The impact of changing climate on vector-borne diseases

TDR news item
6 August 2014

One of the study sites – a Maasai community in Simanjiro District, Tanzania
Credit: Paul Gwakisa, NMAIST, Arusha, Tanzania

East of Eldoret, along the Rift Valley in Kenya, is Baringo county, a dryland area where slight changes in climate exacerbate poverty. Poor communities reliant on crops and livestock can see their livelihoods and food security wrecked by unexpected weather patterns. Rains may increase the numbers of mosquitoes that carry malaria and increase the incidence of Rift Valley fever that can make both people and cattle very sick.

That's why a team of scientists, led by Professor Benson Estambale of Jaramogi Oginga Odinga University of Science and Technology in Kenya, are here to study precisely how climate changes affect the incidence of these diseases and to develop early warning systems that will predict outbreaks.

“We are wondering what sparks outbreaks of malaria and Rift Valley fever here. This is a major issue to us and we take it very seriously, “ he said. Estambale's research forms part of a major research initiative from TDR to better understand the changing climate and its effects on vector-borne diseases in Africa.

Five major African research projects supported by TDR and its funding partner, Canada’s International Development Research Centre (IDRC) are located in the United Republic of Tanzania, Botswana, South Africa, Zimbabwe, Kenya, Mauritania and Côte d’Ivoire to study malaria, human African trypanosomiasis, Rift Valley fever and schistosomiasis. They are looking at changes in land use, dams, vector distribution and water availability, and how these changes affect diseases experienced by a range of communities.

Bernadette Ramirez at a site visit to a Maasai community in Simanjiro District, Tanzania
Credit: Paul Gwakisa, NMAIST, Arusha, Tanzania

This research is crucial because, although scientists broadly agree that climate change can potentially affect vector-borne diseases, the exact effects are still unclear. That's especially true in Africa, where research has been limited. Dr Bernadette Ramirez, from TDR's new research unit on Vectors, Environment and Society (VES), who works with the research groups, says evidence must be gathered to correctly inform strategies for community adaptation to climate change.

“Changes in climate may likely affect the transmission of vector borne diseases,” she explained. “It's one thing to think that there is risk and it's a reasonable [assumption] but it is also important to provide the evidence and to develop adaptation approaches to increase community resilience against these diseases.”

That's why the projects combine so many disciplines ̶ from entomology, malacology and parasitology to epidemiology, social sciences, climatology/meteorology and indigenous knowledge, too. “We have to look at data in an integrated way to understand how climate has changed the ecology and the mosquito vector itself, and how these changes may affect disease transmission in the communities, “ she said.

Take research led by Professor Moses Chimbari, dean of research at the University of KwaZulu-Natal in South Africa. His group is assessing malaria and schistosomiasis changes in 3 sites within southern Africa.

Researchers discussing a tsetse fly trap in Tanzania
Credit: Paul Gwakisa, NMAIST, Arusha, Tanzania

Part of the work will focus on women around the Okavanga Delta in Botswana. Because they are responsible for basket fishing and collecting water, they are more exposed than men to water bodies where mosquitos breed. “We need to develop a proper vulnerability index so we can say one community is more vulnerable than the other,” said Chimbari. ”Because if I am a government minister, I will want to put my resources where it is going to make the biggest impact.”

“We anticipate that the research results will have the potential to enhance impacts on national research and policy agendas,” said Thierry Baldet, senior programme specialist at IDRC. “Over the longer term, the initiative will contribute to a more effective use of investments from African governments and donors to respond to emerging health threats linked to climatic change.”

TDR has long been at the heart of efforts to effect change – together with colleagues from WHO’s African regional office, it supports the implementation of the ground-breaking 2008 Libreville Declaration on Health and Environment, in which 52 African governments agreed to prepare for the health-related consequences of climate change. Today African policy-makers are creating national adaptation plans because of that agreement.

TDR is also part of Clim-Health Africa, a group of 14 research institutions from across the globe dedicated to developing scientific skills and tools, such as early warning and response systems, that could be used by African countries to monitor and cope with the effects of climate change.

Building capacity

Johannes Sommerfeld, TDR, at the July 2014 workshop in Tanzania
Credit: Paul Gwakisa, NMAIST, Arusha, Tanzania

The TDR-IDRC research initiative is not just about doing research, but also about building capacity for an integrated and multi-disciplinary approach to addressing population health vulnerabilities to vector-borne diseases. Numerous workshops are planned for the duration of the project. Just recently, the researchers met in Arusha, the United Republic of Tanzania, for sessions on vulnerability assessment, working with communities, economic evaluation of adaptation costs, managing data on climate and environment, and how to ensure research results are used for policy change.

A workshop participant wrote in the evaluation, “Overall, the workshop was a big success. I appreciate the opportunity for our research team to interact with the other teams and facilitators.”

The researchers are developing a knowledge-sharing platform, which will be used for further training and capacity building. The scientists were hosted by the Nelson Mandela African Institution of Science and Technology.

For more information, contact:

Bernadette Ramirez (