Science for society
Climate change might have an impact on diseases carried by insects, which in Africa could have serious consequences for the prevalence of sleeping sickness and malaria.
Global warming could influence the distribution ranges and activities of the species of tsetse fly and mosquito that act as vectors for the diseases, which might expose more people to harm.
The Centre for Invasion Biology (C·I·B) is working to address this problem. Its scientists are conducting research into the effects of climate change on the vectors of sleeping sickness and malaria, and how this might compromise human development goals.
“The findings could have major implications because these two diseases have major impacts on people’s livelihoods in Africa,” says Dr Elrike Marais, a research and project manager at the C·I·B.
This work forms part of an initiative entitled “Invasion Biology in Support of Sustainability During Times of Change”.
C·I·B researchers take aspects of theoretical modelling, ecology, physiology and molecular biology of invasive and non-invasive species into account in studying biological invasions, biodiversity and the functioning of ecosystems.
The Tsetse Fly
Six of the more than 30 species of tsetse fly found in sub-Saharan Africa are carriers of the parasite that causes sleeping sickness. The fly’s bite can transmit the disease, which could be fatal if not treated.
Sixty million people living in mainly rural parts of West, Central and East Africa are at risk of contracting sleeping sickness. And the variant of the disease found in cattle, nagana, can devastate herds and has made areas of the African countryside unsuitable for livestock farming.
Tsetse flies have a limited ability to adapt to climate stress. They seem unable to stand temperatures higher than 44 degrees Celsius, which means that rising global temperatures might actually reduce their distribution range. However, it could drive them further south to cooler parts, for instance, Southern Africa.
In addition, warmer temperatures could boost the metabolic rate of tsetse flies and increase their need for more frequent blood meals. Current data puts the chances of humans contracting sleeping sickness from a tsetse fly as one in every 20 bites.
The C·I·B is developing a sleeping sickness risk map, which would identify areas most prone to sleeping sickness.
Malaria
Malaria is one of the leading causes of sickness and death in the developing world. According to the World Health Organisation, the disease kills more than one million children each year in Africa alone.
Both the parasite that causes malaria and the species of mosquito that carry it are sensitive to changes in temperature and precipitation. Understanding future environmental change has so far been most significantly investigated for East Africa, but Southern Africa is also at risk. The C·I·B is focusing on this region, but the modelling approaches being developed are of international interest.
Excellence and relevance
The C·I·B was established under the Centres of Excellence Programme of the government’s Department of Science and Technology (DST) and the National Research Foundation (NRF). Its hub is at Stellenbosch, and it has a network of researchers, associates and students at a range of institutions throughout the country.
The principal aims of the Centre’s work are to reduce the rates and impacts of biological invasions by furthering scientific understanding and predictive capability, and by developing research capacity.
“Invasive species cost the planet about 5% of its gross domestic product a year. We look at why species are moved around the world, why some become invasive, how they can be stopped and what can be done to minimise the effect they have,” says Prof Steven Chown, C·I·B Director.