria-Associated Deaths, Ontario, Canada, 2001-2013

Survival implications of nontuberculous mycobacterial pulmonary disease (NTM-PD) and NTM pulmonary isolation without disease (NTM-PI) are unclear. To study deaths associated with NTM-PD and NTM-PI and differences in survival between them, we conducted a population-based cohort study of persons with microbiologically defined NTM-PD or NTM-PI diagnosed during 2001–2013 in Ontario, Canada. We used propensity score matching and Cox proportional hazards models to compare survival. Among 9,681 NTM-PD patients and 10,936 NTM-PI patients, 87% and 91%, respectively, were successfully matched with unexposed controls. Both NTM-PD and NTM-PI were associated with higher rates of death for all species combined and for most individual species. Compared with NTM-PI, NTM-PD was associated with higher death rates for all species combined, Mycobacterium avium complex, and M. xenopi. NTM-PD and NTM-PI were significantly associated with death, NTM-PD more so than NTM-PI.

Limitations of administrative data to identify measles cases in Ontario, Canada: a cautionary tale

OBJECTIVE

To explore the utility of laboratory data and determine the validity of healthcare administrative data for describing the frequency of measles in Ontario.

METHODS

We linked Ontario healthcare utilization administrative data to Public Health Ontario (PHO) laboratory data from 01 January 2006 to 30 November 2012.

RESULTS

The sensitivity of the administrative data was 54% and the positive predictive value was 1% when compared with 50 cases identified in laboratory data as a gold standard.

CONCLUSIONS

As measles is no longer endemic in Ontario, the high number of measles-coded healthcare visits found in Ontario health administration data exceeds the true number of cases. Great caution should be taken in using administrative data to calculate the incidence of measles in areas where it has been eliminated.

Technology and tuberculosis control: the OUT-TB Web experience

Objective

Develop a tool to disseminate integrated laboratory, clinical, and demographic case data necessary for improved contact tracing and outbreak detection of tuberculosis (TB).

Methods

In 2007, the Public Health Ontario Laboratories implemented a universal genotyping program to monitor the spread of TB strains within Ontario. Ontario Universal Typing of TB (OUT-TB) Web utilizes geographic information system (GIS) technology with a relational database platform, allowing TB control staff to visualize genotyping matches and microbiological data within the context of relevant epidemiological and demographic data.

Results

OUT-TB Web is currently available to the 8 health units responsible for >85% of Ontario's TB cases and is a valuable tool for TB case investigation. Users identified key features to implement for application enhancements, including an e-mail alert function, customizable heat maps for visualizing TB and drug-resistant cases, socioeconomic map layers, a dashboard providing TB surveillance metrics, and a feature for animating the geographic spread of strains over time.

Conclusion

OUT-TB Web has proven to be an award-winning application and a useful tool. Developed and enhanced using regular user feedback, future versions will include additional data sources, enhanced map and line-list filter capabilities, and development of a mobile app.

Case-control study of household contacts to examine immunological protection from Bordetella pertussis transmission - study protocol

BACKGROUND

There is mounting evidence that the recent resurgence of pertussis in many countries is in part related to the acellular vaccine, which has been administered in Canada since 1997. This vaccine elicits a different cell-mediated immune response than the previously used whole-cell vaccine, and its effectiveness wanes over time. The aim of this study is to understand the immunological, demographic and clinical factors that mediate protection from pertussis on exposure.

METHODS

This is a household case-control study protocol. Following notification of an index case in a household, a study team will conduct a home visit to collect data and biological specimens. The study team will return to the household 8 weeks from the onset of illness in the index case. The Th1, Th2 and Th17 responses, cytokine expression, IgG subclass, blood cell counts and presence of Bordetella pertussis will be determined. We will use laboratory and statistical analyses to determine immunological differences between contacts who are infected with B. pertussis and contacts who remain healthy, and to determine which clinical and demographic covariates are associated with a reduced risk of infection.

INTERPRETATION

The results of this study will be essential for understanding the immune response required for protection from infection with B. pertussis and will contribute to our understanding of the shortcomings of the current vaccine.

The risk of mycobacterial infections associated with inhaled corticosteroid use

Inhaled corticosteroid (ICS) use is associated with an increased risk of pneumonia. This study was performed to determine if ICS use is associated with an increased risk of nontuberculous mycobacterial pulmonary disease (NTM-PD) or tuberculosis (TB).We conducted a population-based nested case-control study using linked laboratory and health administrative databases in Ontario, Canada, including adults aged ≥66 years with treated obstructive lung disease (i.e. asthma, chronic obstructive pulmonary disease (COPD) or asthma-COPD overlap syndrome) between 2001 and 2013. We estimated odds ratios comparing ICS use with nonuse among NTM-PD and TB cases and controls using conditional logistic regression.Among 417 494 older adults with treated obstructive lung disease, we identified 2966 cases of NTM-PD and 327 cases of TB. Current ICS use was associated with NTM-PD compared with nonuse (adjusted OR (aOR) 1.86, 95% CI 1.60-2.15) and was statistically significant for fluticasone (aOR 2.09, 95% CI 1.80-2.43), but not for budesonide (aOR 1.19, 95% CI 0.97-1.45). There was a strong dose-response relationship between incident NTM-PD and cumulative ICS dose over 1 year. There was no significant association between current ICS use and TB (aOR 1.43, 95% CI 0.95-2.16).This study suggests that ICS use is associated with an increased risk of NTM-PD, but not TB.

High Incidence of Invasive Group A Streptococcal Infections in Remote Indigenous Communities in Northwestern Ontario, Canada

Background

Worldwide, indigenous populations appear to be at increased risk for invasive group A streptococcal (iGAS) infections. Although there is empirical evidence that the burden of iGAS disease is significant among remote First Nations communities in Northwestern Ontario, Canada, the epidemiology of iGAS infections in the area remains poorly characterized.

Methods

Individuals that met case definition for iGAS disease and whose laboratory specimens were processed by Meno Ya Win Health Centre in Sioux Lookout, Canada or who were reported to Thunder Bay District Health Unit, Canada were identified for the period 2009 to 2014. Case demographics, clinical severity, comorbidities, and risk factors were collected through chart review. Strain typing and antibiotic susceptibility were determined when possible. Basic descriptive statistics were calculated.

Results

Sixty-five cases of iGAS disease were identified, for an annualized incidence of 56.2 per 100 000. Primary bacteremia was present in 26.2% of cases, and cellulitis was identified in 55.4% of cases. The most common comorbidities identified were diabetes (38.5%) and skin conditions (38.5%). Prevalent risk factors included alcohol dependence (25%). Fourteen different emm types were identified among 42 isolates, with the most common being emm114 (17.4%), emm11 (15.2%), and emm118 (13.0%). Resistance to erythromycin and clindamycin was found in 24.6% of isolates.

Conclusions

Rural and remote First Nations communities in Northwestern Ontario experience iGAS infections at a rate 10 times the provincial and national average. Compared with other North American series, a lower proportion of isolates causing infection were of emm types included in candidate GAS vaccines.

Effectiveness of pertussis vaccination and duration of immunity

BACKGROUND

A resurgence of pertussis cases among both vaccinated and unvaccinated people raises questions about vaccine effectiveness over time. Our objective was to study the effectiveness of the pertussis vaccine and characterize the effect of waning immunity and whole-cell vaccine priming.

METHODS

We used the test-negative design, a nested case-control study with test-negative individuals as controls. We constructed multivariable logistic regression models to estimate odds ratios (ORs). Vaccine effectiveness was calculated as (1 - OR) × 100. We assessed waning immunity by calculating the odds of developing pertussis per year since last vaccination and evaluated the relative effectiveness of priming with acellular versus whole-cell vaccine.

RESULTS

Between Dec. 7, 2009, and Mar. 31, 2013, data on 5867 individuals (486 test-positive cases and 5381 test-negative controls) were available for analysis. Adjusted vaccine effectiveness was 80% (95% confidence interval [CI] 71% to 86%) at 15-364 days, 84% (95% CI 77% to 89%) at 1-3 years, 62% (95% CI 42% to 75%) at 4-7 years and 41% (95% CI 0% to 66%) at 8 or more years since last vaccination. We observed waning immunity with the acellular vaccine, with an adjusted OR for pertussis infection of 1.27 (95% CI 1.20 to 1.34) per year since last vaccination. Acellular, versus whole-cell, vaccine priming was associated with an increased odds of pertussis (adjusted OR 2.15, 95% CI 1.30 to 3.57).

INTERPRETATION

We observed high early effectiveness of the pertussis vaccine that rapidly declined as time since last vaccination surpassed 4 years, particularly with acellular vaccine priming. Considering whole-cell vaccine priming and/or boosters in pregnancy to optimize pertussis control may be prudent.

Data-driven approach of CUSUM algorithm in temporal aberrant event detection using interactive web applications

OBJECTIVE

In 2014/2015, Public Health Ontario developed disease-specific, cumulative sum (CUSUM)-based statistical algorithms for detecting aberrant increases in reportable infectious disease incidence in Ontario. The objective of this study was to determine whether the prospective application of these CUSUM algorithms, based on historical patterns, have improved specificity and sensitivity compared to the currently used Early Aberration Reporting System (EARS) algorithm, developed by the US Centers for Disease Control and Prevention.

METHOD

A total of seven algorithms were developed for the following diseases: cyclosporiasis, giardiasis, influenza (one each for type A and type B), mumps, pertussis, invasive pneumococcal disease. Historical data were used as baseline to assess known outbreaks. Regression models were used to model seasonality and CUSUM was applied to the difference between observed and expected counts. An interactive web application was developed allowing program staff to directly interact with data and tune the parameters of CUSUM algorithms using their expertise on the epidemiology of each disease. Using these parameters, a CUSUM detection system was applied prospectively and the results were compared to the outputs generated by EARS. The outcome was the detection of outbreaks, or the start of a known seasonal increase and predicting the peak in activity.

RESULTS

The CUSUM algorithms detected provincial outbreaks earlier than the EARS algorithm, identified the start of the influenza season in advance of traditional methods, and had fewer false positive alerts. Additionally, having staff involved in the creation of the algorithms improved their understanding of the algorithms and improved use in practice.

CONCLUSION

Using interactive web-based technology to tune CUSUM improved the sensitivity and specificity of detection algorithms.

Acute Respiratory Infections in Travelers Returning from MERS-CoV-Affected Areas

We examined which respiratory pathogens were identified during screening for Middle East respiratory syndrome coronavirus in 177 symptomatic travelers returning to Ontario, Canada, from regions affected by the virus. Influenza A and B viruses (23.1%) and rhinovirus (19.8%) were the most common pathogens identified among these travelers.

Epidemiology of Enterovirus D68 in Ontario

In August 2014, children's hospitals in Kansas City, Missouri and Chicago, Illinois notified the Centers for Disease Control and Prevention (CDC) about increased numbers of pediatric patients hospitalized with severe respiratory illness (SRI). In response to CDC reports, Public Health Ontario Laboratories (PHOL) launched an investigation of patients being tested for enterovirus D-68 (EV-D68) in Ontario, Canada. The purpose of this investigation was to enhance our understanding of EV-D68 epidemiology and clinical features. Data for this study included specimens submitted for EV-D68 testing at PHOL from September 1, 2014 to October 31, 2014. Comparisons were made between patients who tested positive for the virus (cases) and those testing negative (controls). EV-D68 was identified in 153/907 (16.8%) of patients tested. In the logistic regression model adjusting for age, sex, setting and time to specimen collection, individuals younger than 20 years of age were more likely to be diagnosed with EV-D68 compared to those 20 and over, with peak positivity at ages 5-9 years. Cases were not more likely to be hospitalized than controls. Cases were more likely to be identified in September than October (OR 8.07; 95% CI 5.15 to 12.64). Routine viral culture and multiplex PCR were inadequate methods to identify EV-D68 due to poor sensitivity and inability to differentiate EV-D68 from other enterovirus serotypes or rhinovirus. Testing for EV-D68 in Ontario from July to December, 2014 detected the presence of EV-D68 virus among young children during September-October, 2014, with most cases detected in September. There was no difference in hospitalization status between cases and controls. In order to better understand the epidemiology of this virus, surveillance for EV-D68 should include testing of symptomatic individuals from all treatment settings and patient age groups, with collection and analysis of comprehensive clinical and epidemiological data.

Correlation of Real Time PCR Cycle Threshold Cut-Off with Bordetella pertussis Clinical Severity

Bordetella pertussis testing performed using real-time polymerase chain reaction (RT-PCR) is interpreted based on a cycle threshold (Ct) value. At Public Health Ontario Laboratories (PHOL), a Ct value <36 is reported as positive, and Ct values ≥36 and <40 are reported as indeterminate. PHOL reported indeterminate results to physicians and public health units until May 2012, after which these results were only reported to physicians. We investigated the association between Ct value and disease symptom and severity to examine the significance of indeterminate results clinically, epidemiologically and for public health reporting. B. pertussis positive and indeterminate RT-PCR results were linked to pertussis cases reported in the provincial Integrated Public Health Information System (iPHIS), using deterministic linkage. Patients with positive RT-PCR results had a lower median age of 10.8 years compared to 12.0 years for patients with indeterminate results (p = 0.24). Hospitalized patients had significantly lower Ct values than non-hospitalized patients (median Ct values of 20.7 vs. 31.6, p<0.001). The proportion of patients reporting the most indicative symptoms of pertussis did not differ between patients with positive vs. indeterminate RT-PCR results. Taking the most indicative symptoms of pertussis as the gold-standard, the positive predictive value of the RT-PCR test was 68.1%. RT-PCR test results should be interpreted in the context of the clinical symptoms, age, vaccination status, prevalence, and other factors. Further information on interpretation of indeterminate RT-PCR results may be needed, and the utility of reporting to public health practitioners should be re-evaluated.

Increased risk of mycobacterial infections associated with anti-rheumatic medications

RATIONALE

Anti-tumour necrosis factor (TNF) agents and other anti-rheumatic medications increase the risk of TB in rheumatoid arthritis (RA). Whether they increase the risk of infections with nontuberculous mycobacteria (NTM) is uncertain.

OBJECTIVES

To determine the effect of anti-TNF therapy and other anti-rheumatic drugs on the risk of NTM disease and TB in older patients with RA.

METHODS

Population-based nested case-control study among Ontario seniors aged ≥67 years with RA who were prescribed at least one anti-rheumatic medication between 2001 and 2011. We identified cases of TB and NTM disease microbiologically and identified drug exposures using linked prescription drug claims. We estimated ORs using conditional logistic regression, controlling for several potential confounders.

MEASUREMENTS AND MAIN RESULTS

Among 56 269 older adults with RA, we identified 37 cases of TB and 211 cases of NTM disease; each case was matched to up to 10 controls. Individuals with TB or NTM disease were both more likely to be using anti-TNF therapy (compared with non-use); adjusted ORs (95% CIs) were 5.04 (1.27 to 20.0) and 2.19 (1.10 to 4.37), respectively. Exposure to leflunomide and other anti-rheumatic drugs with high immunosuppressing potential also were associated with both TB and NTM disease, while oral corticosteroids and hydroxychloroquine were associated with NTM disease.

CONCLUSIONS

Anti-TNF use is associated with increased risk of both TB and NTM disease, but appears to be a relatively greater risk for TB. Several other anti-rheumatic drugs were also associated with mycobacterial infections.

Human metapneumovirus prevalence and molecular epidemiology in respiratory outbreaks in Ontario, Canada

Human metapneumovirus (hMPV) has been identified previously as a cause of respiratory outbreaks in adults, including the elderly. The objective of this study was to document respiratory outbreaks that were caused by hMPV in Ontario, Canada and to identify the various circulating genotypes during April 2009–February 2012. The majority of the outbreaks that were part of this study were in adults (>65 years). Total nucleic acid extraction was done on 123 residual anonymized clinical specimens from 51 different respiratory outbreaks. Specimens were subjected to PCR amplification and Sanger sequencing targeting the F and G genes of hMPV. Phylogenetic analysis was performed to identify genotypes. HMPV accounted for 195 (8.5%) of 2,292 respiratory outbreaks. Genotype A2b was most prevalent, detected in 28 (54.9%) of 51 typed hMPV‐positive outbreaks. The genotype A2b2 that was described recently was also identified. In earlier reports, subtype A1 was reported in Canada which was absent in the specimens typed in this study. This shift in genotype may be significant in terms of disease severity, and for any future vaccine considerations. Regular testing for hMPV should be done as part of outbreak investigation. J. Med. Virol. 87:269–274, 2015. © 2014 Wiley Periodicals, Inc.

Antimicrobial susceptibility of clinical isolates of anaerobic bacteria in Ontario, 2010-2011

The local epidemiology of antimicrobial susceptibility patterns in anaerobic bacteria is important in guiding the empiric treatment of infections. However, susceptibility data are very limited on anaerobic organisms, particularly among non-Bacteroides organisms. To determine susceptibility profiles of clinically-significant anaerobic bacteria in Ontario Canada, anaerobic isolates from sterile sites submitted to Public Health Ontario Laboratory (PHOL) for identification and susceptibility testing were included in this study. Using the E-test method, isolates were tested for various antimicrobials including, penicillin, cefoxitin, clindamycin, meropenem, piperacillin-tazobactam and metronidazole. The MIC results were interpreted based on guidelines published by Clinical and Laboratory Standards Institute. Of 2527 anaerobic isolates submitted to PHOL, 1412 were either from sterile sites or bronchial lavage, and underwent susceptibility testing. Among Bacteroides fragilis, 98.2%, 24.7%, 1.6%, and 1.2% were resistant to penicillin, clindamycin, piperacillin-tazobactam, and metronidazole, respectively. Clostridium perfringens was universally susceptible to penicillin, piperacillin-tazobactam, and meropenem, whereas 14.2% of other Clostridium spp. were resistant to penicillin. Among Gram-positive anaerobes, Actinomyces spp., Parvimonas micra and Propionibacterium spp. were universally susceptible to β-lactams. Eggerthella spp., Collinsella spp., and Eubacterium spp. showed variable resistance to penicillin. Among Gram-negative anaerobes, Fusobacterium spp., Prevotella spp., and Veillonella spp. showed high resistance to penicillin but were universally susceptible to meropenem and piperacillin-tazobactam. The detection of metronidazole resistant B. fragilis is concerning as occurrence of these isolates is extremely rare. These data highlight the importance of ongoing surveillance to provide clinically relevant information to clinicians for empiric management of infections caused by anaerobic organisms.

Pulmonary nontuberculous mycobacterial disease, Ontario, Canada, 1998-2010

We measured the prevalence and temporal trends of pulmonary nontuberculous mycobacterial disease among residents of Ontario, Canada, during 1998–2010. Five-year prevalence increased from 29.3 cases/100,000 persons in 1998–2002 to 41.3/100,000 in 2006–2010 (p<0.0001). Improved laboratory methods did not explain this increase, suggesting a surge in disease prevalence.

Respiratory viral infections in institutions from late stage of the first and second waves of pandemic influenza A (H1N1) 2009, Ontario, Canada

Please cite this paper as: Asner et al. (2012) Respiratory viral infections in institutions from late stage of the first and second waves of pandemic A (H1N1) 2009, Ontario, Canada. Influenza and Other Respiratory Viruses 6(3), e11–e15.

We report the impact of respiratory viruses on various outbreak settings by using surveillance data from the late first and second wave periods of the 2009 pandemic. A total of 278/345(78·5%) outbreaks tested positive for at least one respiratory virus by multiplex PCR. We detected A(H1N1)pdm09 in 20·6% of all reported outbreaks of which 54·9% were reported by camps, schools, and day cares (CSDs) and 29·6% by long‐term care facilities (LCFTs), whereas enterovirus/human rhinovirus (ENT/HRV) accounted for 62% outbreaks of which 83·7% were reported by long‐term care facilities (LCTFs). ENT/HRV was frequently identified in LTCF outbreaks involving elderly residents, whereas in CSDs, A(H1N1)pdm09 was primarily detected.

Rhinovirus outbreaks in long-term care facilities, Ontario, Canada

Diagnostic difficulties may have led to underestimation of rhinovirus infections in long-term care facilities. Using surveillance data, we found that rhinovirus caused 59% (174/297) of respiratory outbreaks in these facilities during 6 months in 2009. Disease was sometimes severe. Molecular diagnostic testing can differentiate these outbreaks from other infections such as influenza.

Respiratory infection in institutions during early stages of pandemic (H1N1) 2009, Canada

Outbreaks of respiratory infection in institutions in Ontario, Canada were studied from April 20 to June 12, 2009, during the early stages of the emergence of influenza A pandemic (H1N1) 2009. Despite widespread presence of influenza in the general population, only 2 of 83 outbreaks evaluated by molecular methods were associated with pandemic (H1N1) 2009.