The Hot Zone opens with the story of Charles Monet, a Frenchman who lives in Western Kenya. In January 1980 he decides to explore Kitum Cave, a natural landmark located on a peak called Mount Elgon. A week later he becomes ill with a fever and vomiting, and he grows so ill that he must be flown to Nairobi Hospital. On the plane he continues vomiting, and when he reaches the hospital, he begins to hemorrhage, getting blood and vomit all over a physician named Dr. Shem Musoke. Monet dies a short time later, and soon afterward, Dr. Musoke also becomes ill. All of his internal organs begin to fail, and his blood refuses to clot. His physician, Dr. David Silverstein, sends a sample of his blood to a lab in South Africa and the Centers for Disease Control in Atlanta, Georgia. They send him back a diagnosis: Marburg virus, which first broke out in Germany in 1967 after factory workers were exposed to infected monkeys.
Marburg, Richard Preston, the author, tells us, kills one in four of its victims—an immense percentage. It is part of a family called filoviruses, which also includes two deadly diseases called Ebola Sudan (which kills 50% of its victims) and Ebola Zaire (which claims 90%). These viruses attack every organ in the body, causing both massive bleeding and deadly blood clots. Like AIDS, Marburg is passed to humans by monkeys. Also like AIDS, it generally only passes through “direct contact with blood and bodily fluids.”
Dr. Shem Musoke, miraculously enough, begins to get better, and no one else falls ill. His blood is sent out to laboratories all over the world so that they can study the virus. One of the institutions to receive it is the US Army Medical Research Institute of Infectious Diseases (USAMRIID), also called the Institute.
Preston takes us to 1983 and introduces us to Nancy Jaax (a Major at the time) and her husband Jerry Jaax, both of whom are veterinarians in the US Army. Nancy works in a Level 4 laboratory at USAMRIID, meaning she handles diseases that have no vaccine or cure with the protection of a spacesuit.
Heading research on Ebola at the Institute is Eugene Johnson (Gene), who has hunted Ebola for decades—most scientists are too scared of the virus to work with it. He injects monkeys with Ebola Zaire (using a strain taken from a now-dead nurse named Mayinga) and then attempts to cure them. It is Nancy’s job, along with her superior, Colonel Anthony Johnson (Tony), to dissect the monkeys when the cures fail (as they always do). After the laborious process of putting on a spacesuit, Nancy and Tony enter the hot zone and begin their dissection. They continue until Tony notices a tear on Nancy’s outer glove (they both wear three layers). She exits the dissection room immediately and is horrified to see that the blood has gotten to her innermost glove—but it has not touched her hand. She has just barely escaped exposure. The experiment ends soon after this incident—but not before Gene and Nancy discover that Ebola is able to mutate and make itself airborne.
Preston describes the spread of Ebola Sudan in 1976, which was made worse by the use of unclean needles to inject patients, and Ebola Zaire, which kill is what killed Mayinga. He recounts how a team of American doctors identified the Ebola virus and traveled to Africa to try to treat and study it.
Back in 1987, Gene Johnson receives samples of blood from a deceased Danish 10-year-old named Peter Cardinal. He finds that the blood has Marburg within it, and is surprised to learn that Peter, like Charles Monet, had explored Kitum Cave. Clearly, somewhere within the cave, the virus lurks. Gene Johnson attempts a massive experiment to find its source in the cave, but is unsuccessful.
Meanwhile, Nancy and Jerry are both promoted, becoming lieutenant colonels. Nancy becomes chief of pathology at USAMRIID, while Jerry becomes the head of its veterinary division.
We move to Reston, VA, a suburb of Washington, DC, in 1989. In Reston there is a facility called the Reston Primate Quarantine Unit, which stores monkeys that will soon be shipped to labs across the US. It is overseen by veterinarian Dan Dalgard, who begins to notice in October that an unusual amount of monkeys seem to be dying. By November the mysterious disease is still spreading, and Dalgard decides to consult the Institute. He sends samples to a scientist named Peter Jahrling, who in turn sends them to an employee named Thomas Geisbert for analysis under a powerful electron microscope. The two are surprised to find that the cells within the samples are essentially destroyed. Checking for contamination, they take a whiff of the culture, but smell nothing. They come to believe that the virus is probably simian hemorrhagic fever, which is lethal to monkeys but harmless to humans.
When the cells are at last ready to be viewed under the electron microscope, however, Geisbert makes a startling discovery: whatever is infecting the monkeys is a filovirus, and both he and Jahrling may have been exposed. They immediately find Gene Johnson, and go with him to inform Colonel Clarence James Peters (C. J.)—although they keep their potential exposure a secret. They inform Dalgard that something may be amiss, and continue to study the virus. Eventually Jahrling makes another disturbing finding: the virus is either Ebola Zaire—the deadliest form of filovirus—or a very close relative.
The news moves up the chain of command, and the men inform Nancy Jaax, as well as Colonel David Huxsoll, the commander of USAMRIID. He in turn contacts Major General Philip K. Russell, who oversees the Institute. The group decides that they need to inform Dalgard, the local authorities, the Pentagon, and the C.D.C.
Dan Dalgard, meanwhile, remains calm, until he hears that an employee of his, Jarvis Purdy, has had a heart attack—and he fears that it may have been caused by Ebola. A USAMRIID team picks up samples and corpses from the monkey house, and then returns to the Institute. Nancy begins to dissect the bodies, while C. J., General Russell, Gene Johnson, and Dan Dalgard participate in a giant meeting to discuss what to do. After some tension with the C.D.C.—especially the talented but hot-tempered Dr. Joseph B. McCormick, one of the few men on Earth who has actually treated human cases of Ebola—the group decides that the Army will be in charge of euthanizing the infected monkeys.
C. J. contacts Jerry Jaax, who will be involved in the operation as well. Jerry begins to plan with Gene Johnson, seeking to euthanize the animals humanely while ensuring that both civilians and his team remain safe.
After a day of preparation, the operation begins in utmost secrecy, so as not to alert the press and cause mass panic among the public. Soldiers put on spacesuits and begin to euthanize infected monkeys—a dangerous process, considering the monkeys’ sharp teeth and the potential for infection. Nancy dissects some of the dead animals, whose bodies have been essentially destroyed by the virus. Meanwhile another employee of the monkey house, Milton Frantig, begins vomiting—he is immediately rushed into an ambulance. Dan Dalgard decides that he must give the Army permission to euthanize all of the monkeys in the house, since any of them might be infected.
Jerry organizes a team of young soldiers to enter the building, euthanize the monkeys, and collect samples. The operation is draining, dangerous, and horrific as the soldiers trap, inject, and dissect hundreds of monkeys. Still it goes relatively smoothly, with a few close calls as news vans attempt to drive by and investigate. On the second day, however, a monkey escapes—but the next day Jerry is finally able to catch it. Peter Jahrling, meanwhile, runs tests on Milton Frantig’s blood, as well as Tom Geisbert’s and his own, and none of the men appear to have Ebola.
The operation ends, and a team begins to decontaminate the building, killing every life form inside of it. The entire episode has created a mystery: if this disease is indeed Ebola Zaire, why have no humans gotten sick?
Months go by, more monkeys are imported, and yet another wave of Ebola sweeps through the monkey house, exposing another employee to the virus. This time, the Army decides to let the monkeys die out, since the virus seems to pose little danger to humans. Soon after, however, it is found that Jarvis Purdy, Milton Frantig, and two other Reston employees have the virus in their blood, and yet they remain symptomless. This means that the virus can travel through the air, but does not cause harm within humans. A fourth strain of the virus has emerged: Ebola Reston. It is almost identical to Ebola Zaire, except that it can move through the air, and it does not affect humans. A tiny change in its genetic code, however, could make this virus truly deadly.
In August 1993, Preston decides to travel to Kitum Cave himself. He drives along the Kinshasa Highway with a guide and some friends, and describes how the building of the highway made possible the spread of HIV. In other words, AIDS is a symptom of globalization. The team reaches Kitum Cave, and the Preston puts on a rudimentary spacesuit in order to protect himself from the virus that may live inside. He explores the cave and is awed by the wonder and the mystery of the place, yet at every turn, he sees the potential for infection. He emerges and immediately decontaminates and disposes of everything he wore, yet is still terrified that he may have been infected with Marburg.
Preston contemplates the link between the emergence of tropical viruses like Ebola and HIV and the human destruction of the tropical biosphere. He wonders if maybe these viruses are nature’s immune response to the parasitic “infection” of the human race, and speculates that a virus more deadly than HIV may one day emerge to wipe humans from the face of the planet.
Preston takes one last trip, this time to the abandoned monkey house in Reston. Inside he sees plants and insects, as the life cycle reemerges in a place that once harbored a deadly virus. Ebola, he thinks, has disappeared for the time being. But, he warns, “It will be back.”