What is it about?
Rodents host many zoonotic pathogens that are harmful for human health. To understand and mitigate this risk, it is therefore helpful to understand how rodent populations are regulated and how, in turn, human disease risk might be shaped. This paper explores this using three decades of data on the multimammate mouse, which carries the virus responsible for outbreaks of Lassa fever in human populations in West Africa.
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Photo by NOAA on Unsplash
Why is it important?
Our research has three major findings. 1) The number and timing of young born into the population is a very climate-sensitive process. We found that annual births of rodents follow the seasonal rains, likely because rainfall stimulates the growth of vegetation on which rodents depend. This finding has implications for how rodent populations might be affected by a changing climate, as some areas are expected to become drier and others wetter. 2) These births drive pathogen transmission within the rodent population, with "vertical" transmission (a disease passing from a mother to her offspring) playing a more significant role than previously thought. We identify this as a key mechanism of transmission, suggesting that rodent fertility management might be an effective method of rodent disease control. 3) These seasonal births explain rodent disease outbreaks and, we find, seem to explain the timing of human zoonotic disease risk. We found our predictions of when the number of infected rodents peaked was at a similar time to that of human cases of Lassa fever in West Africa. This rodent-borne disease causes annual outbreaks of severe illness in humans, sometimes leading to death. So, linking rodent population changes to the timing of human disease outbreaks is an important step towards better disease prediction and prevention.
Perspectives
This research demonstrates something that should be intuitive: when trying to understand human diseases that come from animals, we need to understand what’s happening in the animal population. In other words, you can’t take the ecology out of zoonotic diseases and still expect to understand the whole picture. This paper wouldn’t have been possible without the tireless work of many people trapping and tagging rodents in Morogoro, Tanzania, every month for over the past three decades. A truly gargantuan effort. In an increasingly digital world, it is essential that long-term studies like these continue to be funded. My sincere thanks go to co-authors on this paper who are involved in this long-term study and who kindly provided the data before it became open access: Dr. Joachim Mariën, Dr. Lucinda Kirkpatrick, and Prof. Herwig Leirs.
Gregory Milne
Natural History Museum, London
Read the Original
This page is a summary of: Climate-driven host ecology as a framework for zoonotic disease risk: Understanding transferability across arenavirus systems, Proceedings of the National Academy of Sciences, September 2026, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2625913123.
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