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Origin Story

Analysing infectious agents for genetic variation rate allows the disease's history to be reconstructed

17 April 2020

Origin Story

As the coronavirus pandemic progresses, it seems more important than ever to understand how infectious diseases arise and spread through populations. One team of researchers tackled this question for a very different enemy: anthrax, a severe disease affecting many animals, primarily ungulates but also humans, caused by infection with the bacterium Bacillus anthracis. While well-studied in the laboratory, infections in the wild remain poorly understood. In Etosha National Park, Namibia, plains zebra (pictured) are the main host, and transmission often occurs when zebras forage in areas contaminated by infected carcasses. Scientists sampled bacteria from carcasses, measured genetic variation between them and estimated their mutation rate to reconstruct the disease’s history, establishing that small initial populations of bacteria trigger rapid infections. Similar methods have already been used to trace HIV infections, and, with ever-improving sequencing technologies, could also be applied to other bacterial diseases, in wild animals and in humans.

Written by Emmanuelle Briolat

  • Image by W. Ryan Easterday
  • Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Norway and Department of Biological Sciences, University at Albany, State University of New York, Albany, NY, USA
  • Image copyright held by the photographer; image reproduction permitted by PNAS
  • Published in PNAS, February 2020

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BPoD stands for Biomedical Picture of the Day. Managed by the MRC Laboratory of Medical Sciences until Jul 2023, it is now run independently by a dedicated team of scientists and writers. The website aims to engage everyone, young and old, in the wonders of biology, and its influence on medicine. The ever-growing archive of more than 4000 research images documents over a decade of progress. Explore the collection and see what you discover. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.

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