Dengue Endemicity, Force of Infection, and Variation in Transmission Intensity in 13 Endemic Countries.

Dengue endemicity varies but comparative, multicountry data are extremely limited. An improved understanding is needed to prioritize prevention, including vaccination, which is currently recommended only under specific epidemiological conditions. We used serological study data from 46 geographical sites in 13 countries to estimate dengue force of infection (FOI, the proportion of children seroconverting per year) under assumptions of either age-constant or age-varying FOI, and the age at which 50% and 80% of children had been infected. After exclusions, 13 661 subjects were included. Estimated constant FOI varied widely, from 1.7% (Singapore) to 24.1% (the Philippines). In the site-level analysis 44 sites (96%) reached 50% seroconversion and 35 sites (75%) reached 80% seroconversion by age 18 years, with significant heterogeneity. These findings confirm that children living in dengue-endemic countries receive intense early dengue exposure, increasing risk of secondary infection, and imply serosurveys at fine spatial resolutions are needed to inform vaccination campaigns.

Immunity certification for COVID-19: ethical considerations.

Restrictive measures imposed because of the coronavirus disease 2019 (COVID-19) pandemic have resulted in severe social, economic and health effects. Some countries have considered the use of immunity certification as a strategy to relax these measures for people who have recovered from the infection by issuing these individuals a document, commonly called an immunity passport. This document certifies them as having protective immunity against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus that causes COVID-19. The World Health Organization has advised against the implementation of immunity certification at present because of uncertainty about whether long-term immunity truly exists for those who have recovered from COVID-19 and concerns over the reliability of the proposed serological test method for determining immunity. Immunity certification can only be considered if scientific thresholds for assuring immunity are met, whether based on antibodies or other criteria. However, even if immunity certification became well supported by science, it has many ethical issues in terms of different restrictions on individual liberties and its implementation process. We examine the main considerations for the ethical acceptability of immunity certification to exempt individuals from restrictive measures during the COVID-19 pandemic. As well as needing to meet robust scientific criteria, the ethical acceptability of immunity certification depends on its uses and policy objectives and the measures in place to reduce potential harms, and prevent disproportionate burdens on non-certified individuals and violation of individual liberties and rights.

Les restrictions imposées dans le cadre de la lutte contre la pandémie de maladie à coronavirus 2019 (COVID-19) ont eu de lourdes conséquences économiques, sociales et sanitaires. Certains pays ont envisagé la mise en place d'une stratégie visant à alléger ces restrictions pour les individus guéris en leur octroyant un document communément appelé «passeport d'immunité¼. Ce document atteste qu'ils ont développé une immunité protectrice contre le coronavirus 2 du syndrome respiratoire aigu sévère (SARS-CoV-2), le virus à l'origine de la COVID-19. L'Organisation mondiale de la Santé a déconseillé l'usage du certificat d'immunité pour l'instant, car l'incertitude demeure quant à l'existence réelle d'une immunité à long terme pour ceux qui se sont remis de la COVID-19. En outre, la fiabilité des tests sérologiques censés déterminer si l'individu est immunisé n'est pas avérée. Un tel certificat ne peut être instauré que si les seuils scientifiques en matière d'immunité sont respectés, qu'ils soient fondés sur les anticorps ou sur d'autres critères. Néanmoins, même si le certificat d'immunité est désormais bien accepté par la science, il s'accompagne de nombreuses questions d'ordre éthique en ce qui concerne la limitation des libertés individuelles et la mise en œuvre. Dans le présent document, nous examinons les principales considérations à prendre en compte pour garantir l'acceptabilité éthique du certificat d'immunité visant à lever les mesures de restriction pour certaines personnes durant la pandémie de COVID-19. Cette acceptabilité éthique dépend non seulement de son degré de conformité à des critères scientifiques stricts, mais aussi de son usage, des objectifs politiques ainsi que des mesures mises en place pour atténuer les préjudices potentiels et éviter d'imposer une charge disproportionnée sur les individus dépourvus de certificat, ou de bafouer les droits et libertés de tout un chacun.

Las medidas restrictivas impuestas a causa de la pandemia de la enfermedad coronavirus de 2019 (COVID-19) han tenido graves efectos sociales, económicos y sanitarios. Algunos países han considerado la posibilidad de utilizar la certificación de inmunidad como estrategia para flexibilizar dichas medidas para las personas que se han recuperado de la infección mediante la expedición a dichas personas de un documento, comúnmente denominado pasaporte de inmunidad. Este documento certifica que han desarrollado inmunidad protectora contra el coronavirus-2 del síndrome respiratorio agudo severo (SARS-CoV-2), el virus que causa la COVID-19. La Organización Mundial de la Salud ha desaconsejado la aplicación de la certificación de la inmunidad en la actualidad debido a la incertidumbre sobre si existe realmente una inmunidad a largo plazo para quienes se han recuperado de la COVID-19 y a las preocupaciones sobre la fiabilidad del método de prueba serológica propuesto para determinar la inmunidad. La certificación de la inmunidad solo puede considerarse si se cumplen los umbrales científicos para asegurar la inmunidad, ya sea que se basen en anticuerpos o en otros criterios. Sin embargo, incluso si la certificación de la inmunidad llegara a estar bien respaldada por la ciencia, tiene muchas cuestiones éticas en cuanto a las diferentes restricciones de las libertades individuales y su proceso de aplicación. Examinamos las principales consideraciones sobre la aceptabilidad ética de la certificación de la inmunidad para eximir a los individuos de las medidas restrictivas durante la pandemia de la COVID-19. Además de necesitar cumplir criterios científicos sólidos, la aceptabilidad ética de la certificación de inmunidad depende de sus usos y objetivos de política y de las medidas que se apliquen para reducir los posibles daños y evitar que se impongan cargas desproporcionadas a las personas que no cuenten con dicha certificación y se violen las libertades y derechos individuales.

Ethical Implementation of Immunity Passports During the COVID-19 Pandemic.

A number of countries are planning the use of "immunity passports" as a way to ease restrictive measures and allow infected and recovered people to return to work during the COVID-19 pandemic. This paper brings together key scientific uncertainties regarding the use of serological tests to assure immune status and a public health ethics perspective to inform key considerations in the ethical implementation of immunity passport policies. Ill-conceived policies have the potential to cause severe unintended harms that could result in greater inequity, the stigmatization of certain sectors of society, and heightened risks and unequal treatment of individuals due to erroneous test results. Immunity passports could, however, be used to achieve collective benefits and benefits for specific populations besides facilitating economic recovery. We conclude that sector-based policies that prioritize access to testing based on societal need are likely to be fairer and logistically more feasible, while minimizing stigma and reducing incentives for fraud. Clear guidelines need to be set out for which sectors of society should be prioritized for testing, and rigorous mechanisms should be in place to validate test results and identify cases of reinfection.

Burden and Cost of Hospitalization for Respiratory Syncytial Virus in Young Children, Singapore.

Respiratory syncytial virus (RSV) is the most common cause of pediatric acute lower respiratory tract infection worldwide. Detailed data on the health and economic burden of RSV disease are lacking from tropical settings with year-round RSV transmission. We developed a statistical and economic model to estimate the annual incidence and healthcare cost of medically attended RSV disease among young children in Singapore, using Monte Carlo simulation to account for uncertainty in model parameters. RSV accounted for 708 hospitalizations in children <6 months of age (33.5/1,000 child-years) and 1,096 in children 6-29 months of age (13.2/1,000 child-years). The cost of hospitalization was SGD 5.7 million (US $4.3 million) at 2014 prices; patients bore 60% of the cost. RSV-associated disease burden in tropical settings in Asia is high and comparable to other settings. Further work incorporating efficacy data from ongoing vaccine trials will help to determine the potential cost-effectiveness of different vaccination strategies.

Seroepidemiologic Study Designs for Determining SARS-COV-2 Transmission and Immunity.

Serologic studies are crucial for clarifying dynamics of the coronavirus disease pandemic. Past work on serologic studies (e.g., during influenza pandemics) has made relevant contributions, but specific conditions of the current situation require adaptation. Although detection of antibodies to measure exposure, immunity, or both seems straightforward conceptually, numerous challenges exist in terms of sample collection, what the presence of antibodies actually means, and appropriate analysis and interpretation to account for test accuracy and sampling biases. Successful deployment of serologic studies depends on type and performance of serologic tests, population studied, use of adequate study designs, and appropriate analysis and interpretation of data. We highlight key questions that serologic studies can help answer at different times, review strengths and limitations of different assay types and study designs, and discuss methods for rapid sharing and analysis of serologic data to determine global transmission of severe acute respiratory syndrome coronavirus 2.

Impact of national interventions to promote responsible antibiotic use: a systematic review.

BACKGROUND: Global recognition of antimicrobial resistance (AMR) as an urgent public health problem has galvanized national and international efforts. Chief among these are interventions to curb the overuse and misuse of antibiotics. However, the impact of these initiatives is not fully understood, making it difficult to assess the expected effectiveness and sustainability of further policy interventions. We conducted a systematic review to summarize existing evidence for the impact of nationally enforced interventions to reduce inappropriate antibiotic use in humans. METHODS: We searched seven databases and examined reference lists of retrieved articles. To be included, articles had to evaluate the impact of national responsible use initiatives. We excluded studies that only described policy implementations. RESULTS: We identified 34 articles detailing interventions in 21 high- and upper-middle-income countries. Interventions addressing inappropriate antibiotic access included antibiotic committees, clinical guidelines and prescribing restrictions. There was consistent evidence that these were effective at reducing antibiotic consumption and prescription. Interventions targeting inappropriate antibiotic demand consisted of education campaigns for healthcare professionals and the general public. Evidence for this was mixed, with several studies showing no impact on overall antibiotic consumption. CONCLUSIONS: National-level interventions to reduce inappropriate access to antibiotics can be effective. However, evidence is limited to high- and upper-middle-income countries, and more evidence is needed on the long-term sustained impact of interventions. There should also be a simultaneous push towards standardized outcome measures to enable comparisons of interventions in different settings.

Estimated dengue force of infection and burden of primary infections among Indian children.

BACKGROUND: Comprehensive, age-stratified dengue surveillance data are unavailable from India and many more dengue cases occur than are reported. Additional information on dengue transmission dynamics can inform understanding of disease endemicity and infection risk. METHODS: Using age-stratified dengue IgG seroprevalence data from 2556 Indian children aged 5-10 years, we estimated annual force of infection (FOI) at each of 6 sites using a binomial regression model. We estimated the ages by which 50 and 70% of children were first infected; and predicted seroprevalence in children aged 1-10 years assuming constant force-of-infection. Applying these infection rates to national census data, we then calculated the number of primary dengue infections occurring, annually, in Indian children. RESULTS: Annual force-of-infection at all sites combined was 11.9% (95% CI 8.8-16.2), varying across sites from 3.5% (95% CI 2.8-4.4) to 21.2% (95% CI 18.4-24.5). Overall, 50 and 70% of children were infected by 5.8 (95% CI 4.3-7.9) and 10.1 (95% CI 7.4-13.7) years respectively. In all sites except Kalyani, > 70% of children had been infected before their 11th birthday, and goodness-of-fit statistics indicated a relatively constant force-of-infection over time except at two sites (Wardha and Hyderabad). Nationwide, we estimated 17,013,527 children (95% CI: 14,518,438- 19,218,733), equivalent to 6.5% of children aged < 11 years, experience their first infection annually. CONCLUSIONS: Dengue force-of-infection in India is comparable to other highly endemic countries. Significant variation across sites exists, likely reflecting local epidemiological variation. The number of annual primary infections is indicative of a significant, under-reported burden of secondary infections and symptomatic episodes. TRIAL REGISTRATION: Registered retrospectively with clinicaltrials.gov ( NCT01477671 ; 18/11/2011) and clinical trials registry of India (ctri.nic.in; CTRI/2011/12/002243 ; 15/12/2011). Date of enrollment of 1st subject: 22/9/2011.

Coverage and determinants of influenza vaccine among pregnant women: a cross-sectional study.

BACKGROUND: Pregnant women are at increased risk of influenza-related complications. The World Health Organisation recommends influenza vaccination to this high-risk population as highest priority. However, achieving high influenza vaccine coverage among pregnant women remains challenging. We conducted a cross-sectional survey to estimate the coverage and determinants of influenza vaccination among pregnant women in Singapore. METHODS: Between September and November 2017, pregnant women aged ≥21 years were recruited at two public hospitals in Singapore. Participants completed an anonymous, self-administered online questionnaire assessing participants' influenza vaccination uptake, knowledge of and attitudes towards influenza and the influenza vaccine, vaccination history, willingness to pay for the influenza vaccine, and external cues to vaccination. We estimated vaccine coverage and used multivariable Poisson models to identify factors associated with vaccine uptake. RESULTS: Response rate was 61% (500/814). Only 49 women (9.8, 95% Confidence Interval (CI): 7.3-12.7%) reported receiving the vaccine during their current pregnancy. A few misconceptions were identified among participants, such as the belief that influenza can be treated with antibiotics. The most frequent reason for not being vaccinated was lack of recommendation. Women who were personally advised to get vaccinated against influenza during pregnancy were 7 times more likely to be vaccinated (prevalence ratio (PR) = 7.11; 95% CI: 3.92-12.90). However, only 12% of women were personally advised to get vaccinated. Other factors associated with vaccine uptake were vaccination during a previous pregnancy (PR = 2.51; 95% CI: 1.54-4.11), having insurance to cover the cost of the vaccine (PR = 2.32; 95% CI: 1.43-3.76), and higher vaccine confidence (PR = 1.62; 95% CI: 1.30-2.01). CONCLUSIONS: Influenza vaccination uptake among pregnant women in Singapore is low. There is considerable scope for improving vaccination coverage in this high-risk population through vaccination recommendations from healthcare professionals, and public communication targeting common misconceptions about influenza and influenza vaccines.

Association between semi-quantitative microbial load and respiratory symptoms among Thai military recruits: a prospective cohort study.

BACKGROUND: Multiplex real-time polymerase chain reaction assays have improved diagnostic sensitivity for a wide range of pathogens. However, co-detection of multiple agents and bacterial colonization make it difficult to distinguish between asymptomatic infection or illness aetiology. We assessed whether semi-quantitative microbial load data can differentiate between symptomatic and asymptomatic states for common respiratory pathogens. METHODS: We obtained throat and nasal swab samples from military trainees at two Thai Army barracks. Specimens were collected at the start and end of 10-week training periods (non-acute samples), and from individuals who developed upper respiratory tract infection during training (acute samples). We analysed the samples using a commercial multiplex respiratory panel comprising 33 bacterial, viral and fungal targets. We used random effects tobit models to compare cycle threshold (Ct) value distributions from non-acute and acute samples. RESULTS: We analysed 341 non-acute and 145 acute swab samples from 274 participants. Haemophilus influenzae type B was the most commonly detected microbe (77.4% of non-acute and 64.8% of acute samples). In acute samples, nine specific microbe pairs were detected more frequently than expected by chance. Regression models indicated significantly lower microbial load in non-acute relative to acute samples for H. influenzae non-type B, Streptococcus pneumoniae and rhinovirus, although it was not possible to identify a Ct-value threshold indicating causal etiology for any of these organisms. CONCLUSIONS: Semi-quantitative measures of microbial concentration did not reliably differentiate between illness and asymptomatic colonization, suggesting that clinical symptoms may not always be directly related to microbial load for common respiratory infections.

Estimating the Burden of Medically Attended Norovirus Gastroenteritis: Modeling Linked Primary Care and Hospitalization Datasets.

Background: Norovirus is the leading cause of community-acquired and nosocomial acute gastroenteritis. Routine testing for norovirus is seldom undertaken, and diagnosis is mainly based on presenting symptoms. This makes understanding the burden of medically attended norovirus-attributable gastroenteritis (MA-NGE) and targeting care and prevention strategies challenging. Methods: We used linked population-based healthcare datasets (Clinical Practice Research Datalink General Practice OnLine Database linked with Hospital Episode Statistics Admitted Patient Care) to model the incidence of MA-NGE associated with primary care consultations or hospitalizations according to age groups in England in the period July 2007-June 2013. Results: Mean annual incidence rates of MA-NGE were 4.9/1000 person-years and 0.7/1000 person-years for episodes involving primary care or hospitalizations, respectively. Incidence rates were highest in children aged <5 years: 34.0 consultations/1000 person-years and 3.3 hospitalizations/1000 person-years. Medically attended norovirus-attributable gastroenteritis hospitalization rates were second highest in adults aged >65 years (1.7/1000 person-years). Conclusions: In this particular study, the burden of MA-NGE estimated from healthcare datasets was higher than previously estimated in small cohort studies in England. Routinely collected primary care and hospitalization datasets are useful resources to estimate and monitor the burden of MA-NGE in a population over time.

Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis quantified the protective effect of facemasks and respirators against respiratory infections among healthcare workers. Relevant articles were retrieved from Pubmed, EMBASE, and Web of Science. Meta-analyses were conducted to calculate pooled estimates. Meta-analysis of randomized controlled trials (RCTs) indicated a protective effect of masks and respirators against clinical respiratory illness (CRI) (risk ratio [RR] = 0.59; 95% confidence interval [CI]:0.46-0.77) and influenza-like illness (ILI) (RR = 0.34; 95% CI:0.14-0.82). Compared to masks, N95 respirators conferred superior protection against CRI (RR = 0.47; 95% CI: 0.36-0.62) and laboratory-confirmed bacterial (RR = 0.46; 95% CI: 0.34-0.62), but not viral infections or ILI. Meta-analysis of observational studies provided evidence of a protective effect of masks (OR = 0.13; 95% CI: 0.03-0.62) and respirators (OR = 0.12; 95% CI: 0.06-0.26) against severe acute respiratory syndrome (SARS). This systematic review and meta-analysis supports the use of respiratory protection. However, the existing evidence is sparse and findings are inconsistent within and across studies. Multicentre RCTs with standardized protocols conducted outside epidemic periods would help to clarify the circumstances under which the use of masks or respirators is most warranted.

The epidemiology and transmission of methicillin-resistant Staphylococcus aureus in the community in Singapore: study protocol for a longitudinal household study.

BACKGROUND/AIM: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common multidrug-resistant organisms in healthcare settings worldwide, but little is known about MRSA transmission outside of acute healthcare settings especially in Asia. We describe the methods for a prospective longitudinal study of MRSA prevalence and transmission. METHODS: MRSA-colonized individuals were identified from MRSA admission screening at two tertiary hospitals and recruited together with their household contacts. Participants submitted self-collected nasal, axilla and groin (NAG) swabs by mail for MRSA culture at baseline and monthly thereafter for 6 months. A comparison group of households of MRSA-negative patients provided swab samples at one time point. In a validation sub-study, separate swabs from each site were collected from randomly selected individuals, to compare MRSA detection rates between swab sites, and between samples collected by participants versus those collected by trained research staff. Information on each participant's demographic information, medical status and medical history, past healthcare facilities usage and contacts, and personal interactions with others were collected using a self-administered questionnaire. DISCUSSION/CONCLUSION: Understanding the dynamics of MRSA persistence and transmission in the community is crucial to devising and evaluating successful MRSA control strategies. Close contact with MRSA colonized patients may to be important for MRSA persistence in the community; evidence from this study on the extent of community MRSA could inform the development of household- or community-based interventions to reduce MRSA colonization of close contacts and subsequent re-introduction of MRSA into healthcare settings. Analysis of longitudinal data using whole-genome sequencing will yield further information regarding MRSA transmission within households, with significant implications for MRSA infection control outside acute hospital settings.

Age-Specific Incidence Rates for Norovirus in the Community and Presenting to Primary Healthcare Facilities in the United Kingdom.

In a prospective, population-based cohort study and a study of primary-healthcare consultations, we had a rare opportunity to estimate age-specific rates of norovirus-associated infectious intestinal disease in the United Kingdom. Rates in children aged <5 years were significantly higher than those for other age groups in the community (142.6 cases per 1000 person-years [95% confidence interval {CI}, 99.8-203.9] vs 37.6 [95% CI, 31.5-44.7]) and those for individuals presenting to primary healthcare (14.4 cases per 1000 person-years [95% CI, 8.5-24.5] vs 1.4 [95% CI, .9-2.0]). Robust incidence estimates are crucial for vaccination policy makers. This study emphasises the impact of norovirus-associated infectious intestinal disease, especially in children aged <5 years.

Characteristics of acute febrile illness and determinants of illness recovery among adults presenting to Singapore primary care clinics.

BACKGROUND: Undifferentiated acute febrile illness (AFI) is a common presentation among adults in primary care settings in Singapore but large gaps exist in the understanding of the characteristics of these patients. We studied clinical and epidemiological characteristics of AFI patients and factors associated with delayed recovery from AFI. METHODS: We performed a secondary data analysis using data from the Early DENgue infection and outcome (EDEN) study on 2046 adult patients presenting at 5 Singapore polyclinics between December 2007 and February 2013 with a history of fever (≥38 °C) for less than 72 h. We used an accelerated failure time model to investigate factors associated with delayed recovery from AFI. RESULTS: The mean age of patients was 36.6 years, 65 % were male, 51 % were of Chinese ethnicity, and 75 % lived in public housing. Median illness duration was 5 days (interquartile range, 3-7). In multivariable analysis, the unemployed and white collar workers had longer illness duration compared with blue collar workers (time ratio (TR), 1.10; 95 % confidence interval (CI), 1.03-1.17 and TR, 1.08; 95 % CI, 1.02-1.15, respectively). Patients with more symptoms at initial consultation had slower recovery (TR, 1.03 per additional symptom; 95 % CI, 1.02-1.03). Other clinical factors were also associated with longer duration of illness, including use of analgesics (TR, 1.21; 95 % CI, 1.15-1.28); use of cough medicines (TR, 1.14; 95 % CI, 1.08-1.20); use of antibiotics (TR, 1.14; 95 % CI, 1.07-1.21); and hospitalization (TR, 1.59; 95 % CI, 1.39-1.82). Compared to patients with normal WBC count at first consultation, those with low WBC count had slower recovery (TR, 1.14; 95 % CI, 1.07-1.21), while the reverse was observed among patients with high WBC count (TR, 0.94; 95 % CI, 0.88-1.00). CONCLUSIONS: Differences in illness duration among different types of employment may reflect differences in their underlying general health status. Early identification of factors delaying recovery could help triage management in a primary care setting. In-depth characterization of fever etiology in Singapore will improve surveillance and control activities.

Diarrheagenic pathogens in adults attending a hospital in Singapore.

BACKGROUND: Singapore's diarrhoeal notification system is based on specific pathogens. Official data may thus be skewed towards notifiable diseases. Limited information is available on the profiles of aetiological agents responsible for acute gastroenteritis (AGE) cases, especially among the adult population. To understand the frequency and distribution of potential causative agents of diarrheal disease in Singapore, we screened adults' stool samples collected from a large public hospital. METHODS: The stool samples were screened for 18 diarrheagenic pathogens using a combination of commercial multiplex polymerase chain reaction (PCR), in-house singleplex PCR and immunochromatographic assays. One hundred adult faecal samples that were collected from October 2013 to January 2014 for routine diagnostic purposes and submitted for culture at Tan Tock Seng Hospital, Singapore were used. RESULTS: Pathogens were detected in 32% of the samples. The predominant organisms encountered were norovirus genogroup II (11%), Aeromonas spp. (9%) and Campylobacter spp. (5%). One sample was positive for both verocytotoxigenic E. coli (VTEC) and E. coli O157:H7. Two other samples were positive for VTEC only, and one other sample was positive for E. coli O157:H7 only. Astrovirus, C. perfringens, Shigella spp. and toxigenic C. difficile were each detected in 2% of the samples. Cryptosporidium parvum, Giardia lamblia, group A rotavirus, Salmonella spp. and Vibrio spp. were each detected in 1% of the samples. No L. monocytogenes, Y. enterocolitica, enteric adenovirus, or norovirus genogroup I were detected. CONCLUSION: Our preliminary findings suggest that pathogens causing non-notifiable diseases might have contributed considerably to the adult hospitalised AGE cases. However, as the samples were from an adult hospital, the data obtained may not be representative of the whole community. Thus, a larger study to collect clinical samples and risk exposure data from primary healthcare clinics and children hospital is planned for, to gain a more holistic perspective on the epidemiology of AGE in Singapore. A larger study may also offer valuable insights for improving the approach of microbiological surveillance of food, as well as strategizing inspection efforts along the food supply chain by public health authorities.

Estimating public health risks of infectious disease events: A Canadian approach to rapid risk assessment.

Background: The COVID-19 pandemic highlighted the need for timely, evidence-based rapid risk assessments (RRA) of infectious disease events to inform public health action during rapidly evolving situations with high uncertainty. In 2022, the Public Health Agency of Canada established a coordinated approach to public health risk assessment, including a methodology for qualitative RRA of infectious disease threats. Objective: To describe the RRA methodology and illustrate its use with examples from different infectious hazards of public health concern. Methods: The RRA methodology employs the risk pathway to describe the sequence of events leading from a hazard's source to the adverse event of concern and subsequent impacts; define specific questions to be addressed; and identify relevant knowledge gaps, limitations and recommendations. Qualitative likelihood and impact estimates are derived through integration of evidence review and expert opinion and are communicated together with corresponding levels of uncertainty. The impacts of the event are based on an assessment of the most likely spread scenario within Canada, considering individual-level impact on affected individuals, the impact on the general population and, if relevant, sub-groups at higher risk. Results: This RRA approach aligns with well-established international methods and provides flexibility to accommodate a broad range of risk questions. It has been implemented to estimate the risk of various threats of concern to Canada, including mpox, avian influenza A(H5N1) and measles. Conclusion: Given the broad range and complexity of public health hazards, RRAs provide a timely, coordinated and systematic process for characterizing and communicating the risk to inform risk mitigation and decision-making and to guide appropriate public health response.

Characterization of water and wildlife strains as a subgroup of Campylobacter jejuni using DNA microarrays.

Campylobacter jejuni is the leading cause of human bacterial gastroenteritis worldwide, but source attribution of the organism is difficult. Previously, DNA microarrays were used to investigate isolate source, which suggested a non-livestock source of infection. In this study we analysed the genome content of 162 clinical, livestock and water and wildlife (WW) associated isolates combined with the previous study. Isolates were grouped by genotypes into nine clusters (C1 to C9). Multilocus sequence typing (MLST) data demonstrated that livestock associated clonal complexes dominated clusters C1-C6. The majority of WW isolates were present in the C9 cluster. Analysis of previously reported genomic variable regions demonstrated that these regions were linked to specific clusters. Two novel variable regions were identified. A six gene multiplex PCR (mPCR) assay, designed to effectively differentiated strains into clusters, was validated with 30 isolates. A further five WW isolates were tested by mPCR and were assigned to the C7-C9 group of clusters. The predictive mPCR test could be used to indicate if a clinical case has come from domesticated or WW sources. Our findings provide further evidence that WW C. jejuni subtypes show niche adaptation and may be important in causing human infection.

The second study of infectious intestinal disease (IID2): increased rates of recurrent diarrhoea in individuals aged 65 years and above.

BACKGROUND: Infectious intestinal disease (IID) is a major health and economic burden in high-income countries. In the UK, there are an estimated 17 million IID cases annually, of which 6 million are caused by the 12 most common pathogens. Host factors that influence risk of IID are not well understood. METHODS: We analyzed data from the IID2 Study, a UK cohort that measured IID incidence, to investigate factors associated with recurrent IID. We calculated rates of IID by age group, sex, previous episodes experienced, and socioecomic indicators. We used Cox models to investigate factors associated with recurrent illness. RESULTS: The rate of IID was five times higher among infants than those aged 65 years and above (hazard ratio, HR = 5.0, 95% CI: 3.1 - 8.0). However, the association between previous IID and a subsequent IID episode was stronger in the elderly. Among those aged 65 years and above, each additional IID episode increased the rate of subsequent IID three-fold (HR = 3.1, 95% CI: 2.5 - 3.7). Among infants, the corresponding increase was 1.7-fold (HR = 1.7, 95% CI: 1.3 - 2.3). CONCLUSIONS: Elderly populations have a high propensity for recurrent IID. More detailed studies are needed to identify vulnerable subgroups and susceptibility factors, and inform adequate control policies among the elderly.

Longitudinal study of infectious intestinal disease in the UK (IID2 study): incidence in the community and presenting to general practice.

OBJECTIVES: To estimate, overall and by organism, the incidence of infectious intestinal disease (IID) in the community, presenting to general practice (GP) and reported to national surveillance. DESIGN: Prospective, community cohort study and prospective study of GP presentation conducted between April 2008 and August 2009. SETTING: Eighty-eight GPs across the UK recruited from the Medical Research Council General Practice Research Framework and the Primary Care Research Networks. PARTICIPANTS: 6836 participants registered with the 88 participating practices in the community study; 991 patients with UK-acquired IID presenting to one of 37 practices taking part in the GP presentation study. MAIN OUTCOME MEASURES: IID rates in the community, presenting to GP and reported to national surveillance, overall and by organism; annual IID cases and GP consultations by organism. RESULTS: The overall rate of IID in the community was 274 cases per 1000 person-years (95% CI 254 to 296); the rate of GP consultations was 17.7 per 1000 person-years (95% CI 14.4 to 21.8). There were 147 community cases and 10 GP consultations for every case reported to national surveillance. Norovirus was the most common organism, with incidence rates of 47 community cases per 1000 person-years and 2.1 GP consultations per 1000 person-years. Campylobacter was the most common bacterial pathogen, with a rate of 9.3 cases per 1000 person-years in the community, and 1.3 GP consultations per 1000 person-years. We estimate that there are up to 17 million sporadic, community cases of IID and 1 million GP consultations annually in the UK. Of these, norovirus accounts for 3 million cases and 130,000 GP consultations, and Campylobacter is responsible for 500,000 cases and 80,000 GP consultations. CONCLUSIONS: IID poses a substantial community and healthcare burden in the UK. Control efforts must focus particularly on reducing the burden due to Campylobacter and enteric viruses.