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Climate change and African trypanosomiasis vector populations in Zimbabwe's Zambezi Valley: A mathematical modelling study

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Lord, Jennifer, Hargrove, John W, Torr, Steve ORCID: https://orcid.org/0000-0001-9550-4030 and Vale, Glyn A (2018) 'Climate change and African trypanosomiasis vector populations in Zimbabwe's Zambezi Valley: A mathematical modelling study'. PLoS Medicine, Vol 15, Issue 10, e1002675.

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Abstract

Background
Quantifying the effects of climate change on the entomological and epidemiological components of vector-borne diseases is an essential part of climate change research, but evidence for such effects remains scant, and predictions rely largely on extrapolation of statistical correlations. We aimed to develop a mechanistic model to test whether recent increases in temperature in the Mana Pools National Park of the Zambezi Valley of Zimbabwe could account for the simultaneous decline of tsetse flies, the vectors of human and animal trypanosomiasis.

Methods and findings
The model we developed incorporates the effects of temperature on mortality, larviposition, and emergence rates and is fitted to a 27-year time series of tsetse caught from cattle. These catches declined from an average of c. 50 flies per animal per afternoon in 1990 to c. 0.1 in 2017. Since 1975, mean daily temperatures have risen by c. 0.9°C and temperatures in the hottest month of November by c. 2°C. Although our model provided a good fit to the data, it cannot predict whether or when extinction will occur.

Conclusions
The model suggests that the increase in temperature may explain the observed collapse in tsetse abundance and provides a first step in linking temperature to trypanosomiasis risk. If the effect at Mana Pools extends across the whole of the Zambezi Valley, then transmission of trypanosomes is likely to have been greatly reduced in this warm low-lying region. Conversely, rising temperatures may have made some higher, cooler, parts of Zimbabwe more suitable for tsetse and led to the emergence of new disease foci.

Item Type: Article
Subjects: QX Parasitology > Insects. Other Parasites > QX 650 Insect vectors
WA Public Health > WA 30 Socioeconomic factors in public health (General)
WA Public Health > Health Problems of Special Population Groups > WA 395 Health in developing countries
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 705 Trypanosomiasis
Faculty: Department: Biological Sciences > Vector Biology Department
Digital Object Identifer (DOI): https://doi.org/10.1371/journal.pmed.1002675
Depositing User: Stacy Murtagh
Date Deposited: 24 Oct 2018 14:28
Last Modified: 25 Oct 2018 11:10
URI: http://archive.lstmed.ac.uk/id/eprint/9502

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