November 28, 1989

November 28, 1989, marks the decisive diagnostic turn in the investigation of the Reston monkeys: images of virus multiplying in a monkey’s liver and repeated tests against human blood serum shifted the inquiry from a possible Marburg-like infection to an agent related to Ebola Zaire. The day’s sequence—from Tom Geisbert’s early-morning microscopy to Peter Jahrling’s confirmation and the briefing of senior officers—shows evidence changing both scientific judgment and the scale of the response.

Date and Narrative Position

The date appears as a Tuesday chapter marker in the account of the Reston outbreak. The preceding investigation had raised concern that the monkeys might carry a second agent alongside simian hemorrhagic fever. On November 28, that possibility became the focus of the day’s work. The narrative follows the evidence as it is produced, checked, and carried out of the laboratory: first an image, then a test, then a command decision.

The date is also part of a wider chronology rather than an isolated episode. The book sets the Reston discovery against earlier outbreaks and unresolved questions about how viruses move between animals and people. Those broader histories do not occur on November 28, but they give the day its stakes: the investigators are trying to identify an unfamiliar agent in imported monkeys, while confronting the possibility that a dangerous African virus or a related one has appeared near Washington.

Geisbert’s Photographs

Tom Geisbert began work before dawn. After driving across the Potomac River and through Antietam National Battlefield, he reached Fort Detrick and used his diamond knife to prepare pieces of liver from Monkey O53 for the electron microscope. The resulting photographs showed virus particles budding directly from liver cells. He also found inclusion bodies within the cells. Together, these observations showed that the agent was multiplying in the monkey and that the result could not be dismissed as a laboratory contaminant.

Geisbert took the photographs to Peter Jahrling, and the two brought them to C. J. Peters. The images persuaded Peters that an agent was growing in the monkeys. They did not, by themselves, settle its identity: the team still awaited the results of Jahrling’s tests. The distinction mattered. Visible viral activity established that the monkeys were infected, while identifying the agent required a further comparison with known viruses.

The Test and Its Repetition

Jahrling spent much of the day in his hot laboratory, working with cultured samples and human blood serum. In a dark storage closet, wearing a space suit and using a microscope, he looked for a fluorescent reaction. Serum from Shem Musoke did not glow; serum from Boniface glowed weakly; serum from Mayinga glowed brightly. The last result indicated that the agent in the monkey samples reacted with blood from a person who had died of Ebola Zaire.

Jahrling initially suspected that he had mixed up the samples. He returned to the laboratory, carefully tracked the vials and slides, and repeated the test. The Mayinga serum glowed again. Repetition strengthened the finding, but its meaning remained carefully bounded: the result indicated a close relationship to Ebola Zaire, not definitive proof that the Reston agent was identical to it. The book preserves both the alarm of recognizing the connection and the scientific qualification attached to the test.

From Laboratory to Command

At about 1500 hours, Jahrling was still working through the tests. Once the repeated result convinced him that the finding was real, he contacted Peters from inside the hot laboratory. Peters came to inspect the results, which Jahrling passed through a chemical disinfection tank into the corridor. The procedure made the transfer itself part of the evidence chain: information could move beyond containment only after the paper had been treated.

The two men then took the finding to David Huxsoll, commander of the United States Army Medical Research Institute of Infectious Diseases, who contacted Major General Philip K. Russell. Nancy Jaax was called in because her pathology work could help identify Ebola’s signs in monkeys. At Russell’s office, Geisbert’s photographs and Jahrling’s test results were considered together. The discussion also turned to airborne transmission, drawing on Jaax’s earlier observations and experiments. Thus the day’s evidence did more than name a possible agent: it brought the question of how it might spread into the command-level assessment of risk.

Wider Ecological Frame

The date’s laboratory sequence sits within a book that repeatedly connects outbreaks to animal hosts, human contact, and changing environments, while leaving important links unresolved. Its account of Mount Elgon describes forest being cleared for firewood and grazing as settlement presses toward wildlife habitat. Its discussion of the Lake Victoria region and the primate trade considers how capturing, transporting, and crowding wild monkeys could expose animals and people to viruses. These passages establish possible contexts for spillover, not a proven origin for the Reston agent.

The book’s larger argument about emerging viruses likewise treats ecological disruption as a consequential setting rather than a complete explanation for any one infection. It presents rapid mutation and the movement of viruses through changing ecosystems as reasons their future course is uncertain. Against that expansive frame, November 28 is a sharply bounded day of scientific work: a photograph, a fluorescent reaction repeated under controlled conditions, and results carried through successive levels of authority. Its significance lies in the moment an ambiguous monkey outbreak became a credible, carefully qualified Ebola-related emergency.