Humans have made palm trees extinct and chimpanzees, monkeys and antelopes now eat bat guano that contains viruses similar to Covid-19
[29 Aprile 2024]
The study “Selective deforestation and exposure of African wildlife to bat-borne viruses”, published on Communications Biology by an international team of researchers led by Pawel Fedurek and Caroline Asiimwe of the Budongo Conservation Field Station – Uganda, has shed new light on virus spillovers between different species that can cause pandemics.
Fedurek, a researcher from the Faculty of Natural Sciences at Britain’s University of Stirling discovered animals in an African forest eating bat droppings – guano – after a key food source in the region disappeared following selective deforestation. Laboratory analysis of bat guano has identified a number of viruses, including a betacoronavirus related to SARS-CoV-2, the virus that caused the Covid-19 pandemic. It is not known whether the betacoronavirus found in guano is transmissible to humans, but it provides an example of how new infections could overcome barriers between species.
The study began when Fedurek observed wild chimpanzees consuming bat guano from the hollow of a tree in Budongo Forest, Uganda. The researcher then set up cameras that recorded chimpanzees, monkeys and antelopes eating the excrement.
Guano has become an alternative source of crucial minerals after palm trees that were once consumed by mammals were cut down, leading to extinction. The palm was used by the human inhabitants of Budongo to dry tobacco leaves which were then sold to multinationals.
At the University of Stirling they recall that «Scientists do not yet fully understand the early stages of the spread of the virus, which can lead to the death of tens of thousands of people, but it is believed that they involve complex causal chains that begin with the alteration of environment by humans.”
Fedurek emphasized that “Our research illustrates how a small form of selective deforestation, ultimately driven by a global demand for tobacco, can expose wildlife and, by extension, humans to viruses. residents in bat guano, increasing the risk of spreading the virus. Studies like ours shed light on the drivers and pathways of virus transmission from both wildlife to wildlife and wildlife to humans, ultimately improving our abilities to prevent epidemics and pandemics in the future. Most research into epidemics and pandemics has focused on reducing the spread of the virus, for example finding an effective vaccine, rather than preventing animal-to-human transmission of the virus. Our work highlights the importance of studying disease ecology before diseases reach humans.”
After discovering mammals that eat guano, Fedurek and Asiimwe (then conservation coordinator of the Budongo Conservation Field Station) involved Tony Goldberg of the University of Wisconsin-Madison, one of the world’s most famous experts in the epidemiology and evolution of infectious diseases , who identified viruses in guano in collaboration with researchers who quantified the mineral content of guano (Jessica Rothman of Hunter College of the City University of New York) and established the likelihood that the new betacoronavirus will infect three species of mammals and human beings (Gregory Rice of the US Naval Medical Research Command). Due to the extent and complexity of the laboratory analyzes required, the entire project took approximately 6 years to complete.
For Goldberg, «Our study links tobacco cultivation to the exposure of at least three species of African wildlife to bat viruses. We believe this is a textbook example of how new infections could cross species barriers even before reaching humans. This is important because the initial stages of the onset of epidemics, epidemics and pandemics have been particularly elusive to science. We may have come across a series of events that are usually hidden from the view of epidemiologists and public health officials. Our study may be particularly relevant to the origins of bat-borne diseases such as coronaviruses and, perhaps, Ebola. It is hoped that the discovery will make it possible to implement interventions that break these types of causal chains, ultimately helping to prevent future pandemics.”
Asiimwe concluded: “Our study demonstrates that human activities that alter the environment can lead to devastating health consequences for both wildlife and humans and we should therefore urgently learn to use natural resources sustainably. Considerable research efforts are also needed to study how forest degradation and other forms of human activities can influence the behavior of wildlife in ways that expose them and humans to dangerous viruses.”
