Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology

Abstract

Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and animals, was recently identified as one of the 12 infectious diseases likely to spread owing to climate change. We combine a variety of direct effects of temperature on vector ecology, vector biology and vector -parasite interactions via a disease transmission model and extrapolate the potential compounding effects of projected warming on the epidemiology of African trypanosomiasis. The model predicts that epidemics can occur when mean temperatures are between 20.78C and 26.18C. Our model does not predict a large-range expansion, but rather a large shift of up to 60 per cent in the geographical extent of the range. The model also predicts that 46-77 million additional people may be at risk of exposure by 2090. Future research could expand our analysis to include other environmental factors that influence tsetse populations and disease transmission such as humidity, as well as changes to human, livestock and wildlife distributions. The modelling approach presented here provides a framework for using the climate-sensitive aspects of vector and pathogen biology to predict changes in disease prevalence and risk owing to climate change.

Molecular Identification of Trypanosome Species in Cattle of the Mikumi Human/Livestock/Wildlife Interface Areas, Tanzania

“…Climatic and ecological changes [7,18], pastoralism and rapidly increasing human population invading wilderness areas [10,19] also influence infection rates.…”

Climate change, cattle, and the challenge of sustainability in a telecoupled system in Africa

“…Recent work has shown that increasing temperatures during the next few decades will substantially reduce the geographic range of one species of the trypanosome parasite in Mozambique ( Fig. 1; Moore et al 2012). Assuming similar range contractions for other Trypanosoma species, bovine trypanosomosis would become less common and cattle production could potentially increase in the country in the future.…”

“…These unique conditions therefore create a telecoupled system among international importers and exporters of livestock products. However, because of a changing climate, temperatures are expected to rise to levels that are harmful to tsetse reproduction and survival as well as pathogen development (Hargrove 2004, Moore et al 2012. Recent work has shown that increasing temperatures during the next few decades will substantially reduce the geographic range of one species of the trypanosome parasite in Mozambique ( Fig.…”

“…First, we must identify key properties of the systems themselves, primarily South Africa, Mozambique, and neighboring countries. Moore et al (2012). It shows the suitable geographical range for Trypanosoma brucei rhodesiense (assuming presence of their vector, tsetse flies) in 2055.…”

Health and climate change: policy responses to protect public health

“…160 The geographical distribution of African trypanosomiasis is predicted to shift due to temperature changes induced by climate change. 161 Biodiversity loss may to lead to an increase in the transmission of infectious diseases such as Lyme disease, schistosomiasis, Hantavirus and West Nile virus. 162 Infectious disease risks are dynamic and subject to multiple and complex drivers.…”