Soon Marr and his colleague, Curtis D. Malloy, currently an epidemiologist with the Exponent Health Group in Washington, D.C., were scouring the existing literature on the possible scientific causes of the ten plagues of Egypt. The two men reached a theory of the plagues as an escalating series of interconnected events, starting with an algae-laden "red tide" (rivers of blood) and culminating in the tenth and most devastating plague (the death of the eldest), attributed by Marr and Malloy to mycotoxins. Their findings were published in the Spring 1996 issue of Caduceus: A Humanities Journal for Medicine and the Health Sciences.

Marr's life since then has mirrored his and Malloy's theory in a way: the Caduceus article led to a Web site and a documentary film (featuring Andrew Spielman of the Department of Immunology and Infectious Diseases), which aired on the Learning Channel in April and on Great Britain's Channel 4 in August. The article also formed thebasis of The Eleventh Plague, the contemporary thriller Marr co-wrote with novelist and friend-of-a-friend John Baldwin. Published by Harper-Collins earlier this year, the novel is due out in paperback next January. Film rights were sold to 20th Century Fox and the second novel of the authors' two-book deal is in the works.

The Eleventh Plague is not Marr's first novel; neither is the attention generated by his article his first 15 minutes of fame. He wrote a novel titled The Black Death (1977) with Gwyneth Cravens, three children's books, and an unpublished novel on Typhoid Mary. As director of the Bureau of Preventable Diseases and principal epidemiologist for the New York City Department of Health from 1974 to 1980, Marr was often in the media spotlight. After that experience, "Everything else is like a Frank Sinatra song," he says. He describes a 1978 outbreak of Legionnaires' Disease in New York City as "the most stressful time, but also the most enjoyable time, working on a real epidemic," that he has ever had. Marr is currently medical director of MD Health Plan/Physician Health Services, a managed care company in Shelton, Connecticut.

In The Eleventh Plague, Marr and Malloy's theory about the plagues of Egypt becomes the tool of a mad scientist. Part Norman Bates and part Unabomber, Theodore Kameron targets members of the religious right whose organizations have refused him research grant money; his revenge takes the form of acts of bioterrorism that recreate the ten plagues. While describing his villain, Marr slips on the name Kameron at one point, saying "Kaczynski" instead. But he insists that the similarity is a coincidence. Marr and Baldwin named their villain Teddy Kameron after the Greek term tetragrammaton, referring to the four Hebrew letters that form Yahweh. That was in December 1995. It wasn't until April 1996 that Theodore Kaczynski was arrested and accused of being the Unabomber, becoming an overnight household name.

Not all the novel's resemblances to fact are coincidental. Marr says he hasn't heard any complaints about the science or the history woven into The Eleventh Plague. And the novel's two heroes are based on reality: The first is maverick virologist Jack Bryne, modeled after Dr. Jack Woodall, director of the New York State Department of Health's Arbovirology Laboratories. The two Jacks (fictional and nonfictional) are both affiliated with PROMED (Program for Monitoring Emerging Diseases), the novel's second hero and a real life project of the Federation of American Scientists.

PROMED was formed as an Internet-based collaboration of experts, working to pinpoint and make the best use of the world's scientific and medical resources for surveillance of emerging diseases around the globe. Anyone interested in emerging diseases and willing to receive an onslaught of electronic mail can subscribe to PROMED-mail, which is PROMED's e-mail list (subscribers may also contribute reports of disease occurrence). In the novel, Bryne moderates Promed-mail, using it to solve the mystery of the ten plagues. Marr says his motivation for writing The Eleventh Plague was not personal fame and glory, but to raise money for Promed. He and Baldwin have designated two and a half percent of their profits to Promed.

Aside from helping to support Promed, Marr hopes his novel will educate people about the threat of bioterrorism. Marr wonders, "What if Teddy Kaczynski had majored in biology instead of mathematics?" and he says that the public needs to be prepared for the inevitable occurrence of biological terrorism.

Is it easy for an epidemiologist to turn novelist? Marr still finds writing novels more difficult than writing scholarly papers. Asked if writing the sequel to The Eleventh Plague has been fun, he quickly answers "no" without expression. Yet as Marr talks about an article he recently submitted for publication, he flashes a mischievous, pleased grin. When his new epidemiologic theory around a historical outbreak of disease is published, it will, he hopes, cause "a firestorm."

- Eman Quotah