In Uganda's Budongo Forest, an unusual and concerning behavior has been observed among wildlife: chimpanzees, monkeys, and antelopes have started consuming bat excrement, known as guano. This behavior has raised alarms among scientists, who have found that the guano is not only rich in minerals but also teeming with viruses, including a relative of the notorious SARS-CoV-2 virus that caused the COVID-19 pandemic. The implications of this discovery could be far-reaching, potentially leading to new human epidemics.
The shift in dietary habits among these animals is attributed to the loss of their primary source of dietary minerals. Local farmers have uprooted native Raphia farinifera palm trees, which the animals used to consume for their mineral content, to make strings for drying tobacco leaves. This deforestation, driven by the tobacco industry, has forced the animals to seek alternative sources of minerals, leading them to consume bat guano. British American Tobacco and other firms involved in the tobacco trade are indirectly linked to this environmental disruption.
The guano, while providing the necessary minerals, also contains a plethora of infectious viruses. According to a study published in Communications Biology, the guano collected from Old World Roundleaf bats tested positive for 27 different viruses, with an average of 14.5 viruses per sample. Although most of these viruses are not harmful to humans, the presence of a SARS-CoV-2 relative is particularly concerning. This finding underscores the potential for zoonotic diseases, diseases transmitted from animals to humans, to emerge from such interactions.
Conservation ecologist Arend de Haas, co-founder of the African Conservation Foundation, emphasized the role of human activities in driving virus emergence among wildlife and humans. He pointed out that activities like deforestation and resource extraction increase contact between humans, domestic animals, and wildlife, creating opportunities for viruses to jump species barriers. This phenomenon is not new; similar mechanisms have been suggested for the transmission of the Ebola virus from bats to humans via infected wildlife.
Tony Goldberg, a professor of epidemiology at the University of Wisconsin-Madison and a lead scientist in the study, explained that the physiological need for minerals, particularly sodium, drives this behavior in wildlife. He noted that chimpanzees crave sodium more than any other mineral, likening their attraction to R. farinifera trees to humans' love for potato chips. With the trees gone, the chimps have turned to guano, despite its risks.
The study's findings are based on observations made between July 2017 and April 2019, during which trail cameras recorded 839 instances of eastern chimpanzees, black-and-white colobuses, and red duikers feeding on guano. This behavior had never been documented among forest-dwelling mammals before and represents a significant shift in their feeding habits. The presence of infectious viruses in the guano adds a dangerous twist to this new dietary pattern.
David Eryenyu, field director at Budongo Conservation Field Station, confirmed that local farmers were unaware of the wildlife implications of cutting down R. farinifera trees. He emphasized the need for alternative livelihood options for communities living around Budongo to prevent further environmental degradation. BCFS is working to diversify local economies and provide education to reduce dependency on forest resources.
The study calls for immediate action to address the root causes of this behavior. Goldberg suggested simple interventions, such as providing farmers with alternatives to cutting down trees, could mitigate the risk. He mused that something as straightforward as supplying a ball of twine to farmers might have prevented the need for deforestation. The broader lesson is clear: understanding and addressing the upstream social forces driving environmental changes is crucial to preventing zoonotic disease outbreaks.
The discovery of virus-laden guano being consumed by wildlife in Uganda's Budongo Forest serves as a stark reminder of the interconnectedness of human activities, environmental health, and disease emergence. It highlights the urgent need for sustainable practices and better management of natural resources to protect both wildlife and human populations from future epidemics.
