Global Climate Change and Extreme Weather Events Understanding the Contributions to Infectious Disease Emergence: Workshop Summary (2008) / Chapter Skim
Currently Skimming:
Summary and Assessment
Summary and Assessment
Pages 1-53
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 1... ...
is leading researchers to view the long-standing relationships between climate and disease from a global perspective. Increased atmospheric and surface temperatures are already contributing to the worldwide burden of disease and premature deaths, and are anticipated to influence the transmission dynamics and geographic distribution of malaria, dengue fever, tick-borne diseases, and diarrheal diseases such as cholera (IPCC, 2007a)
|
From page 2... ...
held a public workshop in Washington, DC, on December 4 and 5, 2007, to explore the anticipated direct and indirect effects of global climate change and extreme weather events on infectious diseases of humans, animals, and plants and the implications of these health impacts for global and national security. Through invited presentations and discussions, invited speakers considered a range of topics related to climate change and infectious diseases, including the ecological and environmental contexts of climate and infectious diseases; direct and indirect influences of extreme weather events and climate change on infectious diseases; environmental trends and their influence on the transmission and geographic range of vector- and non-vector-borne infectious diseases; opportunities and challenges for the surveillance, prediction, and early detection of climate-related outbreaks of infectious diseases; and the international policy implications of the potentially far-reaching impacts of climate change on infectious disease.
|
From page 3... ...
. Its key findings, summarized in Box SA-1, reflect considerable scientific uncertainty regarding the causal relationship between global climate change and infectious disease emergence. Emerging infectious diseases are caused by pathogens that (1)
|
From page 4... ...
• The potential disease impacts of global climate change remain highly uncertain. • Climate change may affect the evolution and emergence of infectious diseases.
|
From page 5... ...
. • Hydrological extremes: Warming of the global climate system accelerates the hydrological cycle, producing more droughts, floods, and other extreme weather events.
|
From page 6... ...
As discussed in subsequent sections of this summary and in Chapter 1, extreme weather conditions increase the risk of transmission for a variety of infectious diseases, including diarrheal diseases, vector-borne diseases, and respiratory infections. Following a weather disaster such as a hurricane, affected areas must often cope with multiple infectious disease outbreaks.
|
From page 7... ...
SOURCE: U.S. Climate Change Science Program and the Subcommittee on Global Change Research (2008)
|
From page 8... ...
Additional methods are used to analyze data gathered across scientific disciplines in order to reveal patterns and emerging trends associated with climate change, calculate rates of change (i.e., in the geographic range, prevalence, and incidence of infectious diseases) , and compare these observations with predicted outcomes.
|
From page 9... ...
. Ecological opportunists -- including insects and rodents that serve as vectors of, and reservoirs for, infectious diseases -- tend to proliferate rapidly in disturbed environments, while large predator species (infectious disease hosts)
|
From page 10... ...
has concluded, "it would appear that we may be underestimating the breadth of biologic responses to changes in climate." Figure SA-2 illustrates the multiple pathways by which variations in climate affect the health of humans, animals, and plants. Direct influences include long-term regional changes in average temperature and precipitation, as well as extreme weather events such as floods, droughts, or violent storms.
|
From page 11... ...
Adverse Health Effects Heat-Related Illnesses and Deaths Extreme Weather Related Health Effects Changes in Intermediate Factors Regional and Local Weather Change Air Pollution Concentration Air Pollution Natural and Climate Variability and Distribution Related Health Effects Human Influences and Change Extreme Weather on Climate Temperature Pollen Production Allergic Diseases Precipitation Infectious Diseases Water- and Microbial Contamination Food-Borne Diseases and Transmission Vector- and Rodent-Borne Diseases Crop Yield Malnutrition Mitigation Policies Storm Surge-Related Change in Coastal Flooding Drowning and Injuries Sea Level Coastal Aquifer Salinity Health Problems of Displaced Populations Moderating Influences and Adaptation Measures Mitigation Policies for Reduction Moderating Influences Adaptation Measures of Greenhouse Gas Emissions Population Density and Growth Vaccination Programs Energy Efficiency Level of Technological Development Disease Surveillance Use of Renewable Energy Sources Standard of Living and Local Environmental Condition Protective Technologies Forest Preservation Preexisting Health Status Weather Forecasting and Warning Systems Quality and Access to Health Care Emergency Management and Disaster Preparedness Public Health Infrastructure Public Health Education and Prevention Legislation and Administration FIGURE SA-2 Potential health effects of climate variability and change. SOURCE: Reprinted with permission from the American Medical Association from Haines and Patz (2004)
|
From page 12... ...
These include reservoir species for infectious diseases, such as migratory birds that carry avian influenza. Climate also influences the distribution and transmission of infectious diseases through indirect effects on local ecosystems and human behavior.
|
From page 13... ...
. Observed Effects of Climate Variation on Infectious Disease Range and Transmission Dynamics The many factors confounding the interrelationships between climate change and infectious disease emergence vastly complicate attempts to investigate causality.
|
From page 14... ...
The microbe-host interaction is influenced by the interlocking domains of the determinants of the emergence of infection: genetic and biological factors; physical environmental factors; ecological factors; and social, political, and economic factors.
|
From page 15... ...
Infectious Diseases in New Places The following illustrative examples suggest that climate change has contributed to recent shifts in the geographic distribution of certain vector-borne diseases. In each case, additional factors may also contribute to the emergence and spread of these diseases.
|
From page 16... ...
. Climate Variation and Infectious Disease Transmission Several recent studies have examined the relationship between short-term climatic variation and the occurrence of infectious diseases, in particular the influence of the El Niño/Southern Oscillation (ENSO)
|
From page 17... ...
HPS, PL CHOL MAL DENG CHOL MAL DENG RVF DENG Dengue Fever CHOL Cholera MAL Malaria RVF Rift Valley Fever HPS Hanta Virus Pulmonary Syndrome PL Plague FIGURE SA-6 Hot spots of potential elevated risk for disease outbreaks under El Niño conditions, 2006-2007. SOURCE: Anyamba et al.
|
From page 18... ...
Department of Defense, described key examples of such research, which examined connections between ENSOrelated weather extremes and two infectious diseases: RVF and chikungunya fever (see Chretien in Chapter 2)
|
From page 19... ...
affect atmospheric circulation patterns such that there is an increase in rainfall over a large area of eastern Africa, which can lead to large-scale outbreaks of mosquito-borne diseases (NASA Goddard Space Flight Center, 2000)
|
From page 20... ...
According to the Global Inventory Modeling and Mapping Studies (GIMMS) Group at the NASA Goddard Space Flight Center, the El Niño event of 2006-2007 was manifest by anomalous warming (~+2 oC)
|
From page 21... ...
. In addition to ENSO-associated weather anomalies, other short-term variations in climate, including drought, temperature, and wind patterns, have also been linked with changes in infectious disease incidence and geographic range: Drought and diarrheal disease While diarrheal disease is frequently associated with periods of heavy rainfall and flooding and the subsequent contamination of water supplies with fecal bacteria (NRC, 2001)
|
From page 22... ...
Synergies and Threshold Effects of Climate Change on Infectious Disease Emergence In addition to the short-term observations of the effects of climate variation on the range and transmission of infectious disease described in the previous section, workshop participants considered the apparent near-term and long-range impacts of climate change on infectious diseases in several illustrative contexts: plant communities and crops; aquatic and marine environments; the Arctic; and central Asian ecosystems that have long served as incubators for plague epidemics. A common theme uniting these diverse accounts was the recognition that climate does not act gradually or entirely predictably upon ecosystems, but combines with other influences to produce threshold effects.
|
From page 23... ...
Research is also needed to identify and improve the introduction of disease resistance genes, a proven and promising strategy for responding to changes in disease threats to crops. In the tropics, where climate change is viewed as a considerable threat to food security due to the likelihood of greater climate variability, and where resources for crop protection are limited, efforts to characterize genetic resources are especially important.
|
From page 24... ...
In addition to these relationships, Dierauf emphasized that because aquatic and marine ecosystems are interconnected, infectious diseases of fish and wildlife may have the opportunity to move from freshwater sources to intertidal zones to marine environments, affecting species that may have not encountered these disease agents before. She also noted the particular vulnerability of coastal and intertidal zones to the effects of extreme weather, both directly as a result of damaging winds and water and indirectly though runoff from inland floods.
|
From page 25... ...
and background repaired as much as possible Water-borne human disease The incidence and distribution of food- and waterborne diseases are shaped by numerous factors, including climate variation, water temperature, precipitation patterns, and/or water salinity. Extreme weather events, including heavy rainfall and flooding, are associated with outbreaks of several important water-borne diseases (NRC, 2001)
|
From page 26... ...
is a newly discovered viral disease associated with large-scale mortality of many common fish species. The virus is able to survive in warm and cold waters and in estuarine and marine waters, as well as in freshwater systems (see Figure SA-10)
|
From page 27... ...
SUMMARY AND ASSESSMENT 27 • Chytridiomycosis (Batrachochytrium dendrobatidis) is a fungal infection of not only North American frogs, but is now being detected worldwide (see Figure SA-11)
|
From page 28... ...
. This trend is expected to continue and intensify, resulting in warmer winters, increased annual precipitation, more frequent extreme weather events, and -- as the ice continues to melt -- greater river discharge and increased sea height, according to workshop speaker Alan Parkinson, of the CDC's Arctic Investigations Program in Anchorage, Alaska.
|
From page 29... ...
. As temperatures increase, reservoir species for zoonotic diseases may survive winters in larger numbers, increase in population, or expand their geographic ranges.
|
From page 30... ...
Public health challenges Together with a catalog of health impacts attributable to climate change in the Arctic, Parkinson noted two indirect effects that appear especially favorable to infectious disease transmission: (1) damage to the sanitation infrastructure resulting from the melting of permafrost (upon which many Arctic communities are built)
|
From page 31... ...
Bitmapped ernmost communities, Parkinson noted, but it is also likely to expose the region's inhabitants and ecosystems to invasive species of all kinds, including potentially pathogenic microbes and their vectors. In the face of these challenges, Parkinson echoed the suggestions of many other speakers at this workshop to enhance the surveillance and monitoring of climate-sensitive infectious diseases on a global basis and to establish international networks to share such information.
|
From page 32... ...
Historical, Scientific, and Technological Approaches Several workshop presentations described methods used to identify, measure, analyze, and predict the direct and indirect effects of climate change on infectious disease emergence. Each of the topics discussed below represents part of an interdisciplinary approach that, participants agreed, must continue to expand in order to pursue a common goal.
|
From page 33... ...
. Long-term monitoring of infectious diseases in wildlife also made possible the previously described model of plague dynamics and climate by Stenseth and coworkers (Stenseth et al., 2006)
|
From page 34... ...
Predictive Models Several models for predicting the onset or prevalence of infectious diseases based on climatic indicators have been discussed in previous sections of this chapter (see also contributions to Chapter 2 by Chretien, Colwell, and Stenseth)
|
From page 35... ...
"These relationships are very complex and have to be developed for specific biomes." Thus, the California Mosquito-borne Encephalitis Virus Surveillance and Response Plan currently incorporates measures of climate variation; however, the researchers are refining their models with the goal of using climate forecasts to provide earlier warning of transmission risk. Challenges As they explored the various routes by which climate variability and extreme weather events influence infectious disease emergence, workshop participants identified a range of challenges inherent to research on this topic.
|
From page 36... ...
Similarly, a predictive model that highlights regions at higher risk for infectious disease emergence (see Figure SA-15) suggests that such "hot spots" are concentrated in equatorial developing countries, where opportunities for monitoring and research are severely limited (Jones et al., 2008)
|
From page 37... ...
Maps depict predicted hot spots for EID events caused by (a) zoonotic pathogens from wildlife; (b)
|
From page 38... ...
Establishing Causation In order to establish that a pattern of climatic variability or an extreme weather event caused a change in the transmission or geographic range of a particular infectious disease, several requirements must be met. For example, Haines observed, to infer a causal relationship between an El Niño cycle and a given health outcome, three elements are necessary: climate data, preferably local; a plausible biological relationship between a particular disease outcome and climate data; and a relatively long time series (e.g., decades)
|
From page 39... ...
A fourth task was proposed by speaker Douglas MacPherson of McMaster University and Migration Health Consultants, Incorporated: to recognize and address the contribution of human behavior to global climate change and its further effects on infectious disease emergence. In his coauthored contribution to Chapter 4, MacPherson describes the complex, two-way association between climate change and human mobility -- "a determinant of health that is directly linked to globalization of microbial disease threats and risks." Connecting Climate and Migration The immense contribution of human mobility and migration to infectious disease emergence is often illustrated in terms of annual global statistics such as these presented by MacPherson: • 802 million international arrivals (2006)
|
From page 40... ...
in Alaska, WNV in the United States, and bluetongue in northern Europe -- have raised attention regarding the potential effects of climate change on infectious disease emergence and spread. However, as speaker Diarmid Campbell-Lendrum of WHO noted, climate change is expected to exact its most profound toll on the health of the world's poor, through increased rates of malaria, diarrheal diseases, and malnutrition.
|
From page 41... ...
. The NIC has chosen to evaluate the potential impacts of climate change on four essential components of national power: geopolitical power, military power, economic power, and social cohesion.
|
From page 42... ...
Participants placed particular emphasis on the following considerations for studying the influence of climate change on infectious disease emergence: • Developing a greater understanding of the interaction of climate with other major factors in disease emergence and resurgence, such as the globalization of travel and trade, population growth, urbanization, land-use patterns, and habitat destruction; • Establishing long-term monitoring programs to simultaneously track climate and infectious disease dynamics, and optimizing instruments (many of which were designed for other purposes) for use in such programs; • Devising metrics to relate changes in the physical environment to ecological and epidemiological trends and to evaluate potential adaptation and mitigation measures; and • Continuing the development and refinement of predictive models of climate and infectious disease as the basis for early warning and public health response systems, and involving of stakeholders in the operation of such systems.
|
From page 43... ...
Recent Changes Over the last century, global average temperatures and sea levels have risen significantly, while snow cover in the Northern Hemisphere has declined (see Figure SA-17; National Geographic Society, 2007)
|
From page 44... ...
. Present Effects and Future Projections A warmer global climate system accelerates the hydrological cycle, increas ing the likelihood of extreme weather phenomena such as droughts, heavy pre cipitation, heat waves, hurricanes, typhoons, and cyclones (see Figure SA-19; National Geographic Society, 2007)
|
From page 45... ...
with permission from the National Geographic Society. 45 Broadside bitmapped
|
From page 46... ...
global average sea level rise from tide gauge (blue) and satellite (red)
|
From page 47... ...
47 SOURCE: Reprinted from National Geographic Society (2007) with permission from the National Geographic Society.
|
From page 48... ...
2004. Emerging infectious diseases of plants: pathogen pollution, climate change and agrotechnology drivers.
|
From page 49... ...
2000. Emerging infectious diseases of wildlife -- threats to biodiversity and human health.
|
From page 50... ...
2008. Global trends in emerging infectious diseases.
|
From page 51... ...
1996. Global climate change and emerging infectious diseases.
|
From page 52... ...
Emerging Infectious Diseases 11(7)
|
From page 53... ...
2007. Rift Valley fever, http://www.who.int/mediacentre/ factsheets/fs207/en/ (accessed June 19, 2008)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.