According to scientists from Australia, Laos and South Africa who conducted the study, the cumulative effect of large dams on malaria has not been known despite the construction of many dams on the continent.
Therefore, they mapped the distribution of 1,268 large existing dams and 78 large planned dams in relation to malaria transmission across all countries in Sub-Saharan Africa.
“Given the likelihood of more dam construction in Africa in the coming years, it is increasingly important that adverse malaria impacts of dams are addressed.”
Jonathan Lautze, International Water Management Institute, Pretoria, South Africa
Jonathan Lautze, a co-author of the study and a researcher at the International Water Management Institute Southern Africa office in Pretoria, South Africa, says they collected and quantified the cumulative malaria impact of large dams in Sub-Saharan Africa, documented the relative effect of dams in zones of different stability of malaria transmission and determined the distribution of dams in relation to these zones.
Lautze explains that the study shows large dams are contributing substantially to malaria in the region, and that the resulting aggregate number of malaria cases of more than a million requires greater focus.
“Given the likelihood of more dam construction in Africa in the coming years, it is increasingly important that adverse malaria impacts of dams are addressed,” he says, noting that the study provides a strong rationale for greater emphasis on mitigating dam-associated malaria.
The study’s findings could help development agencies and health specialists who may wish to prioritise malaria control efforts, he adds, noting that some revenue from hydropower-related dams could be redirected toward local mitigation efforts.
While the number of existing and planned dams for which locations could be found was below the known total of each, the set of existing and planned dams mapped for this study is the most extensive yet used in an analysis of the malaria impacts of dams in Sub-Saharan Africa, according to the study which was published in the Malaria Journal last month (4 September).
Alex Awiti, an ecosystems ecology expert at the Kenya-based Aga Khan University, says stagnant water of any kind, in puddles or lagoons provides suitable habitat for mosquitoes.
“What is new is that this study now shows the scale or magnitude of the problem,” he tells SciDev.Net.
Governments, he says, have no excuse for not providing bednets, undertaking regular indoor spraying and ensuring that test kits are available at local clinics or pharmacy outlets to ensure timely diagnoses and treatment. Awiti says this study presents evidence at scale of the potential trade-off between the positive economic benefits of dams and human health consequences.
“We are faced with trade-offs all the time. Nevertheless, the choices are clear. We must think about approaches to control malaria transmission whenever large dam projects are implemented,” Awiti adds.
This article has been produced by SciDev.Net's Sub-Saharan Africa desk.