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BackgroundAmbient air pollution is thought to contribute to increased risk of COVID-19, but the evidence is controversial.ObjectiveTo evaluate the associations between short-term variations in outdoor concentrations of ambient air pollution and COVID-19 emergency department (ED) visits.MethodsWe conducted a case-crossover study of 78 255 COVID-19 ED visits in Alberta and Ontario, Canada between 1 March 2020 and 31 March 2021. Daily air pollution data (ie, fine particulate matter with diameter less than 2.5 µm (PM2.5), nitrogen dioxide (NO2) and ozone were assigned to individual case of COVID-19 in 10 km × 10 km grid resolution. Conditional logistic regression was used to estimate associations between air pollution and ED visits for COVID-19.ResultsCumulative ambient exposure over 0–3 days to PM2.5 (OR 1.010; 95% CI 1.004 to 1.015, per 6.2 µg/m3) and NO2(OR 1.021; 95% CI 1.015 to 1.028, per 7.7 ppb) concentrations were associated with ED visits for COVID-19. We found that the association between PM2.5and COVID-19 ED visits was stronger among those hospitalised following an ED visit, as a measure of disease severity, (OR 1.023; 95% CI 1.015 to 1.031) compared with those not hospitalised (OR 0.992; 95% CI 0.980 to 1.004) (p value for effect modification=0.04).ConclusionsWe found associations between short-term exposure to ambient air pollutants and COVID-19 ED visits. Exposure to air pollution may also lead to more severe COVID-19 disease.

Objectives: This study aimed at (1) describing the local risk of West Nile virus (WNV) infection in humans based on previous case reports and (2) investigating the spatial clustering of cases in the five most affected administrative regions of Quebec, Canada, for the 2011–2016 period. Methods: Human WNV cases declared to the Ministry of Health and Social Services of Quebec (Ministère de la santé et des services sociaux, MSSS) were retrieved. Incidence risk by age and sex was calculated for the study period. The yearly and monthly occurrence of cases in geographical units (GUs) was described and the probability of observing cases in a GU with cases reported in the previous year or month was assessed. Moran’s I was used to assess global clustering across the study area. Spatial clusters were identified by the Kulldorff scan statistic. Results: A total of 261 WNV cases were declared to the MSSS between 2011 and 2016 in the study area. Overall, a low percentage of GU with cases reported had additional cases reported over the next month or year. Global spatial clustering was weak but statistically significant (p< 0.05) for 2012 and 2015. For these two years, spatial clusters of high-risk GUs were identified. Conclusion: Results underline the challenge of predicting the distribution of WNV incidence risk in Quebec based on previous occurrence of human cases. Ongoing research with high spatial resolution entomological data is still necessary to understand the spatial distribution of risk at a local scale.

In North America, different strains of the Lyme disease-causing bacterium Borrelia burgdorferisensu stricto cluster into phylogenetic groups that are associated with different levels of pathogenicity and, for some, specific rodent reservoir hosts. Here we explore whether landscape connectivity, by impacting host dispersal, influences B. burgdorferis.s. spread patterns. This question is central to modelling spatial patterns of the spread of Lyme disease risk in the zone of northward range-expansion of B. burgdorferis.s. in southeastern Canada where the study was conducted. We used multi-locus sequence typing (MLST) to characterise B. burgdorferis.s. in positive ticks collected at 13 sites in southern Quebec, Canada during the early stages of B. burgdorferis.s. invasion. We used mixed effects logistic regression to investigate whether landscape connectivity (probability of connectivity; PC) affected the probability that samples collected at different sites were of the same strain (MLST sequence type: ST). PC was calculated from a habitat map based on high spatial resolution (15 m) Landsat 8 imagery to identify woodland habitat that are preferred by rodent hosts of B. burgdorferis.s. There was a significant positive association between the likelihood that two samples were of the same ST and PC, when PC values were grouped into three categories of low, medium and high. When analysing data for individual STs, samples at different sites were significantly more likely to be the same when PC was higher for the rodent-associated ST1. These findings support the hypothesis that dispersion trajectories of B. burgdorferis.s. in general, and some rodent-associated strains in particular, are at least partly determined by landscape connectivity. This may suggest that dispersion of B. burgdorferis.s. is more common by terrestrial mammal hosts (which would likely disperse according to landscape connectivity) than by birds, the dispersal of which is likely less constrained by landscape. This study suggests that accounting for landscape connectivity may improve model-based predictions of spatial spread patterns of B. burgdorferis.s. The findings are consistent with possible past dispersal patterns of B. burgdorferis.s. as determined by phylogeographic studies.

Public health management of Lyme disease (LD) is a dynamic challenge in Canada. Climate warming is driving the northward expansion of suitable habitat for the tick vector, Ixodes scapularis. Information about tick population establishment is used to inform the risk of LD but is challenged by sampling biases from surveillance data. Misclassifying areas as having no established tick population underestimates the LD risk classification.

RésuméCet article rend compte de la mise en place d'un système opérationnel de suivi de l'orpaillage clandestin en milieu forestier tropical qui facilitera la gouvernance du territoire forestier guyanais. Il constitue une plateforme utilisant la télédétection spatiale pour surveiller en temps réel l'activité minière en forêt. L'outil bénéficie de l'appui d'une station de réception satellite sur place. Le protocole d'analyse est entièrement automatisé ce qui rend le système plus fiable et moins sujet aux erreurs. Les données géospatiales qui en sont tirées sont utilisables par les services de l'État sous format cartographique tel un outil de surveillance permettant d'aider les décideurs locaux dans les choix d'intervention. Cet outil de décision est un support majeur à la gouvernance territorial puisque le territoire guyanais est immense et peu accessible. Dans un contexte d'exploitation clandestin de l'or en recrudescence en Guyane et de la prise de conscience des enjeux environnementaux, le choix a été fait de développer pour les services de l'Etat un outil de gouvernance territoriale. Mis à l'essai depuis 2008, cet outil laisse entrevoir un potentiel intéressant dans plusieurs secteurs d'application, entre autres dans l'agriculture et la préservation des espaces naturels. Il est souhaitable que cette plateforme permette d'améliorer la gouvernance territoriale de la Guyane.