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Background: Previous research has identified the impacts of legal frameworks that criminalize HIV non-disclosure among people living with HIV (e.g., elevated stigma and violence). However, far less is known about the perspectives or experiences of people–particularly, men–who are HIV-seronegative or who are unaware of their status. The objective of this paper is to describe the health and social risks that young men perceive to be associated with an HIV diagnosis in the context of Canada’s current legal framework pertaining to HIV non-disclosure. Methods: We analyzed data from 100 in-depth interviews (2013–2016) conducted with 85 young men ages 18–30 in Vancouver on the topic of the criminalization of HIV non-disclosure. Results: Our analysis revealed two dominant narratives in relation to HIV criminalization: (a) interrogation and (b) justification. An interrogation narrative problematized the moral permissibility of criminalizing HIV non-disclosure. In this narrative, Canada’s HIV non-disclosure legal framework was characterized as creating unjust barriers to HIV testing uptake, as well as impeding access to and reducing retention in care for those living with HIV. Conversely, a justification narrative featured a surprising number of references to HIV as a “death sentence”, despite effective treatments being universally available in Canada. However, most of those who presented the justification narrative asserted that the criminalization of HIV non-disclosure was morally justified in light of the perceived negative stigma-related impacts of HIV (e.g., discrimination; being ostracized from sex or romantic partners, friends, family). The justification narrative often reflected a belief that the legal framework provides both punishment and deterrence, which were perceived to supersede any barriers to care for both HIV-positive and -negative individuals. Conclusion: Public education regarding contemporary medical advances in HIV may help contest lay understandings of HIV as a “death sentence”, which is particularly relevant to destabilizing justification narratives. However, significant strengthening of HIV stigma-reduction efforts will be needed to move society away from narratives that attempt to justify Canada’s current HIV non-disclosure legal framework. [ABSTRACT FROM AUTHOR]

While climate scientists have developed high resolution data sets on the distribution of climate risks, we still lack comparable data on the local distribution of public climate change opinions. This paper provides the first effort to estimate local climate and energy opinion variability outside the United States. Using a multi-level regression and post-stratification (MRP) approach, we estimate opinion in federal electoral districts and provinces. We demonstrate that a majority of the Canadian public consistently believes that climate change is happening. Belief in climate change’s causes varies geographically, with more people attributing it to human activity in urban as opposed to rural areas. Most prominently, we find majority support for carbon cap and trade policy in every province and district. By contrast, support for carbon taxation is more heterogeneous. Compared to the distribution of US climate opinions, Canadians believe climate change is happening at higher levels. This new opinion data set will support climate policy analysis and climate policy decision making at national, provincial and local levels. [ABSTRACT FROM AUTHOR]

With the advent of continuous antiretroviral therapy, HIV has become a complex chronic, rather than acute, condition. The Chronic Care Model (CCM) provides an integrated approach to the delivery of care for people with chronic conditions that could therefore be applied to the delivery of care for people living with HIV. Our objective was to assess the alignment of HIV care settings with the CCM. We conducted a mixed methods study to explore structures, organization and care processes of Canadian HIV care settings. The quantitative results of phase one are published elsewhere. For phase two, we conducted semi-structured interviews with key informants from 12 HIV care settings across Canada. Irrespective of composition of the care setting or its location, HIV care in Canada is well aligned with several components of the CCM, most prominently in the areas of linkage to community resources and delivery system design with inter-professional team-based care. We propose the need for improvements in the availability of electronic clinical information systems and self-management support services to support better care delivery and health outcomes among people living with HIV in Canada. [ABSTRACT FROM AUTHOR]

Introduction: La Maison Bleue is a community-based perinatal health and social centre in Montreal that provides services during pregnancy up to age five to families living in vulnerable contexts. The study aimed to describe: 1) the challenges and protective factors that affect the well-being of migrant families receiving care at La Maison Bleue; and 2) how La Maison Bleue strengthens resilience among these families. Methods: We conducted a focused ethnography. Immigrants, refugees, asylum seekers and undocumented migrants were invited to participate. We collected data from November to December 2017 via semi-structured interviews and participant observation during group activities at La Maison Bleue. Data were thematically analysed. Results: Twenty-four mothers participated (9 interviewed, 17 observed). Challenges to well-being included family separation, isolation, loss of support, the immigration process, an unfamiliar culture and environment, and language barriers. Key protective factors were women’s intrinsic drive to overcome difficulties, their positive outlook and ability to find meaning in their adversity, their faith, culture and traditions, and supportive relationships, both locally and transnationally. La Maison Bleue strengthened resilience by providing a safe space, offering holistic care that responded to both medical and psychosocial needs, and empowering women to achieve their full potential towards better health for themselves and their families. Conclusion: Migrant mothers have many strengths and centres like La Maison Bleue can offer a safe space and be an empowering community resource to assist mothers in overcoming the multiple challenges that they face while resettling and raising their young children in a new country. [ABSTRACT FROM AUTHOR]

Residential segregation into spatial neighborhoods and boroughs is a well-known spatial dynamic process that characterise complex urban environments. Existing models of segregation, including the pioneering Schelling ones, often do not consider all the factors that can contribute to this process. Segregation as well as aggregation emerges from local interactions among individuals, and is rooted in the complexity of social, economic and environmental interactions. The main objective of this study is to develop and implement a geospatial agent-based model to simulate the decision-making process of location of new household for incoming immigrant populations. Particularly this study aims to simulate and analyse the dynamics of the new immigrant populations arriving in the bilingual cities and boroughs of the island of Montreal. The model was implemented in NetLogo software, using real geospatial datasets. The obtained simulation results indicate realistic spatial patterns of spatial composition of the ethnographic fabric on the island of Montreal. The proposed model has the potential to be used as part of the city planning purposes. [ABSTRACT FROM AUTHOR]

Non-consensual condom removal (NCCR) is the removal of a condom before or during sexual intercourse without one’s partner's consent. Despite considerable news and media attention devoted to the trend (as stealthing), little empirical research to date has examined people’s views of the practice. The present study aimed to contribute toward generating empirical evidence to guide the discussion surrounding NCCR. We asked participants about whether or not they felt NCCR is wrong, whether there should be consequences for its perpetration, and contextualized responses within legal context. A total of 592 undergraduate students took part in an online survey inquiring about their experiences with and views of NCCR. We used descriptive statistics to determine sample prevalence and outcomes of NCCR and qualitatively analyzed responses to open-ended questions asking about perceptions of NCCR. Of participants who had engaged in penetrative sexual intercourse with a male partner using an external condom, 18.7%, 95% CI [14.4, 22.7] reported that they had NCCR perpetrated against them. The majority of these participants reported that they experienced NCCR negatively and encountered related consequences; several reported contracting an STI, experiencing an unplanned pregnancy, or both. Nearly all participants expressed that NCCR is wrong, citing reasons that included the lack of consent, possibility of unplanned or unwanted outcomes, and a betrayal of trust. In this study, we found that there was agreement that NCCR is wrong, but variability in responses regarding the circumstances under which there should be consequences for the action. These perceptions reflect the current uncertainty in law. We recommend researchers refer to the phenomenon as NCCR (rather than stealthing) and discuss related issues to encourage future research to adopt consistent and accurate labels and definitions for NCCR. We hope that our findings will guide future research and spur public and legal discussion on NCCR. [ABSTRACT FROM AUTHOR]

Objectives: The Healthy Kids Community Challenge is a large-scale, centrally-coordinated, community-based intervention in Ontario, Canada that promotes healthy behaviours towards improving healthy weights among children. With the goal of exploring tools available to evaluators, we leveraged electronic medical records from primary care physicians to assess child weights prior to launch of the Healthy Kids Community Challenge. This study compares the baseline (i.e. pre-intervention) prevalence of overweight and obesity in children 1–12 years of age living within and outside Healthy Kids Community Challenge communities. Design: Cross-sectional analysis of a primary care patient cohort. Setting: Electronic Medical Record Administrative data Linked Database (EMRALD) in Ontario, Canada. Participants: A cohort of 19 920 Ontario children who are rostered to an EMRALD physician. Children were 1–12 years of age at a primary care visit with recorded measured height and weight, between January 1, 2014 and December 31, 2015. Outcome measure: Overweight and obesity as determined by age- and sex-standardized body mass index using World Health Organization’s Growth Standards. Results: In Healthy Kids Community Challenge communities, 25.6% (95% CI 24.6–26.6%) of children had zBMI above normal (i.e. >1) compared to 26.7% (95% CI 25.9–27.5%) for children living outside of Healthy Kids Community Challenge communities. Conclusions: Despite some differences in sociodemographic characteristics, zBMI of children aged 1–12 years were similar inside and outside of Healthy Kids Community Challenge community boundaries prior to program launch. [ABSTRACT FROM AUTHOR]

Background: Population trends of disease prevalence and incidence over time measure burden of disease and inform healthcare planning. Neuromuscular disorders (NMD) affect muscle and nerve function with varying degrees of severity and disease progression. Objective: Using health administrative databases we described trends in incidence, prevalence, and mortality of adults and children with NMD. We also explored place of death and use of palliative care. Methods: Population-based (Ontario, Canada) cohort study (2003 to 2014) of adults and children with NMD identified using International Classification of Disease and health insurance billing codes within administrative health databases. Results: Adult disease prevalence increased on average per year by 8% (95% confidence interval (CI) 6% to 10%, P <.001), with the largest increase in adults18-39 years. Childhood disease prevalence increased by 10% (95% CI 8% to 11%, P <.0001) per year, with the largest increase in children 0 to 5 years. Prevalence increased across all diagnoses except amyotrophic lateral sclerosis and spinal muscular atrophy for adults and all diagnoses for children. Adult incidence decreased by 3% (95% CI -4% to -2%, P <.0001) but incidence remained stable in children. Death occurred in 34,336 (18.5%) adults; 21,236 (61.8%) of whom received palliative care. Death occurred in 1,009 (5.6%) children; 507 (50.2%) of whom received palliative care. Mortality decreased over time in adults (odds ratio (OR) 0.86, 95% CI 0.86–0.87, P <.0001) and children (OR 0.79, 95% CI 0.76–0.82, P <.0001). Use of palliative care over time increased for adults (OR 1.18, 95% CI 1.09 to 1.28, P <.0001) and children (OR 1.22, 95% CI 1.20 to 1.23, P <.0001). Conclusions: In both adults and children, NMD prevalence is rising and mortality rates are declining. In adults incidence is decreasing while in children it remains stable. This confirms on a population-based level the increased survival of children and adults with NMD. [ABSTRACT FROM AUTHOR]

Tree cavities provide a critical resource for cavity-nesting animals, and high quality cavities can be difficult for animals to acquire in habitats where competition is high. We investigated the breeding performance of Lewis's Woodpeckers in three habitat types in British Columbia, Canada in 2013 and 2014. We also assessed whether the number of nest competitors and cavity availability influenced the habitat specific breeding performance of this threatened cavity nesting species. We found that daily nest survival rate was lower in burned habitat (0.15 ± 0.08 (0.05–0.37)) than in live pine (0.72 ± 0.10 (0.51–0.87)) or cottonwood (0.69 ± 0.09 (0.51–0.83)) habitats. However, hatching success (the proportion of eggs that hatch) was lower in live pine habitat (0.59 ± 0.09 95% CI) than burned (0.77 ± 0.19 95% CI) or cottonwood (0.80 ± 0.07 95% CI) habitat, and the fledging success of successful nests in live pine and burned habitat (1.86 ± 0.31 and 1.88 ± 0.59 95% CI, respectively) was slightly lower than in cottonwood habitat (2.61 ± 0.45 95% CI). Consequently, Lewis's Woodpeckers in cottonwood habitat produced more fledglings per nesting attempt (2.05 ± 0.49 95% CI) than in live pine (1.53 ± 0.35 95% CI) or burned (0.79 ± 0.49 95% CI) habitat. Habitats differed in the number of nesting competitors and the number of suitable cavities surrounding active Lewis's Woodpecker nests. Our results showed that cavity density best explained breeding performance differences although the mechanisms remain unclear. There was no evidence that the number of heterospecific nest competitors, including the invasive European Starling (Sturnus vulgaris), explained or influenced Lewis's Woodpecker breeding performance. Cavity density influenced the productivity of successful nests but did not explain habitat differences in hatching success or daily nest survival. Further work is required to understand the mechanistic basis for the habitat specific breeding performance of Lewis's Woodpeckers. Habitat differences in breeding performance in British Columbia are not consistent with those in other regions, highlighting the importance of regionally-specific demographic data for managing species at risk. [ABSTRACT FROM AUTHOR]

Recent developments in the social epidemiological literature indicate that health inequalities between the employed and the unemployed are widening in many advanced capitalist countries. At present, we know relatively little about why these inequalities are worsening. Drawing on nationally-representative data from the largest health survey in Canada, we explored this question by analyzing changes in self-rated health inequalities between employed and unemployed Canadians from 2000 to 2014. Using a regression-based method that decomposes a given inequality into its component sources, we investigated the extent to which risk factors that account for unemployment-related health inequalities at a single point in time can also explain the extent and direction of change in these unemployment-related health inequalities over time. Our results indicate that relative and absolute health inequalities between employed and unemployed Canadians widened over the study period. Between 2000 and 2014, the prevalence of poor self-rated health among unemployed Canadians increased from 10.8% to 14.6%, while rates among employed Canadians were stable at around 6%. Our findings suggest that the demographic, socioeconomic, and proximal risk factors that are routinely used to explain unemployment-related health inequalities may not be as powerful for explaining how and why these inequalities change over time. In the case of unemployment-related health inequalities in Canada, these risk factors explain neither the increasing prevalence of poor self-rated health among the unemployed nor the growing gap between the unemployed and their employed counterparts. We provide several possible explanations for these puzzling findings. We conclude by suggesting that widening health inequalities may be driven by macrosocial trends (e.g. widening income inequality and declining social safety nets) which have changed the meaning and context of unemployment, as well as its associated risk factors, in ways that are not easy to capture using routinely available survey data. [ABSTRACT FROM AUTHOR]

Emerald Basin on the Scotian Shelf off Nova Scotia, Canada, is home to a globally unique aggregation of the glass sponge Vazella pourtalesi, first documented in the region in 1889. In 2009, Fisheries and Oceans Canada (DFO) implemented two Sponge Conservation Areas to protect these sponge grounds from bottom fishing activities. Together, the two conservation areas encompass 259 km2. In order to ascertain the degree to which the sponge grounds remain unprotected, we modelled the presence probability and predicted range distribution of V. pourtalesi on the Scotian Shelf using random forest modelling on presence-absence records. With a high degree of accuracy the random forest model predicted the highest probability of occurrence of V. pourtalesi in the inner basins on the central Scotian Shelf, with lower probabilities at the shelf break and in the Fundian and Northeast Channels. Bottom temperature was the most important determinant of its distribution in the model. Although the two DFO Sponge Conservation Areas protect some of the more significant concentrations of V. pourtalesi, much of its predicted distribution remains unprotected (over 99%). Examination of the hydrographic conditions in Emerald Basin revealed that the V. pourtalesi sponge grounds are associated with a warmer and more saline water mass compared to the surrounding shelf. Reconstruction of historical bottom temperature and salinity in Emerald Basin revealed strong multi-decadal variability, with average bottom temperatures varying by 8°C. We show that this species has persisted in the face of this climatic variability, possibly indicating how it will respond to future climate change. [ABSTRACT FROM AUTHOR]

Background: Food insecurity is associated with a wide array of negative health outcomes and higher health care costs but there has been no population-based study of the association of food insecurity and mortality in high-income countries. Methods: We use cross-sectional population surveys linked to encoded health administrative data. The sample is 90,368 adults, living in Ontario and respondents in the Canadian Community Health Survey (CCHS). The outcome of interest is all-cause mortality at any time after the interview and within four years of the interview. The primary variable of interest is food insecurity status, with individuals classed as “food secure”, “marginally food insecure”, “moderately food insecure”, or “severely food insecure”. We use logistic regression models to determine the association of mortality with food insecurity status, adjusting for other social determinants of health. Results: Using a full set of covariates, in comparison to food secure individuals, the odds of death at any point after the interview are 1.28 (CI = 1.08, 1.52) for marginally food insecure individuals, 1.49 (CI = 1.29, 1.73) for moderately food insecure individuals, and 2.60 (CI = 2.17, 3.12) for severely food insecure individuals. When mortality within four years of the interview is considered, the odds are, respectively, 1.19 (CI = 0.95, 1.50), 1.65 (CI = 1.37, 1.98), and 2.31 (CI = 1.81, 2.93). Interpretation: These findings demonstrate that food insecurity is associated with higher mortality rates and these higher rates are especially large for the most severe food insecurity category. Efforts to reduce food insecurity should be incorporated into broader public health initiatives to reduce mortality. [ABSTRACT FROM AUTHOR]

Purpose: Women living with HIV experience high levels of trauma exposure before and after diagnosis. One of the most challenging outcomes following trauma exposure is posttraumatic stress disorder. Despite high exposure to traumatic events, the presence and contributors to posttraumatic stress disorder symptoms have not been examined in women living with HIV in Canada. Methods: The current study examines the presence of, contributors to, and geographical regions associated with self-reported posttraumatic stress symptoms (PTSS) among 1405 women enrolled in the Canadian HIV Women’s Sexual & Reproductive Health Cohort Study (CHIWOS). Results: Separate linear regression models were run for the three provinces in the cohort: British Columbia, Ontario and Québec. Scores consistent with posttraumatic stress disorder were reported by 55.9%, 39.1% and 54.1% of the participants in each province, respectively (F(2, 1402) = 13.53, p < .001). Conclusions: The results demonstrate that women living with HIV have high rates of PTSS, and that rates and variables associated with these symptoms vary by province. These results suggest the need for trauma-informed practices and care for women living with HIV in Canada, which may need to be tailored for the community and identities of the women. [ABSTRACT FROM AUTHOR]

Uncertainty remains regarding the magnitude of effectiveness of influenza vaccines for preventing serious outcomes, especially among young children. We estimated vaccine effectiveness (VE) against laboratory-confirmed influenza hospitalizations among children aged 6–59 months. We used the test-negative design in hospitalized children in Ontario, Canada during the 2010–11 to 2013–14 influenza seasons. We used logistic regression models adjusted for age, season, and time within season to calculate VE estimates by vaccination status (full vs. partial), age group, and influenza season. We also assessed VE incorporating prior history of influenza vaccination. We included specimens from 9,982 patient hospitalization episodes over four seasons, with 12.8% testing positive for influenza. We observed variation in VE by vaccination status, age group, and influenza season. For the four seasons combined, VE was 60% (95%CI, 44%-72%) for full vaccination and 39% (95%CI, 17%-56%) for partial vaccination. VE for full vaccination was 67% (95%CI, 48%-79%) for children aged 24–59 months, 48% (95%CI, 12%-69%) for children aged 6–23 months, 77% (95%CI, 47%-90%) for 2010–11, 59% (95%CI, 13%-81%) for 2011–12, 33% (95%CI, –18% to 62%) for 2012–13, and 72% (95%CI, 42%-86%) for 2013–14. VE in children aged 24–59 months appeared similar between those vaccinated in both the current and previous seasons and those vaccinated in the current season only, with the exception of 2012–13, when VE was lower for those vaccinated in the current season only. Influenza vaccination is effective in preventing pediatric laboratory-confirmed influenza hospitalizations during most seasons. [ABSTRACT FROM AUTHOR]

Background: With the Canadian government legalizing cannabis in the year 2018, the potential harms to certain populations—including those with opioid use disorder—must be investigated. Cannabis is one of the most commonly used substances by patients who are engaged in medication-assisted treatment for opioid use disorder, the effects of which are largely unknown. In this study, we examine the impact of baseline and ongoing cannabis use, and whether these are impacted differentially by gender. Methods: We conducted a retrospective cohort study using anonymized electronic medical records from 58 clinics offering opioid agonist therapy in Ontario, Canada. One-year treatment retention was the primary outcome of interest and was measured for patients who did and did not have a cannabis positive urine sample in their first month of treatment, and as a function of the proportion of cannabis-positive urine samples throughout treatment. Results: Our cohort consisted of 644 patients, 328 of which were considered baseline cannabis users and 256 considered heavy users. Patients with baseline cannabis use and heavy cannabis use were at increased risk of dropout (38.9% and 48.1%, respectively). When evaluating these trends by gender, only female baseline users and male heavy users are at increased risk of premature dropout. Interpretation: Both baseline and heavy cannabis use are predictive of decreased treatment retention, and differences do exist between genders. With cannabis being legalized in the near future, physicians should closely monitor cannabis-using patients and provide education surrounding the potential harms of using cannabis while receiving treatment for opioid use disorder. [ABSTRACT FROM AUTHOR]

In the United States and Canada, the most recent documented cases of rabies have been attributed to bat rabies viruses (RABV). We undertook this systematic review in an effort to summarize and enhance understanding of the risk of infection for individuals who have been potentially exposed to a suspect or confirmed rabid bat. United States rabies surveillance summaries documented a total of 41 human bat-rabies virus variant verified non-transplant cases between 1990 and 2015. All cases were fatal. Seven (17.1%) of 41 cases reported a bite from a bat. Ten (24.3%) cases had unprotected physical contact (UPC); these included seven cases that had a bat land or crawl on them (contact with claws) and one case that touched a bat’s teeth. Seven (17.1%) cases had probable UPC. Insectivorous bat teeth are extremely sharp and highly efficient for predation upon arthropod prey. Bats also have sharp claws on the end of their thumbs and feet. One of the most common bat RABV variants has an ability to replicate in non-neural cells. Questioning individuals about unprotected contact with bat teeth and claws (including a bat landing or crawling on a person) may help identify additional exposures. [ABSTRACT FROM AUTHOR]

Understanding the development of landscape patterns over broad spatial and temporal scales is a major contribution to ecological sciences and is a critical area of research for forested land management. Boreal forests represent an excellent case study for such research because these forests have undergone significant changes over recent decades. We analyzed the temporal trends of four widely-used landscape pattern indices for boreal forests of Canada: forest cover, largest forest patch index, forest edge density, and core (interior) forest cover. The indices were computed over landscape extents ranging from 5,000 ha (n = 18,185) to 50,000 ha (n = 1,662) and across nine major ecozones of Canada. We used 26 years of Landsat satellite imagery to derive annualized trends of the landscape pattern indices. The largest declines in forest cover, largest forest patch index, and core forest cover were observed in the Boreal Shield, Boreal Plain, and Boreal Cordillera ecozones. Forest edge density increased at all landscape extents for all ecozones. Rapidly changing landscapes, defined as the 90th percentile of forest cover change, were among the most forested initially and were characterized by four times greater decrease in largest forest patch index, three times greater increase in forest edge density, and four times greater decrease in core forest cover compared with all 50,000 ha landscapes. Moreover, approximately 18% of all 50,000 ha landscapes did not change due to a lack of disturbance. The pattern database results provide important context for forest management agencies committed to implementing ecosystem-based management strategies. [ABSTRACT FROM AUTHOR]

“Vaccine hesitancy” is a concept now frequently used in vaccination discourse. The increased popularity of this concept in both academic and public health circles is challenging previously held perspectives that individual vaccination attitudes and behaviours are a simple dichotomy of accept or reject. A consultation study was designed to assess the opinions of experts and health professionals concerning the definition, scope, and causes of vaccine hesitancy in Canada. We sent online surveys to two panels (1- vaccination experts and 2- front-line vaccine providers). Two questionnaires were completed by each panel, with data from the first questionnaire informing the development of questions for the second. Our participants defined vaccine hesitancy as an attitude (doubts, concerns) as well as a behaviour (refusing some / many vaccines, delaying vaccination). Our findings also indicate that both vaccine experts and front-line vaccine providers have the perception that vaccine rates have been declining and consider vaccine hesitancy an important issue to address in Canada. Diffusion of negative information online and lack of knowledge about vaccines were identified as the key causes of vaccine hesitancy by the participants. A common understanding of vaccine hesitancy among researchers, public health experts, policymakers and health care providers will better guide interventions that can more effectively address vaccine hesitancy within Canada. [ABSTRACT FROM AUTHOR]

Background: Computer-aided detection to identify and diagnose pulmonary tuberculosis is being explored. While both cavitation on chest radiograph and smear-positivity on microscopy are independent risk factors for the infectiousness of pulmonary tuberculosis it is unknown which radiographic pattern, were it detectable, would provide the greatest public health benefit; i.e. reduced transmission. Herein we provide that evidence. Objectives: 1) to determine whether pulmonary tuberculosis in a high income, low incidence country is more likely to present with “typical” adult-type pulmonary tuberculosis radiographic features and 2) to determine whether those with “typical” radiographic features are more likely than those without such features to transmit the organism and/or cause secondary cases. Methods: Over a three-year period beginning January 1, 2006 consecutive adults with smear-positive pulmonary tuberculosis in the Province of Alberta, Canada, were identified and their pre-treatment radiographs scored by three independent readers as “typical” (having an upper lung zone predominant infiltrate, with or without cavitation but no discernable adenopathy) or “atypical” (all others). Each patient’s pre-treatment bacillary burden was carefully documented and, during a 30-month transmission window, each patient’s transmission events were recorded. Mycobacteriology, radiology and transmission were compared in those with “typical” versus “atypical” radiographs. Findings: A total of 97 smear-positive pulmonary tuberculosis cases were identified, 69 (71.1%) with and 28 (28.9%) without “typical” chest radiographs. “Typical” cases were more likely to have high bacillary burdens and cavitation (Odds Ratios and 95% Confidence Intervals: 2.75 [1.04–7.31] and 9.10 [2.51–32.94], respectively). Typical cases were also responsible for most transmission events—78% of tuberculin skin test conversions (p<0.002) and 95% of secondary cases in reported close contacts (p<0.01); 94% of secondary cases in “unreported” contacts (p<0.02). Conclusion: As a group, smear-positive pulmonary tuberculosis patients with typical radiographic features constitute the greatest public health risk. This may have implications for automated detection systems. [ABSTRACT FROM AUTHOR]