Mongoose in the City: How Landscape Can Affect Disease Transmission in Botswana

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Under a concrete culvert on the outskirts of a town in Botswana, a group of banded mongooses prepare to leave their den. The cat-sized animals move from the shade into the light, scanning the area for signs of danger and for opportunities to find something to eat in an increasingly crowded neighborhood.

Unknowingly, the genetics of the members of this troop – and others like them – provide researchers at the College of Natural Resources and Environment with a new understanding of how and why animal behavior changes in the vicinity of human development, and how that change is changing Can affect infectious disease spread.

The researchers used genetic tools to identify changes in the movement behavior of mongooses living in urban centers and natural areas, and gained important insights into how disease transmission in wild animals in complex landscapes can be better modeled. The results of their study, funded by a grant from the National Science Foundation’s Ecology and Evolution of Infectious Diseases program, were published in the journal Ecology and evolution.

“The question has always been how we can predict what will happen when an infectious disease emerges,” said Kathleen Alexander, the William E. Lavery Professor in the Department of Fish and Wildlife Protection. “By using dirigible systems, we can learn much more about how disease dynamics are affected by host behavior and environmental factors, including urbanizing landscapes.”

A dirigible system can be found with social groups of banded mongoose, also called troops, who live in urban and natural areas in Botswana. For the past 20 years, researchers from the Chobe Research Institute and CARACAL, a non-profit organization co-founded by Alexander, have observed the behavior of mongoose troops in the natural environment of Chobe National Park and in increasingly urban centers such as Kasane.

Botswana’s banded mongooses are ideal study objects because they live in territorial social groups in the landscape and are infected with a novel tuberculosis pathogen in northern Botswana, which is closely related to human tuberculosis.

“We are looking for the dispersal behavior and movements of mongoose that could allow disease transmission between these troops of mongoose,” said Professor Eric Hallermannwho specializes in population genetics and is a co-author of the paper. “This species usually lives in troop structures that are resistant to the immigration of other troops, so knowing how they move and interact through the landscape is important.”

“They are difficult to follow locally because they look so similar, unlike cheetahs, for example, which can be individually identified by their spots,” continued Hallerman, who is a subsidiary of Virginia Tech along with Alexander Fralin Life Sciences Institute. “You can add ear tags and other markings, but they often lose the markings, making it difficult to track people between troops. Genetic approaches are key to solving these difficulties.”

The researchers needed samples for this. “We decided that the best option to assess the genetic diversity of the troops is to collect fresh stool samples,” said Kelton Verble, the paper’s lead author, who graduated from Virginia Tech in 2018 with a Masters in Fisheries and Wildlife Sciences He refined the sample collection processes, tracked mongoose across landscape types, and collected fecal samples from a variety of troops.

“We also looked at the health of the mongooses that were moved between the study groups,” he said. “Our previous data showed that animals infected with tuberculosis tended not to spread, and the data from this study support this original finding.”

Genetic data obtained from microsatellite DNA markers within the genome sequence of each animal made it possible for Verble to identify not only individuals who had moved between troops over the course of their lives, but also the general genetic makeup of the various troops in the Characterizing the landscape – how were the individuals connected to one another? and how would this affect the potential for disease transmission?

“With this study, we really wanted to explicitly examine the spread and clarify what happens between and between troops across land types,” said Alexander, who is also a member of the Fralin Life Sciences Institute’s new Center for Emerging, Zoonotic and Arthropods. Transmitted pathogens. “What we saw was that these urban landscapes changed not only foraging behavior, aggression and the use of caves, but also the spreading behavior and, consequently, the potential for disease transmission.”

The researchers found that mongooses that live in urban landscapes are more likely to spread to other troops in this type of land, increasing the likelihood of tuberculosis transmission. With more abundant human-related food sources, troops closer to the city were also more likely to share caves and overlap their home territories.

“The banded mongoose is usually thought of as a philopatric species, which means that if it is born in a troop, it will stay there for life,” said Verble, who is now a PhD in genomics at the University of Alabama. “What we learned is that far more people were exchanged between troops than was thought, which is vital in predicting the spread of disease.”

Such results not only have implications for the transmission of disease between animals, but also for understanding how zoonotic diseases such as COVID-19 are transmitted from animals to humans and how urbanization might affect this spread.

“We have never been very good at predicting disease occurrence events,” said Alexander. “We don’t know when a pathogen will appear and we can’t predict what will happen because there are so many possible influences. Understanding how animals interact with and are influenced by animals is becoming increasingly important for zoonotic pathogens. ”Transforming landscapes and growing urban centers, information that is critical to further developing our toolkit to address public and animal health challenges. “

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Written by David Fleming

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