The Ebola Cave

It’s been a few years since I’ve read The Hot Zone, but IIRC the cave the author visits at the end of the book is thought to be the birthplace of the ebola virus and other nasties. So I got to thinking, why doesn’t someone go into the cave and sterilize it? I mean, it’s been the point of origin of at least one really nasty disease and could potentially be the starting point of another equally nasty disease. It seems to me that it makes sense to kill everything currently in the cave and make it an environment hostile to all life for some time in hopes that this reduces the chances of something else being unleashed from there. Would this work?

It’s called Kitum cave. It was a suspected source because it was the last identified African site a western (anthropologist?..some kind of naturalist) visited before flying back to London and promptly dropping dead of the disease. It’s not been sterilized because no one ever found and animals or insects in it that were carrying the virus. Test results were negative.

The author of Hot Zone is Richard Preston.

Okay, but if they had discovered ebola in there, would they have sterilized it? And if not, why not?

Kitum Cave on Mount Elgon, on the Kenya-Uganda border, was suspected to be a source not of Ebola but of Marburg, a less lethal but still spectacularly nasty relative of Ebola. (Marburg and the several known strains of Ebola are known as the filoviruses, from the Latin word for “thread”.)

A French expatriate in Kenya, referred to in the book as “Charles Monet”, died of Marburg in 1980 within a few days of visiting Kitum Cave. In 1987, a 10-year-old Danish boy (in the book called “Peter Cardinal”) died of Marburg in Nairobi. When his movements were traced back, it turned out he had also visited Kitum Cave. Since that seemed to be the only place on Earth where those two people’s paths had crossed, and they were both killed by the same virus, it seemed logical to suspect Kitum Cave of being the lair of Marburg, as it were, or one such lair, at any rate. A U.S. Army virologist named Gene Johson and a Kenyan, Peter Tukei, organized a joint U.S.-Kenyan expedition to the cave. The expedition members wore biohazard suits inside the cave, and took biohazard-laboratory-level precautions. They collected numerous samples–insects, ticks, rodents, birds, and bats–and also brought monkeys and guinea pigs in cages which were exposed to the air and evnironment of the cave. They took blood samples from the people in the villages nearby. All of the samples tested negative, and none of the monkeys or guinea pigs got sick.

As to sterilizing the cave if it had tested positive for Marburg, Kitum Cave is home to numerous species of wildlife, many endangered, from bats to elephants and leopards. Not only would that raise ecological and conservation concerns about sterilizing the place, but it would make it rather pointless to boot. Kitum Cave is hardly isolated from the rest of the planet–bats, leopards, elephants, and so on all freely travel back and forth between the cave and the outside world.

I don’t believe the natural reservoirs of any of the filoviruses–Marburg or the Ebolas–has yet been identified. The Ebola strains were first identified in southern Sudan and northern Zaire (now the Democratic Republic of the Congo), hundreds of miles from Mount Elgon. The monkeys who died in suburban Washington, D.C., of what was dubbed “Ebola Reston”–which apparently doesn’t infect humans, although it seems most closely related to the highly-lethal Ebola Zaire–came from the Phillippines, not Africa. There have since been outbreaks of Ebola in western Africa, halfway across the continent from where it was initially seen. Marburg itself is named after a city in Germany where the first documented outbreak took place among laboratory workers who were apparently exposed to African monkeys imported for medical research. So sterilizing caves is probably somewhat beside the point. A virus isn’t some dragon that can be killed with a lance or a sword or a big bomb if you can just track down where it lives. The expedition was simply trying to identify a source and a natural habitat of one of the viruses so we can understand them better and find ways to cope with them.