SCHOOL groups and tourists are visiting a bat-filled cave riddled with Marburg virus, previously flagged as having pandemic potential.
“Python Cave”, in western Uganda, is home to tens of thousands of fruit bats, some of which carry Marburg, that can kill up to half of those it infects.
A close cousin of Ebola virus, Marburg outbreaks have occurred in Africa, most recently in Tanzania in January 2025.
Scientists monitoring the cave, nestled in the Maramagambo Forest in Queen Elizabeth National Park, recorded hundreds of people wearing no protective gear near the site, where a tourist once caught Marburg and died.
The camera traps recorded an estimated 400 humans visiting the cave “including school groups, tourists, and local trainees – the majority with no personal protective equipment”.
Dr Colin Butter, a professor of Bioveterinary Science at the University of Lincoln, told The Sun that this was “very concerning” for “the health of those entering the cave and for possible onward transmission to families and other close contacts”.
The remarkable new footage captured by researchers also shows leopards, monkeys and other predators snatching bats as they swarm out of the cave.
The cave is home to an estimated 56,000 Egyptian fruit bats, around seven per cent of which carry Marburg, meaning several thousand bats inside the cave could be carrying the disease.
The virus has previously been flagged by the World Health Organisation as a “priority pathogen” with pandemic potential.
It warns that the risk can be reduced by “reducing the risk of bat-to-human transmission arising from prolonged exposure to mines or caves inhabited by fruit bat colonies”.
The researchers say there are warning signs and a viewing platform to keep visitors safely away from the cave, but many visitors still went close, without protective gear.
Over five months last year, the experts recorded at least 14 different predator species visiting the cave to hunt or scavenge bats, including baboons, civet cats and birds of prey.
In one clip, a leopard can be seen approaching the entrance to the cave, swiping at bats before leaving with one in its mouth.
Another, shows a troop of monkeys grabbing bats as they fly from the cave.
The cameras were originally installed by Ugandan wildlife biologist Bosco Atukwatse while studying lions and hyenas in Queen Elizabeth National Park.
There is currently no evidence that any of the animals have caught Marburg.
Instead, they captured what scientists say is a rare glimpse of how wildlife species interact around a known disease reservoir – in this case, bats.
Bats are thought to be the main reservoir for the virus in the wild, and can carry Marburg and pass it on without falling sick themselves.
Alexander Braczkowski, scientific director of the Kyambura Lion Project and a co-author of the research, told The Sun that Python Cave creates unusually easy access to the bats.
“Normally bats are protected by spatial buffers,” he said.
“They roost high in the ceiling. But in this cave, that protection disappears.
“The bats are roosting at eye level of animals.
“The bats defecate downwards and create guano (bat droppings) mountains that grow larger and larger, allowing predators (of all sizes) easy access to them.”
In a preprint of their findings, researchers described the cave as a “spillover crucible”, adding that many of the species feeding on the bats are themselves eaten by humans as bushmeat.
They said that the discovery of so many animals feeding on the bats “may represent a Rosetta Stone for interpreting the real-time mechanics of zoonotic spillover”.
This is when viruses jump from one species to another, giving them the chance to evolve, adapt and potentially spread more easily in humans.
In 2008, a Dutch tourist who visited Python Cave caught Marburg and died. And a US tourist also fell ill after visiting the cave but survived.
However, the scientists stress the footage does not show that the virus has already spread between species.
Dr Efstathios Giotis, a molecular virologist at the University of Essex who was not involved in the research, said: “The key point is that this is ecological evidence of contact, not virological evidence of spillover.”
The scientists did say the close contact seen in the footage could expose animals, like primates, to infected blood or body fluids.
This is especially concerning as there is evidence to suggest primates can spread the virus after interacting with bats.
Primates like monkeys are particularly important because they are biologically closer to humans than bats, meaning the virus could jump to humans more easily.
Professor Ed Hutchinson, a virologist at the University of Glasgow who was also not involved in the research, said viruses are normally adapted to grow in one specific species.
“Viruses are fine-tuned to replicate in a specific host species,” he explained.
“A virus that is good at growing in one animal is unlikely to be good at growing in another.
“Monkeys are much more similar to humans than bats are, so if a bat virus infected a monkey, it would have a chance to evolve into a form that could be more likely to infect humans.”
Dr Colin added: “While Marburg will transmit to primates and then transmit between individuals through body fluids, each infection of a primate increases the possibility that the virus will mutate and become better able to do this, increasing human-to-human transmission.”
Previous outbreaks in Africa have seen around half of people infected die, though in places with poorer healthcare that has risen to nearly 90 per cent.
While several vaccines are in development, none have yet been approved.
The virus spreads between people or animals through close contact with the bodily fluids of infected individuals or contaminated surfaces.
Symptoms include high fever, intense headaches, muscle pain, diarrhoea, and vomiting.
In severe cases, death can result from massive blood loss from different parts of the body, including the eyes.
What is Marburg virus?
Marburg is a filovirus like its more famous cousin, Ebola.
These are part of a broader group of viruses that can cause viral haemorrhagic fever, a syndrome of fever and bleeding.
Up to 90 per cent of those infected die.
The first outbreaks occurred in 1967 in lab workers in Germany and Yugoslavia who were working with African green monkeys imported from Uganda.
The virus was identified in a lab in Marburg, Germany.
Since then, outbreaks have occurred in a handful of countries in Africa, less frequently than Ebola.
Marburg’s natural host is a fruit bat, but it can also infect primates, pigs and other animals.
Human outbreaks start after a person has contact with an infected animal.
It’s spread between people mainly through direct contact, especially with bodily fluids, and it causes an illness like Ebola, with fever, headache and malaise, followed by vomiting, diarrhoea, and aches and pains.
The bleeding follows about five days later, and it can be fatal in up to 90 per cent of people infected.
