key: cord-0971128-0gui0qln
authors: Heffernan, Claire
title: Climate change and infectious disease: time for a new normal?
date: 2015-01-19
journal: Lancet Infect Dis
DOI: 10.1016/s1473-3099(14)71077-1
sha: 421345e3b0e9f279bb923b8db1bd989999b54da3
doc_id: 971128
cord_uid: 0gui0qln

nan

Causal relations remain elusive to many researchers, even for infectious diseases with clear climate eff ects such as vector-borne, arboviral, and parasitic disease. 4 An equally prevalent view was that climate change was the crucial game changer in terms of our understanding of infectious disease. Indeed, there have been calls for global warming to be viewed as a health threat itself. 5 Part of the problem is that much of the early research into climate change and infectious disease focused on proving how "coupled" or "decoupled" particular diseases are with climate eff ects. 6 Thus, climate change was often viewed as a unique and discreet driver of disease. 7 Unsurprisingly, this conceptualisation forged an evidence base that is both highly specifi c and often polarised.

Yet climate change is clearly an embedded context in which changes to the susceptibility and infectiousness of human and animal diseases-and thereby their emergence or transmission-occur. We know that climate change has direct and indirect eff ects on a range of diseases. Furthermore, climate disruption is likely to have multiplier eff ects between both diseases and drivers. Finally, climate warming could potentially forge a cascade of both biotic and abiotic events or factors leading to disease emergence and re-emergence. Such a cumulative or cascade eff ect could clearly set the scene for collective disease events in global health. www.thelancet.com/infection Vol 15 February 2015

These notions are not entirely new. In 1999, the International Red Cross predicted that climate change and poverty would trigger a decade of so-called superdisasters, including disease epidemics. 8 More than two decades later, extreme weather events have caused a range of humanitarian crises. Although a cumulative or multiplier eff ect merging such events into a single superdisaster has not come to pass, the increasing frequency of these events raises the threat of such an occurrence. Similarly, the emergence of a range of global pandemics or panzootics from severe acute respiratory syndrome to highly pathogenic avian infl uenza enables us to envision the potential eff ects on health services of multiple emerging infectious disease events.

From the outset, the identifi cation of the forces behind such potential multiple disease events is likely to demand a deeper understanding of the inter-relationships and synergies between the myriad of factors important to change within the context of both human and animal health. Clearly in the context of multiple emerging infectious disease events, the additive eff ects of climate on a range of other drivers are what matters.

The recognition of key gaps in our knowledge has led to a call for transdisciplinary inquiries across global health. 9 However, although such an approach is necessary, it is unlikely to be suffi cient. 10 Rather, to explore climate change as an embedded context demands that we explicate the synergies and interrelations between drivers, between diseases, and between both drivers and diseases. Ascertainment of the scope and direction of these interactions is an essential fi rst step towards better elucidating the eff ect of climate change on infectious disease. Therefore, perhaps it is time for a new "normal" in global health that views the human, wildlife, and livestock disease burden in any given geographical area as greater than the sum of its parts. In this approach, understanding the absence of a disease might be as important as identifying the specifi c factors driving disease emergence and transmission. Explorations of the collective disease burden across species might better explain the role and interaction of climate than the current focus on specifi c drivers and individual diseases. In this approach, assessments of risk, vulnerabilities, and interactions across these collective versus absent disease states could begin to forge a wider understanding of the role and eff ect (both present and future) of climate change on disease.

To ascribe to such a wider framework is likely to only enhance, rather than limit, our understanding of the dynamics of infectious disease and climate change. Such an approach can certainly work in tandem with the recommendations from global conferences, meetings, and researchers. 1,2,11 However, the creation of this new episteme will depend on our inherent fl exibility to reach beyond existing constructs and explore absences in addition to emergences and synergies, and the direct drivers of infectious disease. The future is in our hands; is it time to forge a new normal? 

The Lancet. Climate change and health, action please not words

Health risks of climate change: act now or pay later

Opening remarks on the conference on health and climate. WHO Conference on Health and Climate

Is expert opinion enough? A critical assessment of the evidence for potential impacts of climate change on tick-borne diseases

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Health and climate conference plenary session. WHO Conference on Health and Climate