Animal videos from ‘bat feast’ in African cave offer clues to how deadly viruses spread

Researchers filmed 10 species of bats eating or scavenging in a known Marburg virus hotspot and surprised hundreds of visiting humans.

By Edward Chen & Nature magazine

When researchers in Uganda set camera traps to monitor African leopards (Panthera pardus pardus) and spotted hyenas (Croquettes kibbles) in a national park last year, they didn’t know they were going to record much more than just these animals. Several of the traps, placed outside a cave known to harbor Egyptian fruit bats (Rousettus aegyptiacus), captured on video a multitude of creatures feasting on winged mammals. Bats are known to carry the Marburg virus, which can transmit to humans and cause fatal hemorrhagic fever. The images therefore offer a real-time insight into how the disease can spread.

Scientists know that bats can transmit viruses to humans either directly or through an intermediary animalSince forensic detective work and other studies. The Ugandan team believes this is the first time potential intermediate animals have been filmed in a hotspot known for Marburg viruswhich belongs to the same family as the Ebola virus. “It’s certainly the first in such a well-documented form,” says Gábor Kemenesi, a field virologist at the University of Pécs in Hungary, who was not involved in the study.

The researchers, who published their results today in the journal Current biology after publishing them in a Zenodo preprint 10 months ago, reported filming 10 species feeding on or catching bats at Python Cave in Uganda’s Queen Elizabeth National Park. They saw blue monkeys (Light Cercopithecus) diving into the cave to catch bats, a fight between a crowned eagle (Stephen was crowned) and a Nile monitor (Varanus niloticus) about two bats caught by the eagle and a leopard standing almost upright to catch the bats from the cave. This could be the first confirmation that leopards hunt bats alive. “This has never been seen,” says study author Alexander Braczkowski, scientific director of the Kyambura Lion Project in Kampala. “Sometimes he would eat 30 to 40 bats a night.”

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Dangerous visits

What’s even more astonishing is that the team filmed more than 200 people – tourists, interns from a local wildlife institute, and children with school groups – approaching the cave during the four months the cameras were active. Only one visitor, a tourist, wore a mask. This is despite warnings posted around the cave about the Marburg virus, for which there is no proven treatment or vaccine.

“I was quite shocked,” says Elke Mühlberger, a virologist at Boston University in Massachusetts. Contact with caves is the main known factor for humans contracting Marburg virus. According to an unpublished analysis shared with Nature According to Adam Hume, a virologist at Boston University, 43% of the 21 Marburg outbreaks confirmed since 1967 have been associated with visits to a cave. For 29% of households, contact with a cave was excluded; the others have unknown origins.

The bats of Python Cave have actually been directly linked to the Marburg outbreaks. A 2007 outbreak at the Kitaka mine, 50 kilometers from the cave, was traced to bats flying into the cave. And two tourists who visited the cave in 2007 and 2008 were infected. One of them died. There are conflicting accounts as to whether the tourists entered the cave or simply looked in; the surviving tourist tells Nature that they went about 10 feet into the cave and “looked inside for at least 30 minutes.” Jonathan Towner, a viral ecologist at the US Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, who visited and extensively sampled the site, says they likely came into contact with bat droppings or urine during their flight.

Warning signs

These incidents led to the construction of a partially enclosed viewing platform 30 meters from the cave entrance in 2011, as well as the installation of warning signs to keep visitors away. “From a tourism standpoint, you obviously don’t want your visitors to be potentially infected,” says Trevor Shoemaker, a CDC epidemiologist who was stationed in Uganda during construction and consulting on the project.

And yet, visitors openly flout the rules and come within “a few meters,” says Braczkowski. This wasn’t obvious before the team set up their camera traps, says Bosco Atukwatse, an ecologist with the Kyambura Lion Project and author of the study. The area appeared “really untouched,” says Atukwatse, who has since informed park management of the team’s findings.

The Uganda Wildlife Authority, which manages Python Cave and surrounding wildlands, did not respond to questions. Naturerequest for comment.

Seeing all the animals on camera and suddenly understanding the connection between Python Cave and the story of the Marburg virus – “it was a pretty shit moment for the whole team,” Braczkowski says. “It’s not just a bat nest.”

This article is reproduced with permission and has been published for the first time April 20, 2026.