Projected Delays in Reducing Waterborne and Water-Related Infectious Diseases in China Under Climate Change

by Allison Hu

In 2010, infectious disease due to unsafe water, sanitation, and hygiene (WSH) were estimated to be responsible for 337,000 deaths globally and the loss of over 21 million disability-adjusted life years (DALYs) (Hodges et al. 2014). These WSH-attributable diseases include soil-transmitted helminth infections, schistosomiasis, diarrhoeal diseases, and vector-borne diseases such as malaria, dengue fever, and Japanese encephalitis. In China, the WSH-attributable disease burden is concentrated in low-income areas and in young children. Cases not leading to morbidity and mortality, these diseases can causes malnutrition, stunting, impaired school performance, immunodeficiency, and impaired cognitive functioning which can hinder economic growth and development at a population level (Hodges et al.). Furthermore, there are studies associating certain diseases with key environmental variables that are responsive to changes in climate, such as temperature, precipitation, and relative humidity. Temperatures changes can influence the replication rate and survival of pathogens and vectors in the environment and impact transmission. Heavy precipitation can overwhelm existing water and sanitation systems, therefore mobilizing pathogens, while drought conditions can increase pathogen exposure by limiting the water available for hygiene and forcing populations to resort to the use of contaminated water supplies.

Although China has taken tremendous strides in reducing these WSH-attributable diseases through decade-long improvements in water supply and sanitation, with the Millennium Development Goal (MDG) for drinking water met in 2009, the MDG for water sanitation has been more difficult to attain and is particularly more vulnerable to risks associated with the impacts of climate change on water supply and quality. China is projected to experience large changes in its climate this century – an increase of 1.8–5.8 ◦C in temperature compared to the average global temperature increases of 0.3–4.8 ◦C.

Because certain infectious diseases are sensitive to changes in both climate and WSH conditions, Hodges et al. projected impacts of climate change on WSH-attributable diseases in China in 2020 and 2030 by coupling estimates of the temperature sensitivity of diarrhoeal diseases and three vector-borne diseases, temperature projections from global climate models, WSH-infrastructure development scenarios, and projected demographic changes. This study is the first assessment of the impact of climate change on WSH-attributable diseases across China.

Although China’s demographic and epidemiologic transitions, as well as changes to water and sanitation infrastructure, are expected to rapidly decrease the burden of infectious disease, analysis by Hodges et al. demonstrate that climate change will blunt this progress, even while controlling for demographic changes, infrastructure development and urbanization.

In the presence of climate change, China loses on the order of 1–2 years of progress in reducing the burden of diarrhoeal and other WSH-attributable diseases; an additional 15–21 months of continued infrastructure investment, urbanization and demographic shifts will be required to achieve the decreased disease burden projected in the absence of climate change. This projected development delay can be interpreted as the additional years of continued investment in infrastructure and personnel required in the presence of climate change to achieve the disease burden anticipated without climate change. Likewise, results further demonstrated that assuming high emissions (representative concentration pathway (RCP) 8.5) and a maintenance development path, this development delay increases to over 5 years by 2030. Under the most aggressive water and sanitation development path, the development delay by 2030 is 13 months under RCP 2.6 and 18 months under RCP 8.5. By 2030, climate change is projected to delay China’s rapid progress towards reducing WSH-attributable infectious disease burden by 8–85 months.

This development delay summarizes the adverse impact of climate change on WSH-attributable infectious diseases in China, and can be used in other settings where a significant health burden may accompany future changes in climate even as the total burden of disease falls owing to non-climate reasons. Furthermore, this present analysis indicates the need to acknowledge the net delay in development that climate change driven by greenhouse gas emissions will impose. The impact of climate change on WSH-attributable disease most likely extends beyond the burden of disease discussed by Hodges et al., for the study focuses on the impacts associated with climate change and does not incorporate the development delays imposed by climate change due to greenhouse gas emissions. Therefore, it is probable that the true development delay imposed by climate change on China is much higher than stated in this study.

Hodges, M., Belle, J. H., Carlton, E. J., Liang, S., Li, H., Luo, W., Freeman, M. C., Liu, Y., Gao, Y., Hess, J. J., Remais, J. V., 2014. Delays in reducing waterborne and water-related infectious diseases in China under climate change. Nature climate change, 1109–1115.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hodges, M., Belle, J. H., Carlton, E. J., Liang, S., Li, H., Luo, W., Freeman, M. C., Liu, Y., Gao, Y., Hess, J. J., Remais, J. V., 2014. Delays in reducing waterborne and water-related infectious diseases in China under climate change. Nature climate change, 1109–1115.

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