Dominique F. Charron

A role of high impact weather events in waterborne disease outbreaks in Canada, 1975 – 2001

Abstract Recent outbreaks of Escherichia coli O157:H7, Campylobacter, and Cryptosporidium have heightened awareness of risks associated with contaminated water supply. The objectives of this research were to describe the incidence and distribution of waterborne disease outbreaks in Canada in relation to preceding weather conditions and to test the association between high impact weather events and waterborne disease outbreaks. We examined extreme rainfall and spring snowmelt in association with 92 Canadian waterborne disease outbreaks between 1975 and 2001, using case-crossover methodology. Explanatory variables including accumulated rainfall, air temperature, and peak stream flow were used to determine the relationship between high impact weather events and the occurrence of waterborne disease outbreaks. Total maximum degree-days above 0°C and accumulated rainfall percentile were associated with outbreak risk. For each degree-day above 0°C the relative odds of an outbreak increased by a factor of 1.007 (95% confidence interval [CI] = 1.002 – 1.012). Accumulated rainfall percentile was dichotomized at the 93rd percentile. For rainfall events greater than the 93rd percentile the relative odds of an outbreak increased by a factor of 2.283 (95% [CI] = 1.216 – 4.285). These results suggest that warmer temperatures and extreme rainfall are contributing factors to waterborne disease outbreaks in Canada. This could have implications for water management and public health initiatives.

VULNERABILITY OF WATERBORNE DISEASES TO CLIMATE CHANGE IN CANADA: A REVIEW

This project addresses two important issues relevant to the health of Canadians: the risk of waterborne illness and the health impacts of global climate change. The Canadian health burden from waterborne illness is unknown, although it presumably accounts for a significant proportion of enteric illness. Recently, large outbreaks with severe consequences produced by E. coli O157:H7 and Cryptosporidium have alarmed Canadians and brought demands for political action. A concurrent need to understand the health impacts of global climate changes and to develop strategies to prevent or prepare for these has also been recognized. There is mounting evidence that weather is often a factor in triggering waterborne disease outbreaks. A recent study of precipitation and waterborne illness in the United States found that more than half the waterborne disease outbreaks in the United States during the last half century followed a period of extreme rainfall. Projections of international global climate change scenarios suggest that, under conditions of global warming most of Canada may expect longer summers, milder winters, increased summer drought, and more extreme precipitation. Excess precipitation, floods, high temperatures, and drought could affect the risk of waterborne illness in Canada. The existing scientific information regarding most weather-related adverse health impacts and on the impacts of global climate change on health in Canada is insufficient for informed decision making. The results of this project address this need through the investigation of the complex systemic interrelationships between disease incidence, weather parameters, and water quality and quantity, and by projecting the potential impact of global climate change on those relationships.

Investigation of relationships between temperature and developmental rates of tick Ixodes scapularis (Acari: Ixodidae) in the laboratory and field.

Abstract Relationships between temperature and preoviposition, preeclosion, and premolt developmental periods for the tick Ixodes scapularis Say were investigated by holding field-collected ticks in the laboratory at temperatures of 0 to 32°C at constant daylength. The duration of these developmental periods decreased significantly with increasing temperature. Host of origin, prior storage at 4°C, and season of collection of the ticks were also significantly associated with variations in the duration of the preoviposition period. For each developmental stage, the effect of temperature on development rate was best described as a power relationship. Laboratory-derived relationships were used to predict dates for molting, oviposition, and eclosion of engorged larvae and nymphs, engorged adult females and egg masses, respectively, placed in the field during 1989–1992. Predicted dates for oviposition by adult females, eclosion of eggs, and molting of engorged larvae were within 2 wk of the observed dates, and field-observed seasonal activity of questing larvae and nymphs also was predicted well by laboratory data. Molting of engorged nymphs and seasonal activity of questing adult ticks were, however, poorly predicted. Our findings suggest that duration of development in the field, of larvae from engorged adult females, and of nymphs from engorged larvae, may be explained largely by temperature effects alone, whereas emergence of adult I. scapularis from engorged nymphs may depend on temperature-independent diapause phenomena. The significance of these findings for understanding current and future distributions of I. scapularis, and of the pathogens it transmits, is discussed.

Ixodes scapularis Ticks Collected by Passive Surveillance in Canada: Analysis of Geographic Distribution and Infection with Lyme Borreliosis Agent Borrelia burgdorferi

Abstract Passive surveillance for the occurrence of the tick Ixodes scapularis Say (1821) and their infection with the Lyme borreliosis spirochaetes Borrelia burgdorferi s.l. has taken place in Canada since early 1990. Ticks have been submitted from members of the public, veterinarians, and medical practitioners to provincial, federal, and university laboratories for identification, and the data have been collated and B. burgdorferi detected at the National Microbiology Laboratory. The locations of collection of 2,319 submitted I. scapularis were mapped, and we investigated potential risk factors for I. scapularis occurrence (in Québec as a case study) by using regression analysis and spatial statistics. Ticks were submitted from all provinces east of Alberta, most from areas where resident I. scapularis populations are unknown. Most were adult ticks and were collected in spring and autumn. In southern Québec, risk factors for tick occurrence were lower latitude and remote-sensed indices for land cover with woodland. B. burgdorferi infection, identified by conventional and molecular methods, was detected in 12.5% of 1,816 ticks, including 10.1% of the 256 ticks that were collected from humans and tested. Our study suggests that B. burgdorferi-infected I. scapularis can be found over a wide geographic range in Canada, although most may be adventitious ticks carried from endemic areas in the United States and Canada by migrating birds. The risk of Lyme borreliosis in Canada may therefore be mostly low but more geographically widespread than previously suspected.

Investigation of Ground Level and Remote-Sensed Data for Habitat Classification and Prediction of Survival of Ixodes scapularis in Habitats of Southeastern Canada

Abstract In southeastern Canada, most populations of Ixodes scapularis Say, the Lyme disease vector, occur in Carolinian forests. Climate change projections suggest a northward range expansion of I. scapularis this century, but it is unclear whether more northerly habitats are suitable for I. scapularis survival. In this study, we assessed the suitability of woodlands of the Lower Great Lakes/St. Lawrence Plain region for I. scapularis by comparing tick egg survival in four different woodlands. Woodlands where I. scapularis are established, and sand dune where I. scapularis do not survive, served as positive and negative control sites, respectively. At two woodland sites, egg survival was the same as at the positive control site, but at two of the sites survival was significantly less than either the positive control site, or one of the other test sites. Egg survival in all woodland sites was significantly higher than in the sand dune site. Ground level habitat classification discriminated among woodlands in which tick survival differed. The likelihood that I. scapularis populations could persist in the different habitats, as deduced using a population model of I. scapularis, was significantly associated with variations in Landsat 7 ETM+ data (normalized difference vegetation index [NDVI] and Tasselled Cap indices). The NDVI index predicted habitat suitability at Long Point, Ontario, with high sensitivity but moderate specificity. Our study suggests that I. scapularis populations could establish in more northerly woodland types than those in which they currently exist. Suitable habitats may be detected by ground-level habitat classification, and remote-sensed data may assist this process.

Ecosystem Approaches to Health for a Global Sustainability Agenda

International research agendas are placing greater emphasis on the need for more sustainable development to achieve gains in global health. Research using ecosystem approaches to health, and the wider field of ecohealth, contribute to this goal, by addressing health in the context of inter-linked social and ecological systems. We review recent contributions to conceptual development of ecosystem approaches to health, with insights from their application in international development research. Various similar frameworks have emerged to apply the approach. Most predicate integration across disciplines and sectors, stakeholder participation, and an articulation of sustainability and equity to achieve relevant actions for change. Drawing on several frameworks and on case studies, a model process for application of ecosystem approaches is proposed, consisting of an iterative cycles of participatory study design, knowledge generation, intervention, and systematization of knowledge. The benefits of the research approach include innovations that improve health, evidence-based policies that reduce health risks; empowerment of marginalized groups through knowledge gained, and more effective engagement of decision makers. With improved tools to describe environmental and economic dimensions, and explicit strategies for scaling-up the use and application of research results, the field of ecohealth will help integrate both improved health and sustainability into the development agenda.

Ecohealth: Origins and Approach

Improving people’s health, while promoting thriving, resilient communities and environmental sustainability, is one of the great development challenges for the twenty-first century. This book is about how a growing international field of research, education, and practice called ecohealth is tackling this challenge, and using innovative ideas to build healthier communities and environments in developing countries.

Health and sustainable development: challenges and opportunities of ecosystem approaches in the prevention and control of dengue and Chagas disease

Um mundo de pessoas saudaveis em ecossistemas saudaveis tem sido uma meta elusiva da agenda de desenvolvimento sustentavel. Inumeras avaliacoes de bases cientificas concordam com a interdependencia fundamental entre saude, economia e ambiente e, com a urgencia de melhores determinacoes e orquestracao de acoes baseadas em enfoques participativos multissetoriais em niveis local e global. Para tornar o conhecimento relevante para fundamentar politicas publicas direcionadas para o desenvolvimento sustentavel e saudavel e necessario considerar as interacoes complexas e dinâmicas entre sistemas ecologicos e sociais (enfoque sistemico), que devem estar ligadas as acoes de desenvolvimento. Isso requer maior interacao entre tomadores(as) de decisoes, pesquisadores(as) e representantes da sociedade civil - um processo participativo com multiplos atores, e a integracao de diferentes disciplinas e de diferentes tipos de conhecimento em um enfoque transdisciplinar. Enfoques ecossistemicos para saude humana (ecossaude) conecta esses elementos em um esquema adaptavel para pesquisa e acao. Este artigo apresenta exemplos de pesquisas com enfoque em ecossaude aplicadas as enfermidades transmitidas por vetores, com atencao particular a participacao de multiplos atores, considerando a proeminencia desta prerrogativa no discurso politico de desenvolvimento sustentavel.A world of healthy people living in healthy ecosystems has proven to be an elusive goal of the sustainable development agenda. Numerous science-based assessments agree on the fundamental interdependence between peoples health, the economy, and the environment, and on the urgency for more determined and concerted action based on multi-sector participatory approaches at the global and local levels. For knowledge to be policy-relevant and capable of contributing to healthy and sustainable development, it must take into account the dynamic and complex interactions between ecological and social systems (systems thinking), and it must be linked to development actions. This in turn requires greater interaction and exchange between decision-makers, researchers and civil society (a multi-stakeholder participatory process); and the harnessing of different disciplines and of different kinds of knowledge (a transdisciplinary approach). Ecosystem approaches to human health (ecohealth) link these elements in an adaptable framework for research and action. This paper presents an overview of ecohealth research approaches applied to vector-borne diseases, with particular attention to multi-stakeholder participation given its prominence in the sustainable development policy discourse.A world of healthy people living in healthy ecosystems has proven to be an elusive goal of the sustainable development agenda. Numerous science-based assessments agree on the fundamental interdependence between peoples health, the economy, and the environment, and on the urgency for more determined and concerted action based on multi-sector participatory approaches at the global and local levels. For knowledge to be policy-relevant and capable of contributing to healthy and sustainable development, it must take into account the dynamic and complex interactions between ecological and social systems (systems thinking), and it must be linked to development actions. This in turn requires greater interaction and exchange between decision-makers, researchers and civil society (a multi-stakeholder participatory process); and the harnessing of different disciplines and of different kinds of knowledge (a transdisciplinary approach). Ecosystem approaches to human health (ecohealth) link these elements in an adaptable framework for research and action. This paper presents an overview of ecohealth research approaches applied to vector-borne diseases, with particular attention to multi-stakeholder participation given its prominence in the sustainable development policy discourse.

Ecohealth Research in Practice

This book presents innovative research from the field of ecosystem approaches to health that addresses health problems arising at the nexus of economic development and deteriorated ecosystems or changing environments. In addition to seeking new knowledge and understanding, the research has sought to support change processes that will enable people to achieve better health as well as ecologically, socially, and economically sustainable development.

Sleeping Sickness in Southeastern Uganda: A Systems Approach

Sleeping sickness continues to be a significant public health burden in southeastern Uganda. Continued spread of the disease into new areas of Uganda highlights our inability to understand and predict the distribution of infection. Multiple factors influence the distribution of sleeping sickness, including climate, land cover, cattle movements, prevention and control activities, and social conflict. We draw on a systems approach to conceptualize and characterize the multiple interacting forces and processes that influence the spatial and temporal dynamics of sleeping sickness in Uganda. This synthesis reveals a complex system of interactions among human and biophysical systems, feedback, and scale dependence. We identify some common analytical modeling approaches relative to our system characterization and identify opportunities for sleeping sickness research and improved understanding of disease dynamics in Uganda.