Diarmid Campbell-Lendrum

Impact of regional climate change on human health.

The World Health Organisation estimates that the warming and precipitation trends due to anthropogenic climate change of the past 30 years already claim over 150,000 lives annually. Many prevalent human diseases are linked to climate fluctuations, from cardiovascular mortality and respiratory illnesses due to heatwaves, to altered transmission of infectious diseases and malnutrition from crop failures. Uncertainty remains in attributing the expansion or resurgence of diseases to climate change, owing to lack of long-term, high-quality data sets as well as the large influence of socio-economic factors and changes in immunity and drug resistance. Here we review the growing evidence that climate–health relationships pose increasing health risks under future projections of climate change and that the warming trend over recent decades has already contributed to increased morbidity and mortality in many regions of the world. Potentially vulnerable regions include the temperate latitudes, which are projected to warm disproportionately, the regions around the Pacific and Indian oceans that are currently subjected to large rainfall variability due to the El Niño/Southern Oscillation sub-Saharan Africa and sprawling cities where the urban heat island effect could intensify extreme climatic events.

Climate change and human health: impacts, vulnerability, and mitigation

It is now widely accepted that climate change is occurring as a result of the accumulation of greenhouse gases in the atmosphere arising from the combustion of fossil fuels. Climate change may affect health through a range of pathways--eg, as a result of increased frequency and intensity of heat waves, reduction in cold-related deaths, increased floods and droughts, changes in the distribution of vector-borne diseases, and effects on the risk of disasters and malnutrition. The overall balance of effects on health is likely to be negative and populations in low-income countries are likely to be particularly vulnerable to the adverse effects. The experience of the 2003 heat wave in Europe shows that high-income countries might also be adversely affected. Adaptation to climate change requires public-health strategies and improved surveillance. Mitigation of climate change by reducing the use of fossil fuels and increasing the use of a number of renewable energy technologies should improve health in the near term by reducing exposure to air pollution.

Public health benefits of strategies to reduce greenhouse-gas emissions: overview and implications for policy makers

This Series has examined the health implications of policies aimed at tackling climate change. Assessments of mitigation strategies in four domains-household energy, transport, food and agriculture, and electricity generation-suggest an important message: that actions to reduce greenhouse-gas emissions often, although not always, entail net benefits for health. In some cases, the potential benefits seem to be substantial. This evidence provides an additional and immediate rationale for reductions in greenhouse-gas emissions beyond that of climate change mitigation alone. Climate change is an increasing and evolving threat to the health of populations worldwide. At the same time, major public health burdens remain in many regions. Climate change therefore adds further urgency to the task of addressing international health priorities, such as the UN Millennium Development Goals. Recognition that mitigation strategies can have substantial benefits for both health and climate protection offers the possibility of policy choices that are potentially both more cost effective and socially attractive than are those that address these priorities independently.

Climate change and developing-country cities: implications for environmental health and equity.

Climate change is an emerging threat to global public health. It is also highly inequitable, as the greatest risks are to the poorest populations, who have contributed least to greenhouse gas (GHG) emissions. The rapid economic development and the concurrent urbanization of poorer countries mean that developing-country cities will be both vulnerable to health hazards from climate change and, simultaneously, an increasing contributor to the problem. We review the specific health vulnerabilities of urban populations in developing countries and highlight the range of large direct health effects of energy policies that are concentrated in urban areas. Common vulnerability factors include coastal location, exposure to the urban heat-island effect, high levels of outdoor and indoor air pollution, high population density, and poor sanitation. There are clear opportunities for simultaneously improving health and cutting GHG emissions most obviously through policies related to transport systems, urban planning, building regulations and household energy supply. These influence some of the largest current global health burdens, including approximately 800,000 annual deaths from ambient urban air pollution, 1.2 million from road-traffic accidents, 1.9 million from physical inactivity, and 1.5 million per year from indoor air pollution. GHG emissions and health protection in developing-country cities are likely to become increasingly prominent in policy development. There is a need for a more active input from the health sector to ensure that development and health policies contribute to a preventive approach to local and global environmental sustainability, urban population health, and health equity.

The epidemiology and control of leishmaniasis in Andean countries

This paper reviews the current knowledge of leishmaniasis epidemiology in Venezuela, Colombia, Ecuador, Peru, and Bolivia. In all 5 countries leishmaniasis is endemic in both the Andean highlands and the Amazon basin. The sandfly vectors belong to subgenera Helcocyrtomyia, Nyssomiya, Lutzomyia, and Psychodopygus, and the Verrucarum group. Most human infections are caused by Leishmania in the Viannia subgenus. Human Leishmania infections cause cutaneous lesions, with a minority of L. (Viannia) infections leading to mucocutaneous leishmaniasis. Visceral leishmaniasis and diffuse cutaneous leishmaniasis are both rare. In each country a significant proportion of Leishmania transmission is in or around houses, often close to coffee or cacao plantations. Reservoir hosts for domestic transmission cycles are uncertain. The paper first addresses the burden of disease caused by leishmaniasis, focusing on both incidence rates and on the variability in symptoms. Such information should provide a rational basis for prioritizing control resources, and for selecting therapy regimes. Secondly, we describe the variation in transmission ecology, outlining those variables which might affect the prevention strategies. Finally, we look at the current control strategies and review the recent studies on control.

Comparative risk assessment of the burden of disease from climate change.

The World Health Organization has developed standardized comparative risk assessment methods for estimating aggregate disease burdens attributable to different risk factors. These have been applied to existing and new models for a range of climate-sensitive diseases in order to estimate the effect of global climate change on current disease burdens and likely proportional changes in the future. The comparative risk assessment approach has been used to assess the health consequences of climate change worldwide, to inform decisions on mitigating greenhouse gas emissions, and in a regional assessment of the Oceania region in the Pacific Ocean to provide more location-specific information relevant to local mitigation and adaptation decisions. The approach places climate change within the same criteria for epidemiologic assessment as other health risks and accounts for the size of the burden of climate-sensitive diseases rather than just proportional change, which highlights the importance of small proportional changes in diseases such as diarrhea and malnutrition that cause a large burden. These exercises help clarify important knowledge gaps such as a relatively poor understanding of the role of nonclimatic factors (socioeconomic and other) that may modify future climatic influences and a lack of empiric evidence and methods for quantifying more complex climate–health relationships, which consequently are often excluded from consideration. These exercises highlight the need for risk assessment frameworks that make the best use of traditional epidemiologic methods and that also fully consider the specific characteristics of climate change. These include the long-term and uncertain nature of the exposure and the effects on multiple physical and biotic systems that have the potential for diverse and widespread effects, including high-impact events.

Domestic and peridomestic transmission of American cutaneous leishmaniasis: changing epidemiological patterns present new control opportunities

Predictions that deforestation would reduce American cutaneous leishmaniasis incidence have proved incorrect. Presentations at a recent international workshop, instead, demonstrated frequent domestication of transmission throughout Latin America. While posing new threats, this process also increases the effectiveness of vector control in and around houses. New approaches for sand fly control and effective targeting of resources are reviewed.

Climate change and health: on the latest IPCC report

www.thelancet.com Vol 383 April 5, 2014 1185 The Intergovernmental Panel on Climate Change (IPCC) released its latest report on March 31, 2014. This report was the second instalment of the Fifth Assessment Report, prepared by Working Group 2, on impacts, vulnerability, and adaptation to climate change. In this Comment, we, as contributors to the chapter on human health, explain how the IPCC report was prepared and highlight important fi ndings. The IPCC reviews and assesses the scientifi c published work on climate change. As an intergovernmental body composed of members of the UN, the IPCC does not undertake research itself; instead it appoints Working Groups who assess the work. This assessment means more than simply to summarise the state of knowledge: Working Groups are asked to weigh what has been written (in both peer-reviewed publications and grey literature), to make judgments about likelihood and uncertainty, and to fl ag important emerging issues. The focus for Working Group 2 was mainly, but not exclusively, on what had been written since the previous assessment in 2007; papers were eligible for inclusion if they were published, or accepted for publication, before Aug 31, 2013. The Working Groups were required to highlight what might be relevant to policy, but did not recommend policies. The Fifth Assessment Report Working Group 1 reported on the physical science of climate change in September, 2013 (appendix). Working Group 3, concerned with mitigation (ie, reduction of greenhouse gas emissions), will release its report in April, 2014. The scale of the enterprise is remarkable—indeed, reports by the IPCC together probably represent the largest scientifi c assessment exercise in history. There are 310 authors and review editors in Working Group 2, and an even greater number of contributing authors who have added to the report from their areas of special expertise. In addition to health, Working Group 2 examined natural and managed resources (eg, fresh water, coastal systems, and food production), human settlements, and other aspects of wellbeing such as security and livelihoods. The report (30 chapters) will be published in two volumes, and includes integrated assessments of impacts and adaptation in nine geographic regions and an overarching summary for policy makers. Work on the Fifth Assessment Report began 5 years ago (appendix) and aspects of the IPCC process distinguish its assessments from other reviews and scientifi c publications. One diff erence is the substantial role of member states in determination of, in the initial stages, the scope of the reports and the membership of writing groups. At the beginning of each round of assessment, meetings organised by the IPCC decide on the structure of the reports, including the number of chapters and the topics to be covered, and then member states nominate potential authors. The fi nal decision about authors is made by a subgroup from the IPCC, the Bureau, on the basis of scientifi c merit and the necessary institutional and disciplinary perspectives for each chapter, seeking, at the same time, to achieve a balance of representation by gender and region. Once appointed, the IPCC authors work independently; government input occurs as part of the peer review process. However, the member states must approve and sign off on the fi nal report. Thus, the IPCC assessments are the outputs of many iterative interactions between scientists and policy makers. Another feature of the IPCC process is the intensity of peer review. There were four rounds of review for the Fifth Assessment Report, two of which involved hundreds of self-nominated experts and scientists appointed by member-state governments. Each round generated an enormous number of comments, questions, and requests for change. For instance, the IPCC received 1009 reviewer comments just on the second-order draft of chapter 11 (human health). Two dedicated review editors per chapter are charged with ensuring that the authors consider each comment seriously and, if they reject it, that they do so with good reasons. Both the comments and the chapter authors’ responses will be published on the IPCC website. The IPCC does not prescribe how chapter groups should gather and interpret the scientifi c work, partly because conventions and practice diff er among disciplines. Contributors to the health chapter used many strategies to identify relevant published work. Due to the breadth of the topic, including the range of health outcomes and exposure pathways, the chapter team decided that one systematic review would not be possible. Climate change and health: on the latest IPCC report

Urban Environmental Health Hazards and Health Equity

This paper outlines briefly how the living environment can affect health. It explains the links between social and environmental determinants of health in urban settings. Interventions to improve health equity through the environment include actions and policies that deal with proximal risk factors in deprived urban areas, such as safe drinking water supply, reduced air pollution from household cooking and heating as well as from vehicles and industry, reduced traffic injury hazards and noise, improved working environment, and reduced heat stress because of global climate change. The urban environment involves health hazards with an inequitable distribution of exposures and vulnerabilities, but it also involves opportunities for implementing interventions for health equity. The high population density in many poor urban areas means that interventions at a small scale level can assist many people, and existing infrastructure can sometimes be upgraded to meet health demands. Interventions at higher policy levels that will create more sustainable and equitable living conditions and environments include improved city planning and policies that take health aspects into account in every sector. Health equity also implies policies and actions that improve the global living environment, for instance, limiting greenhouse gas emissions. In a global equity perspective, improving the living environment and health of the poor in developing country cities requires actions to be taken in the most affluent urban areas of the world. This includes making financial and technical resources available from high-income countries to be applied in low-income countries for urgent interventions for health equity. This is an abbreviated version of a paper on “Improving the living environment” prepared for the World Health Organization Commission on Social Determinants of Health, Knowledge Network on Urban Settings.

Chagas disease control in Venezuela: lessons for the Andean region and beyond

Following the success of the Southern Cone programme to control Chagas disease, Andean countries are beginning to implement a similar international initiative. Important lessons could be learnt from Venezuela, which has one of the longest running national control programmes in Latin America, but has received little attention in the scientific literature. Retrospective analysis of age-specific Trypanosoma cruzi seroprevalence data and entomological sampling indicates that while the programme successfully reduced the annual incidence of infection from approximately ten per 1000 people in the 1950s to one per 1000 in the 1980s, in the susceptible population of endemic areas, transmission has not yet been interrupted and could now be increasing. Andean governments can expect control to be highly effective, but must maintain long-term vigilance and targeted control measures to consolidate these gains.