Omicron COVID-19 Case Estimates Based on Previous SARS-CoV-2 Wastewater Load, Regional Municipality of Peel, Ontario, Canada.

We determined correlations between SARS-CoV-2 load in untreated water and COVID-19 cases and patient hospitalizations before the Omicron variant (September 2020-November 2021) at 2 wastewater treatment plants in the Regional Municipality of Peel, Ontario, Canada. Using pre-Omicron correlations, we estimated incident COVID-19 cases during Omicron outbreaks (November 2021-June 2022). The strongest correlation between wastewater SARS-CoV-2 load and COVID-19 cases occurred 1 day after sampling (r = 0.911). The strongest correlation between wastewater load and COVID-19 patient hospitalizations occurred 4 days after sampling (r = 0.819). At the peak of the Omicron BA.2 outbreak in April 2022, reported COVID-19 cases were underestimated 19-fold because of changes in clinical testing. Wastewater data provided information for local decision-making and are a useful component of COVID-19 surveillance systems.

Estimating the test-adjusted incidence of Chlamydia trachomatis infections identified through Public Health Ontario Laboratories in Peel region, Ontario, 2010-2018: a population-based study.

BACKGROUND: Public health guidelines for chlamydia testing are not sex specific, but young females test at a disproportionally higher rate than males and other age groups. This study aims to describe testing trends across age and sex subgroups, then estimate a test-adjusted incidence of chlamydia in these subgroups to identify gaps in current testing practices. METHODS: We used a population-based study to examine observed chlamydia rates by age and sex subgroups: 15-19 years, 20-29 years, 30-39 years and older than 40 years. The study included diagnostic test results recorded by Public Health Ontario Laboratories between Jan. 1, 2010, and Dec. 31, 2018, for individuals living in Peel region, Ontario. We then employed meta-regression models as a method of standardization to estimate the effect of sex and age on standardized morbidity ratio, testing ratio and test positivity, then calculate a test-adjusted incidence of chlamydia for each subgroup. RESULTS: Over the study period, infection, testing and test positivity varied across age and sex subgroups. Observed incidence and testing were highest in females aged 20-29 years, whereas males had the highest standardized test positivity across all age groups. After estimating test-adjusted incidence for each age-sex subgroup, males in the 15-19-year and 30-39-year age groups had an increase in incidence of 60.2% and 9.7%, respectively, compared with the observed incidence. INTERPRETATION: We found that estimated test-adjusted incidence was higher than observed incidence in males aged 15-19 years and 30-39 years. This suggests that infections in males are likely being missed owing to differential testing, and this may be contributing to the persistent increase in reported cases in Canada. Public health programming that targets males, especially in high-risk settings and communities, and use of innovative partner notification methods could be critical to curbing overall rates of chlamydia.

Direct Medical Costs of 3 Reportable Travel-Related Infections in Ontario, Canada, 2012-2014.

Immigrants traveling to their birth countries to visit friends or relatives are disproportionately affected by travel-related infections, in part because most preventive travel health services are not publicly funded. To help identify cost-effective policies to reduce this disparity, we measured the medical costs (in 2015 Canadian dollars) of 3 reportable travel-related infectious diseases (hepatitis A, malaria, and enteric fever) that accrued during a 3-year period (2012-2014) in an ethnoculturally diverse region of Canada (Peel, Ontario) by linking reportable disease surveillance and health administrative data. In total, 318 case-patients were included, each matched with 2 controls. Most spending accrued in inpatient settings. Direct healthcare spending totaled $2,058,196; the mean attributable cost per case was $6,098 (95% CI $5,328-$6,868) but varied by disease (range $4,558-$7,852). Costs were greatest for enteric fever. Policies that address financial barriers to preventive health services for high-risk groups should be evaluated.

Accuracy of health administrative data to identify cases of reportable travel or migration-related infectious diseases in Ontario, Canada.

An ongoing challenge of estimating the burden of infectious diseases known to disproportionately affect migrants (e.g. malaria, enteric fever) is that many health information systems, including reportable disease surveillance systems, do not systematically collect data on migrant status and related factors. We explored whether health administrative data linked to immigration records offered a viable alternative for accurately identifying cases of hepatitis A, malaria and enteric fever in Ontario, Canada. Using linked health care databases generated by Ontario's universal health care program, we constructed a cohort of medically-attended individuals with presumed hepatitis A, malaria or enteric fever in Peel region using diagnostic codes. Immigrant status was ascertained using linked immigration data. The sensitivity and positive predictive value (PPV) of diagnostic codes was evaluated through probabilistic linkage of the cohort to Ontario's reportable disease surveillance system (iPHIS) as the reference standard. Linkage was successful in 90.0% (289/321) of iPHIS cases. While sensitivity was high for hepatitis A and enteric fever (85.8% and 83.7%) and moderate for malaria (69.0%), PPV was poor for all diseases (0.3-41.3%). The accuracy of diagnostic codes did not vary by immigrant status. A dated coding system for outpatient physician claims and exclusion of new immigrants not yet eligible for health care were key challenges to using health administrative data to identify cases. Despite this, we show that linkages of health administrative and immigration records with reportable disease surveillance data are feasible and have the potential to bridge important gaps in estimating burden using either data source independently. .

How Can We Keep Immigrant Travelers Healthy? Health Challenges Experienced by Canadian South Asian Travelers Visiting Friends and Relatives.

Immigrant travelers who visit friends and relatives (VFR travelers) experience substantially higher rates of travel-related infections than other travelers, in part due to low uptake of pretravel health advice. While barriers to accessing advice have been identified, better characterization is needed to inform targeted interventions. We sought to understand how South Asian VFR travelers perceived and responded to travel-related health risks by conducting group interviews with 32 adult travelers from an ethnoculturally diverse Canadian region. Travelers positioned themselves as knowledgeable of key health risks, despite not seeking pretravel health advice. Their responses to risks were pragmatic and rooted in experience, but often constrained by competing concerns, including rushed travel, familial obligations, cost, and a desire to preserve authentic experiences. Moving beyond risk awareness to reinforcing the value of medical advice and intervention, in a manner that is sensitive to these unique concerns, is needed when delivering tailored health promotion messages to VFR travelers.

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.

Perceived usefulness of syndromic surveillance in Ontario during the H1N1 pandemic.

BACKGROUND: Despite the growing popularity of syndromic surveillance, little is known about if or how these systems are accepted, utilized and valued by end users. This study seeks to describe the use of syndromic surveillance systems in Ontario and users' perceptions of the value of these systems within the context of other surveillance systems. METHODS: Ontario's 36 public health units, the provincial ministry of health and federal public health agency completed a web survey to identify traditional and syndromic surveillance systems used routinely and during the pandemic and to describe system attributes and utility in monitoring pandemic activity and informing decision-making. RESULTS: Syndromic surveillance systems are used by 20/38 (53%) organizations. For routine surveillance, laboratory, integrated Public Health Information System and school absenteeism data are the most frequently used sources. Laboratory data received the highest ratings for reliability, timeliness and accuracy ('very acceptable' by 92, 51 and 89%). Hospital/clinic screening data were rated as the most reliable and timely syndromic data source (50 and 43%) and ED visit data the most accurate (48%). During the pandemic, laboratory data were considered the most useful for monitoring the epidemiology and informing decision-making while ED screening and visit data were considered the most useful syndromic sources. CONCLUSIONS: End user perceptions are valuable for identifying opportunities for improvement and guiding further investments in public health surveillance.

Assessing secondary attack rates among household contacts at the beginning of the influenza A (H1N1) pandemic in Ontario, Canada, April-June 2009: a prospective, observational study.

BACKGROUND: Understanding transmission dynamics of the pandemic influenza A (H1N1) virus in various exposure settings and determining whether transmissibility differed from seasonal influenza viruses was a priority for decision making on mitigation strategies at the beginning of the pandemic. The objective of this study was to estimate household secondary attack rates for pandemic influenza in a susceptible population where control measures had yet to be implemented. METHODS: All Ontario local health units were invited to participate; seven health units volunteered. For all laboratory-confirmed cases reported between April 24 and June 18, 2009, participating health units performed contact tracing to detect secondary cases among household contacts. In total, 87 cases and 266 household contacts were included in this study. Secondary cases were defined as any household member with new onset of acute respiratory illness (fever or two or more respiratory symptoms) or influenza-like illness (fever plus one additional respiratory symptom). Attack rates were estimated using both case definitions. RESULTS: Secondary attack rates were estimated at 10.3% (95% CI 6.8-14.7) for secondary cases with influenza-like illness and 20.2% (95% CI 15.4-25.6) for secondary cases with acute respiratory illness. For both case definitions, attack rates were significantly higher in children under 16 years than adults (25.4% and 42.4% compared to 7.6% and 17.2%). The median time between symptom onset in the primary case and the secondary case was estimated at 3.0 days. CONCLUSIONS: Secondary attack rates for pandemic influenza A (H1N1) were comparable to seasonal influenza estimates suggesting similarities in transmission. High secondary attack rates in children provide additional support for increased susceptibility to infection.

Finding the gaps: an assessment of infection control surveillance needs in British Columbia acute care facilities.

BACKGROUND: This paper reports on an infection prevention and control surveillance survey of acute care facilities (ACFs) performed by the Provincial Infection Control Network of British Columbia. METHODS: A surveillance questionnaire was sent to all health care facilities that had access to an infection control professional. The questionnaire incorporated questions on organism-specific, disease-specific, and general surveillance activities. RESULTS: Questionnaires were returned from 47 of 51 (92%) of the ACFs surveyed. Participation in surveillance of methicillin-resistant Staphylococcus aureus-, vancomycin-resistant Enterococci-, and Clostridium difficile-associated disease ranged from 97% to 100%, but surveillance methodologies were inconsistent. Surgical-site infection surveillance did not correlate with the most commonly performed operations or with those procedures associated with higher morbidity and mortality from a postoperative infection. Considerable variation in data collection methods and case definitions was also identified. Surveillance for urinary tract infections, bloodstream infections, and ventilator-associated pneumonia was present in 28%, 51%, and 23% of responding ACFs, respectively. CONCLUSION: The current lack of a standardized surveillance system in British Columbia limits the ability of facilities to set appropriate benchmarks to assist in prioritizing and applying infection control interventions. The survey, however, has assisted in prioritizing implementation of surveillance activities and identifying the resources that would be required.

Infection control and antimicrobial restriction practices for antimicrobial-resistant organisms in Canadian tertiary care hospitals.

In 2003, a survey examining infection control and antimicrobial restriction policies and practices for preventing the emergence and transmission of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococci (VRE), and extended spectrum beta-lactamase (ESBL) was performed within Canadian teaching hospitals as part of the Canadian Nosocomial Infection Surveillance Program. Twenty-eight of 29 questionnaires were returned. The majority of facilities conducted admission screening for MRSA (96.4%) and VRE (89.3%) but only 1 site screened for ESBL/AmpC. Rates of MRSA, VRE, and ESBL remain low in Canada. It is believed that these lower rates may be due to intense admission screening protocols and stringent infection control policies for antimicrobial-resistant organisms (AROs) within Canadian institutions. Few (MRSA: 14.8%; VRE: 12.0%) recorded the number of patients screened. Regular prevalence surveys were done for MRSA (21.4%), VRE (35.7%), and ESBL/AmpC (3.8%). Pre-emptive precautions were applied for MRSA by 60.7% and for VRE by 75.0% of facilities. All facilities flagged patients previously identified with MRSA and VRE but only 46.2% flagged ESBL and 15.4% flagged AmpC patients. Barrier precautions varied by ARO and patient-care setting. In the inpatient non-ICU setting, more than 90% wore gowns and gloves for MRSA and VRE but only 50% for ESBL; and 57.1% wore masks for MRSA. Attempts to decolonize MRSA patients had been made by 82.1%, largely in order to place them in another facility. Policies restricting antimicrobial prescribing were reported by 21 facilities (75.0%). Further studies examining hospital infection control policies and corresponding rates of ARO infections would help in identifying and refining best practice guidelines within Canadian institutions.

Outbreak of acupuncture-associated cutaneous Mycobacterium abscessus infections.

BACKGROUND: Cutaneous atypical mycobacterial infections have been increasingly described in association with cosmetic and alternative procedures. OBJECTIVE: We report an outbreak of acupuncture-associated mycobacteriosis. Between April and December 2002, 32 patients developed cutaneous mycobacteriosis after visiting an acupuncture practice in Toronto, Canada. RESULTS: Of 23 patients whose lesions were biopsied, 6 (26.1%) had culture-confirmed infection with Mycobacterium abscessus. These isolates were genetically indistinguishable by amplified fragment length polymorphism. The median incubation period was 1 month. Of 24 patients for whom clinical information was available, 23 (95.8%) had resolution of their infection. All patients developed residual scarring or hyperpigmentation. CONCLUSION: Nontuberculous mycobacteria should be recognized as an emerging, but preventable, cause of acupuncture-associated infections.

West Nile Virus: the buzz on Ottawa residents' awareness, attitudes and practices.

BACKGROUND: In 2002, the City of Ottawa was interested in the public perception of West Nile Virus (WNV) and mosquito control. Their objectives were to assess: awareness of WNV, practices to reduce mosquito sources, personal protective measures, and attitudes towards community-based insecticide programs. METHODS: In July 2002, we administered a telephone survey to a random, stratified sample of urban, suburban and rural Ottawa households. RESULTS: Surveys were completed for 491 households. Most (77.2%) respondents reported they had heard of WNV, and of these, 58.3% reported WNV was an important health issue. Mosquito repellent was the most common personal protective measure, reported among 72.5% of respondents, of whom 76.9% used DEET products. Multivariate regression analyses showed that age was a significant predictor of repellent use, with respondents aged less than 51 years more likely to use repellent than older respondents (ORadj =2.0; 95% CI: 1.2-2.3). This age group was also more likely to use at least one personal protective behaviour (ORadj = 2.5; 95% CI: 1.4-4.5). Of 315 people selecting a justified time to larvicide, 4.8% chose "larvicides should never be used in Ottawa"; 33.4% stated that larviciding would be appropriate "when WNV was detected in birds or mosquitoes"; one third "needed more information" on the health and environmental effects of insecticides, prior to selecting a response. CONCLUSIONS: Our findings highlight the need for public education reinforcing WNV importance, emphasizing the health and environmental effects of insecticides as well as appropriate personal protective behaviours. Such messages should target older and urban residents.

Investigation of a nosocomial outbreak of severe acute respiratory syndrome (SARS) in Toronto, Canada.

BACKGROUND: Severe acute respiratory syndrome (SARS) was introduced into Canada by a visitor to Hong Kong who returned to Toronto on Feb. 23, 2003. Transmission to a family member who was later admitted to a community hospital in Toronto led to a large nosocomial outbreak. In this report we summarize the preliminary results of the epidemiological investigation into the transmission of SARS between 128 cases associated with this hospital outbreak. METHODS: We collected epidemiologic data on 128 probable and suspect cases of SARS associated with the hospital outbreak, including those who became infected in hospital and the next generation of illness arising among their contacts. Incubation periods were calculated based on cases with a single known exposure. Transmission chains from the index family to hospital contacts and within the hospital were mapped. Attack rates were calculated for nurses in 3 hospital wards where transmission occurred. RESULTS: The cases ranged in age from 21 months to 86 years; 60.2% were female. Seventeen deaths were reported (case-fatality rate 13.3%). Of the identified cases, 36.7% were hospital staff. Other cases were household or social contacts of SARS cases (29.6%), hospital patients (14.1%), visitors (14.1%) or other health care workers (5.5%). Of the 128 cases, 120 (93.8%) had documented contact with a SARS case or with a ward where there was a known SARS case. The remaining 8 cases without documented exposure are believed to have had exposure to an unidentified case and remain under investigation. The attack rates among nurses who worked in the emergency department, intensive care unit and coronary care unit ranged from 10.3% to 60.0%. Based on 42 of the 128 cases with a single known contact with a SARS case, the mean incubation period was 5 days (range 2 to 10 days). INTERPRETATION: Evidence to date suggests that SARS is a severe respiratory illness spread mainly by respiratory droplets. There has been no evidence of further transmission within the hospital after the elapse of 2 full incubation periods (20 days).