Nana Kofi Acquah/IWMI.

Press release: Climate change likely to vastly expand malaria risk from African dams

New study urges dam projects to diversify disease control measures

PRETORIA, SOUTH AFRICA (5th September 2016) — New research indicates that the number of people at risk of malaria around dams, and associated reservoirs, in sub-Saharan Africa will nearly double to around 25 million by 2080. And, in the absence of an increase in preventative measures, the number of actual malaria cases associated with dams could increase threefold to nearly 3 million a year over the same period.     

The research, published today in this month’s issue of Malaria Journal, has major implications for programs such as the Roll Back Malaria Partnership of the World Health Organization, which seeks to reduce the global malaria burden (the majority of which is in Africa) by 90% by 2030. In recent years significant advances have been made. It is estimated that in sub-Saharan Africa malaria associated mortality has been reduced by 45%, in part as a consequence of anti-malaria programs and in part as a consequence of economic development. However, this study highlights that if advances are to be continued and future targets achieved, there is a critical need to direct attention and resources toward applying comprehensive, sustainable solutions for managing human health impacts in the vicinity of both existing and new large dams.

In recent years the sub-Saharan Africa has embarked on a new era of dam construction to promote economic growth, alleviate poverty and ensure food security. Many African countries are planning new dams to help drive economic growth and increase water security. Improved water storage for growing populations, irrigation and hydropower generation are indeed badly needed for a fast developing continent. But the researchers warn that without a much greater effort at disease mitigation, building new dams will likely add to the malaria burden.   

“While dams clearly bring many benefits, the present study confirmed that the role of climate change on malaria around dams will fundamentally alter the current impact of dams on malaria” said biologist Solomon Kibret of the University of California in US, the paper’s lead author. “Dams’ future impacts on malaria transmission in the context of climate and demographic change are poorly understood and seldom investigated. Accurately predicting the impacts of such changes is critical to planning effective disease control. Given the impending magnification in the threat of mosquito borne infections, there is urgent need for pro-active measures that mitigate the health risks of today and tomorrow.”

Undertaken as part of the CGIAR Research Program on Water, Land and Ecosystems, the current study built on research published last year that identified that the cumulative impact of large dams on malaria today, under current conditions, is just over 1 million cases per year in Africa. The new study advanced this research by determining the future malaria transmission, resulting from the possible implications of climate change and population rise. The study found that more than half of dams currently located in areas without malaria will transition into zones of malaria transmission thanks to climate change. In such regions, found predominantly in the East African highlands and southern Africa, the impacts of dams may be particularly brutal due to lower immunity among populations that have traditionally not had to deal with the disease. 

“Our study showed that the population at risk of malaria around dams may increase by about two-thirds by the 2050s and double by the 2080s. What’s more, these numbers are conservative since our study had to exclude more than 800 dams that are not mapped and because dams that are planned to be built in the future were not included” said Matthew McCartney.

Greater efforts to control malaria could curb a considerable amount of the potential malaria increase. However, it is important to recognize that, as last year’s study highlighted, dams intensify malaria transmission even where conventional control measures, such as the use of impregnated bednets and insecticides, are applied. It is becoming increasingly clear that robust and sustainable solutions to malaria control around dams will require a diversification in methods employed.

“It is common knowledge that strategies that best respond to risk are those that diversify rather than concentrate resources. As such, increased risk due to climate change will no doubt render current approaches to malaria control around dams – which exclude viable options from their arsenal – further obsolete. The time for putting on the table currently-sidelined measures for malaria control around reservoirs, such as water-level management, is long overdue,” says Jonathan Lautze, senior researcher at IWMI-southern Africa.

The bottom line is that non-traditional measures need to be considered. Dam reservoirs can be more effectively designed and managed to reduce mosquito breeding. For instance, one option is to adopt operating schedules that, at critical times, dry out shoreline areas where mosquitoes tend to breed. Other environmental controls, such as introducing fish that eat mosquito larva in dam reservoirs, could also help reduce malaria cases in some instances. The authors contend that such approaches, used in conjunction with the traditional measures, such as bed net distribution, are likely to be far more suited to cope with the risks brought by climate change.

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The International Water Management Institute (IWMI) is a non-profit, scientific research organization focusing on the sustainable use of water and land resources in developing countries. IWMI is a member of the CGIAR Consortium. CGIAR is a global partnership that unites organizations engaged in research for a food-secure future. It leads the CGIAR Research Program on Water, Land and Ecosystems which examines how we can intensify agriculture while still protecting the environment and lifting millions of farm families out of poverty.

The CGIAR Research Program on Water, Land and Ecosystems (WLE) combines the resources of 11 CGIAR Centers, the Food and Agriculture Organization of the United Nations (FAO) and numerous national, regional and international partners to provide an integrated approach to natural resource management research. WLE promotes a new approach to sustainable intensification in which a healthy functioning ecosystem is seen as a perquisite to agricultural development, resilience of food systems and well-being. This program is led by the International Water Management Institute (IWMI), a member of the CGIAR Consortium and is supported by CGIAR, a global research partnership for a food-secure future.

Once published, the full research can be accessed at: http://malariajournal.biomedcentral.com/articles/10.1186/s12936-016-1498-9