Değişen İklimde Sağlık Pişmanlıklarını Azaltmak

Özet (abstract)

Acknowledging that climate change is a common concern of humankind, Parties should, when taking action to address climate change, respect, promote and consider their respective obligations on … the right to health — Paris Agreement under the United Nations Framework Convention on Climate Change, signed by 195 countries on 12 December 2015 There is now overwhelming scientific consensus that climate change is occurring, and with it comes a range of social issues—unprecedented in scale—that must be addressed. Key among these issues are the health consequences of climate change. The most recent report from the Intergovernmental Panel on Climate Change states with “very high confidence” that “the health of human populations is sensitive to shifts in weather patterns and other aspects of climate change” due to direct effects—such as changes in temperature and precipitation or occurrence of heat waves, floods, droughts, and fires—as well as indirect effects—through crop failures, shifting patterns of disease vectors, or displacement of populations [1]. A recent World Health Organization report suggests that globally climate change could cause an additional 250 000 additional deaths per year between 2030 and 2050, not taking into account factors such as the effects of economic damage, major heat wave events, river flooding, water scarcity, or human conflict. A large portion of these estimated additional deaths are associated with infectious diseases—specifically malaria (60 000 annual deaths) and diarrhea (48 000 annual deaths) [2]. Many infectious diseases are sensitive to climate, especially those caused by pathogens that survive in the environment or are transmitted by insect vectors. There are established positive associations between rates of many diarrheal diseases and ambient temperature, heavy rainfall, and flooding [3]. For vector-borne diseases, higher temperatures can increase vector biting rate and replication of the pathogen within the vector [2], although vectorial capacity only increases up to a certain optimum, beyond which temperatures limit mosquito survival [4, 5]. Humidity can affect diseases transmitted by vectors without aquatic stages (ticks and sandflies), and precipitation strongly influences population sizes of vectors with aquatic developmental stages (including mosquitoes) [6]. Range expansion has already been observed for several vector-borne pathogens along the edges of their present distributions, for example, with Lyme disease in Canada [7] and tick-borne encephalitis in Sweden [8] and Slovakia [9]. A recent comparison of multiple malaria model estimates indicated an overall global net increase in climate suitability, especially in tropical highland regions, and a net increase in the population at risk, albeit with large uncertainties [10]. At the same time, transmission is expected to decrease in lowland regions of Africa [11]. Results of various models of future dengue transmission vary with regard to specific geographic areas where expansion or intensification is likely to occur, but all project increases in the overall global extent of dengue transmission [12]. Although rates have fallen in the past decade due to public health programs, in 2013, diarrheal diseases were still responsible for approximately 1.3 million deaths and malaria for approximately 850 000 deaths globally [13]. With such high baseline rates, even relatively small percentage increases that may come with future climate regimes can have an immense public health impact, threatening the recent progress that has been made in combating these diseases. For example, in a recent paper we found an 8% (95% confidence interval, 5%–11%) increase in diarrheagenic E. coli incidence for a 1°C increase in mean monthly temperature. Applying our models to just 1 country—Bangladesh—for just 1 specific pathogen—enterotoxigenic Escherichia coli—we estimated 800 000 additional annual cases in the near term (2016–2035), and 2.2 million additional annual cases by the end of the century [14], for a pathogen whose case rate is associated with an increased risk of case death [15]. Although there is a high degree of uncertainty in these estimates, this example illustrates the potential multiplicative effect of increasing global temperatures in regions with high baseline prevalence. Despite what we know about sensitivities of infectious diseases to climate, the relationships between climate and pathogens are complex and nonlinear, making future predictions a challenge. For diarrheal diseases, the direction of temperature-disease relationships varies by causative agent, with bacterial, protozoan, and viral diarrhea pathogens sometimes showing opposite patterns. For rainfall the effects are also often nonlinear and dependent on preceding conditions [3]. For vector-borne diseases, the complexities of vector life cycles and ecology make the effects of climate change difficult to predict, and likely regionally variable [16, 17]. Although many vector-borne diseases have appeared in new regions in the past 2 decades and endemic diseases have increased in incidence, factors such as trade and travel, land use, populations of animal hosts, and socioeconomic conditions are predominant factors in driving these changes [16–18]. Policy makers will convene this November in Morocco for the 22nd Conference of Parties, to follow up the historic Paris Agreement of 2015, an unprecedented and far-reaching global climate agreement adopted by 195 countries that sets ambitious aims to curb greenhouse gas emissions to keep global warming below 2°C. On the agenda for this and future Conference of Parties meetings will be planning adaptation measures that will protect the “right to health” acknowledged by the Paris Agreement. Although there will always be uncertainty in our abilities to predict how climate change drives infectious disease incidence, emergence, and spread, the magnitude of potential impact provides sufficient impetus to reinforce proven public health measures that we know to be effective in targeting infectious diseases. One notable conclusion of work to date on climate and health is that we already have many tools available to adapt to climate change. The most recent Intergovernmental Panel on Climate Change report states with very high confidence that “The most effective measures to reduce vulnerability in the near term are programs that implement and improve basic public health measures such as provision of clean water and sanitation, secure essential health care including vaccination and child health services, increase capacity for disaster preparedness and response, and alleviate poverty.” Similarly, according to the World Health Organization, “strengthening of current disease control efforts to bring down current disease rates and manage short-term climate risks” is the most pressing need for building resilience to long-term climate change [6]. In other words, if diseases that we already have methods to control might increase as a function of climate change, then a redoubling of efforts to address these diseases could—and should—be considered a form of climate change adaptation. Investing in the expansion and/or maintenance of existing public health approaches represents a no-regrets strategy that provides benefits under both current and potential future climatic conditions [19] and probably has other economic, environmental or social cobenefits while increasing resilience to climate change impacts. Drinking water treatment accounted for more than half the reduction in total mortality and up to three-quarters of the reduction in infant mortality during the late 19th and early 20th centuries in the United States [20], and interventions to improve drinking water and sanitation are effective in reducing the incidence of diarrhea in low- and middle-income countries [21–23]. Similarly, for malaria the 12% reduction in cases and 48% reduction in deaths over the African continent since 2000 is attributable to improved vector control and development of rapid diagnostic tests [18]. There is ample work to do to develop new strategies to adapt to the specific infectious disease threats posed by climate change, such as developing enhanced surveillance programs and early warning systems for extreme events. We must seek out these creative solutions to combat the particular threats of climate change. At the same time, we should not forget the many off-the-shelf tools already at our disposal—such as water and sanitation infrastructure, mosquito abatement, and sustained vaccination campaigns—and use new research to apply these existing strategies more effectively. Predictive models on how and where climate is expected to affect infectious diseases can be helpful in prioritizing different types of prevention efforts. For example, models of malaria transmission in Africa suggest an increase in the overall area suitable for malaria transmission, but a net decrease in the most suitable area, as well as shifts in where these areas occur on the continent [24]. This information can help guide disease control measures, because the types of interventions needed in areas suitable for endemic year-round transmission—such as distribution of bed nets to prevent sustained transmission—differ from those most appropriate for areas with epidemic or seasonal transmission—such as targeted spraying and surveillance for drug resistance that can stem from sporadic use of prophylaxis. Similarly, for water-borne diseases, we can use information on the expected changes in prevalence of diarrhea of viral versus bacterial etiology to prioritize investments in vaccination versus water, sanitation, and hygiene campaigns in different locations or at different times of the year. In the long run, redoubling investments in mundane public health measures, and using new research to target those investments most effectively, could prove even more essential than developing new climate-specific solutions. This strategy will help us get ahead of the curve toward combating the additional burden of infectious diseases that climate change brings, while also protecting the substantial advances in combating these diseases that we have made in the past decades. Disclaimer. The content is solely the responsibility of the author and does not necessarily represent the official views of the National Institutes of Health (NIH). Financial support. This work was supported by the National Institute for Allergy and Infectious Diseases, NIH (grant 1K01AI103544 to K. L.). Potential conflict of interest. Author certifies no potential conflicts of interest. The author has submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Yazarların özeti; kaynağından alınmıştır. The Journal of Infectious Diseases, 2016 · DOI ↗