At the time, of course, the idea that gay men in LA were dying of a disease from wild monkeys in Africa would have been absurd. Preston calls AIDS “the worst environmental disaster of the twentieth century.” He explains that HIV most likely jumped to the human race from African primates, possibly when monkey hunters “touched bloody tissue.” He goes on to recount that HIV was first noticed in 1980 by a Los Angeles physician who observed that his gay male patients were dying of an unknown illness. For a moment he turns off his lamp and stands in darkness, listening to his heart beat in his chest and his blood drum in his head. Further still he finds a giant room, hundreds of yards across. He continues on, finding a crevice full of water. Preston acknowledges how little he understands about the cave and its inhabitants. Deeper still, he finds spiders and insects-perhaps they bit Monet and Cardinal, transmitting Marburg that way. He notes that had he not been wearing protective gear, the rock would have cut his scalp-yet another potential exposure to the virus. He finds a side tunnel and heads down it, abruptly slamming his head against a rock. He sees an elephant dropping, followed by a wall that the elephants have dug into with their tusks. He continues along, disturbing another colony of bats, and finding a fossilized tooth of a crocodile in the rock, a remnant of the volcanic eruption of Mount Elgon. He speculates that perhaps Peter Cardinal cut himself on one. There are crystals too, which look very sharp. Preston reaches the top of a mound in Kitum Cave and puts his hand on the ceiling, which is made up of solidified ash and petrified trees. Preston states that viruses “like dry air and dust and darkness,” meaning that this kind of cave is the perfect place for one to hide.

Beyond the bat colonies the cave is dry and dusty-strange for a cave, since caves are usually wet. Meanwhile Preston treks further and further into the cave, disturbing bats with his light and noting their wet droppings on the walls. Preston explains Iain Redmond’s theory that thousands of generations of elephants actually carved the cave as they pried out rocks in search of salt. He wore no biohazard gear but never fell ill (and later Peter Jahrling would express an interest in testing his blood). He carries with him a map on a waterproof bag (so that he can decontaminate it) drawn by an Englishman named Iain Redmond who once lived in the cave for three months to study elephants. He observes that in 1982, the roof of the cave fell in, meaning that the entrance to the cave is covered in fallen rock. Preston enters the huge mouth of Kitum Cave and walks across a floor covered in bat dung.

The Hot Zone by Richard Preston