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

Emmanuelle Briolat

Writer

A researcher specialising in visual signals in Lepidoptera, camouflage and the effects of light pollution, Emmanuelle’s writing covers a range of topics, from biomedical research to children’s books about moth defences.

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• 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