African Dams linked to over one million malaria cases

Dam projects need to consider better disease control measures

Over one million people in sub-Saharan Africa will contract malaria in 2015 because they live near a large dam, according to a new study. For the first time, data was correlated with the location of large dams with incidence of malaria and quantified impacts across the region.

The study finds that construction of an expected 78 major new dams in sub-Saharan Africa over the next few years will lead to an additional 56,000 malaria cases annually

The research, published in this month’s Malaria Journal, has major implications for new dam projects and how health impacts should be assessed prior to construction. Encouraged by the increased volume of international aid for water resource development, sub-Saharan Africa has, in recent years, experienced a new era of large dam construction.

“Dams are at the center of much development planning in Africa. While dams clearly bring many benefits—contributing to economic growth, poverty alleviation and food security—adverse malaria impacts need to be addressed or they will undermine the sustainability of Africa’s drive for development,” said biologist Solomon Kibret of the University of New England in Australia, the paper’s lead author. Undertaken as part of the CGIAR Research Program, a research consortium on water, land and ecosystems, the study looked at 1,268 dams in sub-Saharan Africa. Of these, just under two-thirds, or 723, are located in areas with malaria incidences. A total of 15 million people living within 5 km of dam reservoirs are at risk.

“Our study showed that the population at risk of malaria around dams is at least four times greater than previously estimated,” said Kibret, noting that the authors were conservative in all their analyses. Previous research has identified increased malarial incidence near major sub-Saharan dams such as the Akosombo Dam in Ghana, the Koka Dam in Ethiopia and the Kamburu Dam in Kenya.

Malaria transmitted by the Anopheles mosquito, needs slow-moving or stagnant water to breed. Dam reservoirs, particularly shallow puddles that often form along shorelines, provide a perfect environment for the insects to multiply. Thus dam construction can intensify transmission and shift patterns of malaria infection.

Many African countries are planning new dams to help drive economic growth and increase water security. But the researchers warn that building new dams has potential costs as well as benefits. Co-author Matthew McCartney of International Water Management Institute (IWMI) said, “Dams are an important option for governments anxious to develop but it is unethical that people living close to them pay the price of that development”

The authors recommend that dam reservoirs could 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.

Dam developers should consider increasing investment in integrated malaria intervention programs

Other environmental controls, such as introducing fish that eat mosquito larva in dam reservoirs, could also help reduce malaria cases in some instances. “Environmental Impact Assessments for dams recognizes malaria as a concern, and areas around dams are frequently earmarked for intensive control efforts” said co-author Jonathan Lautze, IWMI’s Pretoria office. Malaria must be addressed while planning, designing and operating African dams.

Featured photo credits: Blyde River Dam, South Africa/Neville Nel/Flickr photos/ reposduced under Creative Commons Attribution-Non-Commercial-Share Alike 3.0 license