ContagionA disease you've probably never heard of destroyed cattle, starved millions, and brought down empires before Tufts veterinarians wiped it off the face of the earth
In Ethiopia, 1889 was known as the year of cattle annihilation. On the heels of an Italian invasion, cattle throughout the country were gripped by a strange new disease. Cows became feverish and lost their appetites, retreating to a shaded spot to sit shivering. Bloody discharge ran from their eyes and mouths, and they suffered gruesome intestinal symptoms that gave the disease its nickname: the green death. Finally, they would collapse from dehydration, dead just days after their first symptoms.
The disease was nearly 100 percent fatal and incredibly contagious. As it spread south, Kenyan tribes watched as it wiped out not only domestic cattle, but also the wild herds of the Serengeti. One Maasai elder later remembered that animals died “so many and so close together that the vultures had forgotten how to fly.” Throughout the continent, nine out of ten cows died. It wasn’t just cattle that suffered. Deprived of their food source, a third of Ethiopians and nearly two-thirds of the Maasai—millions of people, in other words—died of starvation.
Devastating as that epidemic was, it was the just the latest scourge brought about by cattle plague, or rinderpest, as the disease had been named by German biologists. It had ravaged the world since Biblical times—identified as one of the twelve plagues of Egypt in 3000 BC, as a factor in the fall of the Roman Empire, and at least as important as Marie Antoinette’s “cake” in precipitating the French Revolution.
And now it is gone. In May, officials with the United Nations World Organization for Animal Health stood on a stage in Paris and announced the once unimaginable. “Today we witness a historic event, as rinderpest is the first animal disease ever to be eradicated by man,” said the organization’s director, Bernard Vallat. In fact, it is only the second disease ever to be eliminated from the world after smallpox, and in many ways just as significant a feat. “There is no question it represents a huge achievement,” says Marguerite Pappaioanou, executive director of the Association of American Veterinary Medical Colleges. “Rinderpest led to a lot of starvation and famine, which made it devastating to the world population. Now that it’s been eradicated you don’t have to worry about livestock bans, which results in huge savings as well.” Commenting on the eradication at the time of the UN’s announcement, William R. White, an expert on rinderpest at the U.S. Department of Agriculture, went further still: “This is probably the greatest achievement in veterinary medicine,” he said.
If that is true, then it is also not an understatement to say that without the contributions of several researchers from Tufts’ Cummings School of Veterinary Medicine and Feinstein International Center, the eradication of rinderpest never would have happened. In order to defeat the disease, researchers had to accomplish two daunting tasks: developing a vaccine that could withstand Africa’s blistering temperatures, and then finding a way to get it out into the remote grasslands where pastoralists kept their herds. Tufts veterinarians held the keys to both breakthroughs.
The story of the fight against rinderpest properly begins in eighteenth-century Europe. After centuries of devastation wrought on the herds of Europe and Asia, Pope Clement IX’s personal physician, Giovanni Maria Lancisi, declared that any animal found infected with cattle plague must be immediately slaughtered and buried. Punishment for refusal was death by hanging. The measures were severe but effective, and the world’s first veterinary college was founded in Lyons in 1762 specifically to propagate them. Still, animal scientists continued to look for less brutal ways to combat the disease. Over the next two hundred years, biologists worked on vaccines made from live viruses cultured in cattle, goat, and rabbit cells, with varying results. Many caused side effects and left animals susceptible to other diseases; others killed a significant percentage of animals they were intended to save.
That is how things stood when a veterinary student named Walter Plowright was stationed in Kenya during World War II. After witnessing a rinderpest epidemic firsthand, Plowright stayed in Kenya, vowing to produce an effective universal vaccine. Experimenting with new techniques for culturing cells on a single layer of glass, he achieved more uniform results than ever before, finally producing a vaccine that was nearly 100 percent effective and could be used on cows of any age or breed, anywhere in the world.
There was only one problem with Plowright’s vaccine: it had to be kept cold. That wasn’t difficult in Europe or most of Asia, where veterinarians were able to implement massive vaccination campaigns. For those working to eradicate in Africa, however, maintaining refrigeration was a deal breaker. “They used to have an ice-making machine, and they would take these four-wheel drive vehicles with ice chests filled with ice,” says Al Sollod, a veterinarian who was working in Niger before he joined Tufts’ veterinary school in 1981. “Every couple of days they would have to come back and get more ice to bring back into the field. It really limited how far they could go.”
Sollod had worked to combat rinderpest in Niger under a contract with USAID, which he brought with him to Tufts. When the government of Niger kept asking for money to implement the vaccine, Sollod eventually balked, telling USAID their money would be better spent coming up with a way to drive down costs. “If we had to fund them every year, they were just going to fail as soon as we stopped,” he says. “I thought the way to cut costs was to reduce dependency on the cold chain.”
That meant developing something that had never been seriously considered: a vaccine that could withstand African temperatures. To see if it was possible, Sollod turned to Jeffrey Mariner, V87, a veterinary student at the time who had begged him for a chance to get out into the field. Instead, Sollod sent Mariner to the USDA research center on Plum Island, New York, the only facility in the country authorized to work on rinderpest. “I said, ‘This is the closest I can get you to the field,’” Sollod laughs.
Mariner worked in the lab under Jim House, a longtime specialist in vaccine production, who thought he had an idea that might work. Ever since Plowright’s time, the rinderpest vaccine had been freeze-dried to allow it to survive longer—a process almost exactly like freeze-drying coffee to lock in flavor. House thought that if they could find the right additives during the drying process, they might strengthen the structure enough to withstand higher temperatures as well.
The actual experimentation fell to Mariner, who spent hours mixing different chemicals into the vaccine. Starting with seven different compounds, Mariner narrowed them down to three, and eventually just one: a combination of lactalbumin—a protein found in milk—and sucrose, or table sugar. After adding those components, Mariner and House experimented with different drying techniques, finally hitting pay dirt when drying at a low temperature for a longer time, allowing a sugar scaffold to form over the culture. “I always envisioned it as creating a layer of caramelized or crystallized sugar over the virus,” says House. With its new stability, the vaccine would last three months or longer, even at 100 degrees Fahrenheit.
In 1990, Mariner finally got his chance to get into the field as he traveled back and forth to Niger to test the vaccine in real conditions. Using vaccine that had sat unrefrigerated for months, he inoculated 144 calves. Afterward, 141 tested positive for immunity to rinderpest. In just a year and a half, the team had succeeded in producing something remarkably simple yet game-changing: a heat-stable rinderpest vaccine. “Really what we did was apply existing technologies to rinderpest,” says Mariner. “That turned out to be the winning strategy.”
Niger and other countries in West Africa began using the vaccine right away, eradicating the disease within just a few years. In East Africa, however, Mariner and the other veterinary workers would find that rinderpest was not so easily mastered. Even the best vaccine in the world was worthless, after all, if you couldn’t get it to the animals that needed it.
The grasslands of eastern Africa are vast and roadless, thinly populated by itinerant herders who migrate hundreds of miles between the dry and rainy seasons in search of the best grazing land. Down the center of the region, the Great Rift Valley cuts like a scar for 4,000 miles, fringed by rocky hills and volcanic mountains. It’s not a landscape easy to traverse in the best of circumstances. Making it nearly impossible for veterinarians was the political instability that has plagued the Horn of Africa for decades. Tribes with fierce histories of cattle raiding and warfare learned to give each other wide berth in the plains of Ethiopia and Kenya, while civil wars in Sudan and Somalia made for a landscape beset by warring militia groups.
This is the landscape that Berhanu Admassu faced in 1992. Then Ethiopian branch coordinator of the Pan-African Rinderpest Campaign—he’s now a senior researcher with Tufts’ Feinstein International Center—Admassu had worked for five years organizing vaccination drives. Despite his best efforts, the disease hung on in the Afar, a vast region of low-lying plains that forms the northern end of the Great Rift Valley. Admassu and his teams would drive as far into the valley as roads would take them, and set up vaccination stations. There they would wait for herders to bring in their cows. Talking with a community elder one day, however, Admassu learned that what he long feared was true: most of the herders never brought their animals to the vaccination station, deterred by long distances or hostile territory. “The people were bringing in some heifers just to satisfy us, because we were dedicated to vaccinate,” says Admassu, speaking in a slow, measured voice from Ethiopia, where he still works, “but because of the distance and inaccessibility, quite a number of animals were not being vaccinated.”
It was about that time that Admassu heard about Jeffrey Mariner and the heat-stable vaccine, which he hoped might allow them to bring vaccine further into the grasslands. When he got in touch with Mariner in 1992, he found that he was not alone in his problem. In fact, still under the USAID grant, Mariner was hoping to test the new vaccine in areas beyond the veterinary workers’ reach. He and his team had already been experimenting with a new secret weapon: engaging tribespeople to vaccinate their own herds.
The idea had been percolating for some time. Sollod had proposed something similar in his work in Niger, calling for veterinarians to integrate local knowledge into their fieldwork. An affable British veterinarian named Tim Leyland had successfully enlisted local people to help identify and treat diseases in Afghanistan. By the early 1990s, he had been hired by Tufts’ veterinary school, working with UNICEF to implement similar techniques in Southern Sudan along with Andy Catley, another Brit, who was working with a development organization and was hired by Tufts a few years later. But probably the person most responsible for the techniques that made the program successful was Darlington Akabwai, a tall Ugandan field vet who had been working on rinderpest for twenty years, and whom Mariner and Leyland hired to lead their training efforts on the ground.
Back in the late 1970s, Akabwai had been working on a government vaccination campaign in Karamoja, a lawless area of nomadic warrior tribes on the border with Kenya. Like Admassu, he found that jeeps could bring vaccine within reach of just a fraction of the livestock that needed it. Working with the Turkana tribe, he found the sticking point was tribal “seers” whose prophecies would guide the pastoralists to the best grazing land or the areas safest from attack. “We would say, ‘Tomorrow we will bring the jeep and we will meet at such and such a tree,’ ” Akabwai recalls. “But the seers would say, ‘Go on ahead.’ ”
With his big smile and easy, patient demeanor, Akabwai began cultivating the seers, explaining how his vaccines could help them fight the diseases that ravaged their herds. At length, he convinced one of the seers to vaccinate his own animals. “That was the day that everyone brought their animals,” he says. “That was absolutely the best day for me.” Over the years, Akabwai developed a formal training program, in which he’d get communities to appoint their own members to perform vaccinations against a host of diseases. After Mariner and Leyland met Akabwai at a conference on rinderpest, the Tufts team hired him to train community workers to introduce the heat-stable vaccine into remote areas of Sudan, Ethiopia, and other parts of East Africa.
Akabwai would gather herders together to talk about the diseases they were dealing with. Inevitably rinderpest topped the list. “The pastoralists have this traditional knowledge system,” he says. “Their livelihood is based on livestock, they grow up sleeping next to these cows, and they know the diseases better than any veterinary textbook.” But though they recognized the diseases, they knew little about how they were spread or how effective vaccines were at stopping them. To make his case, Akabwai would use local terminology whenever possible. In the Afar, for example, he learned that the native word for rinderpest meant “empty ground”—which is what the land looked like after an epidemic had swept through. “I would tell them, ‘If you want to fill the ground with cattle again, this is the solution,’ ” he says. “Using their own terminology you can easily get them to accept the message.”
He would drive the point home using pictures and stories to show how vaccines worked. To explain why cattle had to be vaccinated three times for the best effect, for example, he and his fellow trainers would draw a picture of a cow and after each vaccination draw a picture of a soldier with an AK-47 standing inside the cow to protect it—an image the herders in the conflict-prone region were sure to recognize. “They understood—they are warriors,” says Akabwai. “Fighting against this disease, they all wanted their warriors to add up to three.” Once he had convinced the elders, he would ask them to identify the most responsible young men to perform the work, showing them how to mix and administer the vaccines. These animal health workers would then make the trek back to their own communities with the vaccines, often traveling miles on foot through the roadless grasslands.
The strongest pushback against the training program came not from the herders but from the veterinary establishment. “They said, ‘Oh no no no,’” Admassu recalls. “‘These workers are illiterate, they can’t do this job.’” In part, Mariner suspects, their resistance was due less to their concerns about the herders’ aptitude than to fear for their own livelihoods. To allay any such fears, the foreigners structured the program to put local veterinarians in a supervisory role, selling vaccines to the young health workers, who would then get reimbursed by the dose from their fellow herders.
The clincher occurred when the head of the Pan-African Rinderpest Campaign, Walter Massega, came to observe the new animal health workers in the field. Ordinarily, performing vaccinations was a wild business. Unlike domesticated cattle, African cattle are tied to a stake at night but otherwise allowed to roam free. To perform vaccinations, vet workers had to frantically herd the animals into a cattle crush and stick them with syringes. The local workers, however, were dealing with their own animals, which were used to the tribespeople’s sight and smells and would allow them to walk calmly up and vaccinate the cattle as they stood in the pasture. Massega was converted. “He came back saying it was a religious experience,” says Mariner. “Years of data didn’t matter—what mattered was seeing it.”
The data itself, however, was hard to dismiss. In the early 1990s, forty-two newly trained animal health workers were sent into the Afar under the supervision of Berhanu Admassu’s government program. Sure enough, the vaccine reached far more cattle than had been possible before. Eighty-four percent of cattle in the area tested immune from rinderpest, up from seventy-two percent with the traditional approach. After a second round of vaccinations in 1994, nobody in the country could find a single case of rinderpest.
The success in the Afar was the turning point in the fight against rinderpest. Around the same time, the head of the UN’s rinderpest campaign, Peter Roeder, had made a crucial discovery about the disease. Using mathematical models of outbreaks, he realized the disease was not spread uniformly but lingered in pockets that served as reservoirs from which larger epidemics occurred. “Before, we thought it was just sprinkled everywhere like stardust,” says Roeder, who eventually became head of the Global Program to Eradicate Rinderpest. “It became quite clear that we had certain areas where the virus was persisting and if we could hit them hard enough, we could eradicate the disease.” He identified five areas: the Afar, Sudan, Pakistan, Yemen, and the Somali ecosystem, which included Somalia as well as parts of Kenya and Ethiopia. The new program targeted those areas, requiring countries to pass a rigorous test to certify they were free of the disease.
In Sudan, that job fell to Bryony Jones, a British veterinarian who in 1997 took leadership of the Tufts effort, now run by the new Feinstein International Center, part of the Friedman School of Nutrition Science and Policy. Complicating matters, Sudan was then in the middle of civil war. Workers couldn’t move after nightfall, when raids often occurred, and they couldn’t hold meetings in the mid-morning, when aerial bombardments often hit. “I remember one meeting we were just finishing and they were scared because the militia was on its way,” says Jones. “The whole village was evacuated. This was something people lived with all the time.” Again, the community workers became an essential part of the effort, able to vaccinate in areas unsafe for the American and European vets. In some cases, the vets sent the workers into a no-go area, dropped off the vaccines by cargo plane, and waited several months until things calmed down before they entered to supervise the work.
The last confirmed case in Sudan occurred in 2000. By the following year, the Tufts vets were retraining community workers to monitor cattle for outbreaks rather than treating them. Once again, the trainers turned to storytelling to explain their mission. Akabwai spun a tale about chasing an enemy who hides out inside a hut. After firing your bullets at him for awhile, at some point you need to stop firing and creep up to see if he is dead. The enemy is rinderpest, he concluded, and the bullets are the vaccines. “It was a very effective way of explaining why you don’t keep vaccinating forever,” says Jones. The logistics of performing a blood survey throughout South Sudan to prove the disease had been eradicated were almost as difficult as the vaccination campaign had been. In the end, though, it showed that rinderpest had been vanquished in the country.
The disease departed each of the afflicted regions without fanfare, observes Mariner. “We would fight, fight, fight,” he says. “And all of a sudden we’d say, ‘Look, it’s gone,’ and it didn’t make any noise when it left.” The last confirmed case of rinderpest in the world occurred in Kenya in 2001, though the disease is thought to have lingered for a few more years in Somalia. The UN remained cautious, waiting for a decade as individual countries performed the necessary cattle surveys to qualify as rinderpest-free.
Finally, on May 25, 2011, the world body declared rinderpest gone at a conference in Paris. Tim Leyland, Jeffrey Mariner, and Berhanu Admassu were there to receive medals for their part in the effort.
In the end, says Mariner, while creating the heat-stable vaccine was important, it was the community health worker program that really made the difference in conquering the disease. “It took two years to make the vaccine, but ten or fifteen years to get it used. Working with people is much more complicated than working in the lab.”
Ultimately it is people who will benefit from the elimination of the disease, not only in the relief of hunger for millions of Africans who rely on cattle herds for their livelihood, but also in the economic boost to poor countries that can now export beef and milk products. In Kenya and Ethiopia alone, according to an African Union analysis, the benefits of rinderpest eradication have already approached $1.4 billion. Less tangible are the benefits of having community health networks that can be used to fight other diseases.
Mariner now works in Kenya, in part attacking another disease called contagious bovine pleuropneumonia, while Admassu and Akabwai are working as field researchers for Tufts’ Feinstein Center in Ethiopia and Kenya respectively, to examine livestock diseases and other issues affecting pastoralists. The techniques they helped pioneer have continued to be used around the world for other diseases, including the H1N1 bird flu in southeast Asia, and a close cousin of rinderpest called peste des petits ruminants (PPR), which strikes goats and sheep. Efforts are already under way to produce a heat-stable version of the PPR vaccine. Recently, the Veterinary Record, the influential journal of the British Veterinary Association, threw down the gauntlet, calling for an international effort to vaccinate against the disease, saying “we believe that another great success could be achieved within a ten-year time frame.”
Rinderpest may be only the second disease in history to vanish from the earth, but if the lessons behind its eradication can be learned, it won’t be the last.
Michael Blanding, a frequent contributor, is a Boston-based writer whose work has been published in The New Republic, The Nation, Consumers Digest, the Boston Globe, and Boston Magazine, where he is a contributing editor. He recently authored a book of investigative nonfiction, The Coke Machine: The Dirty Truth Behind the World's Favorite Soft Drink (Avery/Penguin).