It is hard to fathom that, after the hours toiled during "kill weekend," the virus hunters' search for possible mainland spread, and the vigorous decontamination efforts of both laboratory buildings and the 840-acre island grounds, a single animal capable of spreading exotic viruses would have been kept alive. But sixty sheep were. And they vaccinated the sheep outdoors with Rift Valley fever vaccine — inactive viruses that could revert to a virulent state and turn the test herd into virus incubators. This violated the cardinal rule established by Plum Island's first director, Doc Shahan: no experiments shall take place outside the containment laboratory. "No virus studies are conducted except in the enclosed laboratory buildings, and no contact is possible with other livestock or with birds and insects." Scientists were taking an immense risk to free up laboratory space. After the outbreak, Dr. Callis asked a panel of national biosafety experts a question: could animals vaccinated against foot-and-mouth disease virus (far less dangerous to humans than Rift Valley fever virus) be held outside, to save space? The experts said that animals could be injected with vaccines outside, but only if they were genetically engineered vaccines of U.S. origin, essentially synthetics that didn't contain actual virus. This reduced to nil the risk of reverting to virulence and transmitting disease. But that wasn't the case with Rift Valley fever virus vaccine, which was authorized to be tested outdoors on Plum Island.
The jagged Great Rift Valley runs along the eastern spine of Africa, the result of a series of faults that first appeared when Africa separated from the Arabian peninsula thirty million years ago. The Rift snakes some four thousand miles, from Zambia in southern Africa up through Mozambique, Tanzania, Kenya, Uganda, and Ethiopia, and under the Red Sea to the Jordan River valley. In Olduvai Gorge, deep within the lower reaches of the Rift Valley, shadowed by towering volcanoes such as Kilimanjaro and Mount Kenya, scientists unearthed the oldest fossils of the human species Homo erectus, dating over 500,000 years. From this cradle of human existence has spawned some of the deadliest natural threats to human life known to mankind.
On a farm near Lake Naivasha, heavy rains in July 1930 were followed by 3,600 lambs and 1,200 ewes falling violently ill and dying within days. Perplexed by the sudden tragedy, local veterinarians and scientists rushed to the scene to examine the remains and take blood and tissue samples for further study. Back at the lab, four staff members came into direct contact with the tainted blood and contracted an acute febrile (fever producing) disease that resembled sandfly fever. It turned out that every farmhand in the area had been suffering a similar ailment. To prove conclusively the mysterious culprit was infectious to humans, the scientists inoculated a man with a sick lamb's blood, then used his serum to successfully pass disease on to healthy sheep. Further tests revealed that the offending agent was a virus. More lab workers contracted the volatile disease, named the Rift Valley fever virus, working on it back in England. One year later, the disease struck again while sixty miles from the original outbreak. Both cases were matched to the same germ. The new germ wasn't particularly deadly, but it did cause severe sickness, and could cause blindness.
During World War II, Plum Island founder Dr. Hagan realized the terrific potential of Rift Valley fever as a germ warfare weapon. He put the new virus at the top of the list of agents the Axis powers might use against the Allies, along with anthrax, yellow fever, and botulism. Hagan deemed it "particularly dangerous, since the virus was hardy" and "difficult to diagnose." In addition to causing near-fatal 107-degree fevers and severe flulike symptoms, it ruptured blood vessels and caused the eyes to hemorrhage profusely. The bleeding blocked the optical nerve and often caused permanent blindness.
In a top-secret wartime report to George Merck, Hagan's colleague Dr. Thomas Rivers noted that the virus would make a fine weapon. "Rift Valley fever in humans does not kill people as a rule, yet a widespread epidemic would be demoralizing." Rivers, a head scientist at Rockefeller (and the boss of Dr. Richard Shope), also suggested use of a biological cocktail— similar to a designer germ weapon the Nazis were designing — using mosquitoes. "[I]t would be interesting to find out whether the same mosquitoes could be simultaneously infected with [Rift Valley fever, yellow fever, and dengue fever] viruses and be capable of producing concurrent epidemics in a susceptible population…. "
After the war, the Army biowarriors put Dr. Rivers's plans into practice. Pentagon scientists briefed President Dwight D. Eisenhower on using Rift Valley fever as a nonlethal biological weapon that would only "incapacitate" the enemy, rather than kill him. Used correctly, it could deter and demoralize the enemy and, at the same time, spare buildings and infrastructure from incendiary bombs. The president approved funding in this new area of weaponry, calling it "a splendid idea." Research on incapacitating germ agents began.
Starting experiments at its new Plum Island laboratory, the USDA asked a South African scientist for instructions for handling Rift Valley fever. He warned, "Never have we handled a virus which spreads so quickly, easily, and rapidly as virulent as Rift Valley fever virus…. It is now a special instruction here that this virus is handled in complete isolation."
NAMRU-3
In October 1977, James Meegan, commander of United States Naval Medical Research Unit No. 3 (NAMRU-3), noticed thousands of Egyptians in scattered parts of the country falling mysteriously ill. Some 200,000 people, young and old, flooded into hospitals with eye infections, fevers, and myalgia. In the towns hardest hit, two-thirds of the populations contracted disease. Many contracted encephalitis (an acute inflammation of the brain) and hemorrhagic fevers (uncontrolled internal bleeding). Hundreds were dying. An epidemic had erupted, coinciding with noticeable large swarms of mosquitoes. Doctors feared it might be the Marburg virus discovered in Germany in the late 1960s, the older brother of the Ebola virus.
NAMRU-3 collected samples in one of the high-infection locations and shipped the materials to Yale University's Arbovirus Research Unit (YARU). Dr. Robert Shope, head of YARU, found that Egyptian samples reacted to antibodies of Rift Valley fever, an arbovirus, a family of viruses that are communicated by bloodsucking insects. The diagnosis was surprising, since previous experience had shown Rift Valley fever to be rarely fatal. Major C. J. Peters — the intrepid virus hunter from Fort Detrick featured in Richard Preston's harrowing chronicle of the Ebola virus, The Hot Zone — called it a "unique situation. We didn't know of any other virus that caused such a wide range of illnesses….They were like totally separate diseases."
Shope was extremely uncomfortable with the thought of a now-lethal virus strain in his Connecticut laboratories. "Rift Valley fever was not supposed to be worked with in the United States — it's a foreign animal disease," he recalls. "As soon as we found out what it was, we wrapped up work, disinfected the place, and sent the materials out to Plum Island." The new Rift Valley fever virus was carefully shipped across the Long Island Sound to Plum Island and deposited in the virus library alongside five other earlier, less deadly strains the Army had procured for the USDA:
OPERATION WHITECOAT