UC Davis Magazine Online
Volume 19
Number 4
Summer 2002
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An African Son

An Ethiopian in exile, Tilahun Yilma still wants to relieve suffering in his native country.

By Pat Bailey

Tilahun Yilma (Photo: Debbie Aldridge/UC Davis Mediaworks)

"Our most sacred responsibility is to the next generation of Ethiopians."
— Tilahun Yilma, Ethiopian Review, 1997

Friends and colleagues call him “Yilma.” It was his father’s name and means to germinate and grow.

Tilahun, his first name, means to be an umbrella, provide refuge.

Since his birth, it seems, his life has been woven with the warp and weft of ambition and benevolence, fitting for a man who is both scientist and politician, high-achiever and generous benefactor, American and Ethiopian.

And somehow, threaded throughout the tapestry, has been a deadly cattle disease called rinderpest. Virtually unheard of these days in the western world, it is the source of great suffering and poverty in the fragile developing nations of Africa and Asia.

Yilma, now a professor and microbiologist in the UC Davis School of Veterinary Medicine, first learned of rinderpest from his grandmother who spoke of “Yekebit Elkkit,” the Year of the Annihilation of Cattle. It was in that year, 1888, that Italian troops invading Ethiopia introduced the deadly virus to Africa.

Carried by just three infected cows, rinderpest—meaning cattle plague in German—spread from Ethiopia’s west coast across the Sahel Desert, killing in one year 90 percent of the country’s domesticated cattle, plus countless wild buffalo, giraffe and antelope. An estimated 30-60 percent of Ethiopia’s human population starved to death that year.

Decades later it was rinderpest that brought a young Yilma to UC Davis in 1965 as an undergraduate student, intent on becoming a veterinarian and returning to Ethiopia to combat the disease.

In 1970, with D.V.M. in hand, Yilma joined the international effort to vaccinate Africa’s nomadic herds against rinderpest. For two years, he and colleagues trekked the isolated trails of the nomadic herders along the Ethiopia-Somalia border. The vaccine they administered was effective but impractical for Africa’s rugged conditions. Unstable in the extreme heat, it had to be refrigerated and required syringes, needles and a veterinarian.

More than 125 million cattle were vaccinated during that campaign, and it appeared that rinderpest had been eradicated from Africa. But in 1980 the disease surfaced again in Nigeria, sweeping back across the Sahel all the way to the Red Sea. By then Ethiopia and Somalia were embroiled in warfare, preventing vaccination of livestock to halt the disease.

This time, rinderpest killed an estimated $400 million worth of cattle and caused more than $2 billion in related losses that sapped Africa’s already frail economy. The nomadic herders lost their food supply, and the rinderpest-infected countries were forbidden to sell cattle on the international market.

Despite the failure of the first rinderpest vaccination campaign, Yilma was still intent on conquering the disease when he returned to UC Davis in 1986 as a professor of virology. Intrigued by the potential of the new recombinant DNA technologies, he was convinced that he could develop a rinderpest vaccine for Africa and Asia—one that was simple and inexpensive to produce, easy to administer and would not require refrigeration.

In 1988, after just one year’s work, he announced in the journal Science development of a new genetically engineered vaccine for rinderpest. Although produced through recombinant DNA technology, the vaccine was elegantly simple.

Yilma had identified proteins on the surface of the rinderpest virus that cause an immune response in cattle. He selected the genes that code for two of those proteins, which allow the virus to attach to the cow’s cells and spread from cell to cell. He then plucked those two genes out of the rinderpest virus and nestled them in a weakened form of the vaccinia virus, used earlier to make the smallpox vaccine. This genetically engineered vaccine stimulates the cow’s body to launch an immune response to rinderpest without actually infecting the animal with the disease. If the animal is later exposed to rinderpest, it is already equipped with the antibodies needed to quickly fight off the disease.

The new vaccine proved amazingly powerful in protecting cattle, even when they were injected with 1,000 times a fatal dose of rinderpest. And it met all of Yilma’s criteria for simplicity and heat stability. Requiring no syringes or needles, the vaccine could easily be scratched onto the neck or abdomen of the animal, producing sufficient immune response to ward off the rinderpest virus. Later, the herder could just peel the scab from an animal’s immunization site, grind it up in a saline solution and, from a single calf, have 250,000 additional doses for future vaccinations.
It took just one year to devise the vaccine and another year to move it through animal trials, but it would take the balance of a decade for the vaccine to clear the political hurdles and gain approval for use in Africa.

“It was the first recombinant vaccine to be released in a foreign country by a U.S.-funded researcher, and there was a lot of fear—political fear,” Yilma recalls.

There also was money to be lost by some northerners, particularly the British, whose colonial past left them with a corner on the tropical medicine industry. Yilma still refers to those who tried to obstruct his rinderpest efforts as “the Mafia.”

With a blend of charm, savvy and bulldog tenacity, Yilma maneuvered his way through the regulatory morass. He needed approval not only from U.S. and African officials, but also from international agencies such as the World Health Organization, the Food and Agricultural Organization and the Office Inernationale des Epizooties, an international organization that deals with animal health issues. Even scientists on the biosafety screening committees were leery of the impact a genetically engineered vaccine might have on the environment.

They were also concerned that herders administering the vaccine might accidentally scratch themselves and get a dose of the vaccine, which carried the live, although weakened, vaccinia virus. For people with weakened immune systems, perhaps caused by the AIDS virus, the vaccinia virus that serves as the basis for the rinderpest vaccine might prove lethal, the critics suggested.

Yilma did not share their fears but nevertheless acquiesced and inactivated two of the genes in the vaccine’s vaccinia virus, weakening it enough to prevent any adverse effects for humans. A recent risk-assessment study of the vaccine indicates that the chance of a person being accidentally inoculated with the vaccinia virus is literally about one in a billion.

Finally, in 1993, Yilma received permission to field-test the vaccine in quarantined facilities in both Kenya and Ethiopia. Results from those trials showed that the rinderpest vaccine provided protection for at least 16 months and probably for life.

“Most scientists would have given up,” says Bennie Osburn, dean of the UC Davis School of Veterinary Medicine. “But Yilma persisted, even with all of the international and local politics.”
Grueling as the political battles were, Yilma found in them a certain satisfaction. Though gifted as a scientist, he is equally intrigued by politics.

“I love politics,” he admits from his cramped campus office in Haring Hall.

“Is it true, Lael, that I love politics?” he calls over his shoulder to his assistant. She groans.

To keep up with the global political scene he reads The New York Times, The Economist and Foreign Affairs—“end to end.”

“I tried taking a scientific approach to politics—it was really tough,” he says with a rueful smile. “People are not good scientific animals. They don’t respond.”

His political energies are mainly directed toward Ethiopia, still struggling to establish a stable government. A journalist writing for the Africa News lists Yilma as one of about a dozen “outstanding Ethiopian intellectuals who are making themselves heard on major national issues.”
Ethiopia is currently ruled by leaders from the Eritrean People’s Liberation Front and the Tigrayen People’s Liberation Front, which originated in the northern province of Tigray and the now-independent Eritrea. Recent border conflict has ravaged Ethiopia’s economy. With the average person now earning just $100 per year, it is one of the world’s poorest nations.

"Tribalism destroys Africa—to make it a government policy is an outrageous perversion of democracy."
— Tilahun Yilma, Ethiopian Review, May 1996

To Yilma, the most devastating aspect of Ethiopia’s current political regime is its emphasis on ethnicity, including a policy requiring that school children be taught in their tribal languages rather than Amharic, the official language of Ethiopia.

“We need to teach our children as one Ethiopia,” says Yilma. “Ethiopians speak about 80 different languages. Teaching them in their tribal languages only trains them to hate each other.

“I think in terms of nation, not ethnicity,” he adds. “People should be proud of their own achievements, not just that they belong to a certain ethnic group.”

He is certain the ethnic movement is a veiled effort by Eritrean-based politicians to splinter Ethiopia along tribal lines. In recent years, the country’s constitution was even amended to allow any one of the 65 locally governed tribal homelands to secede from Ethiopia.

Alarmed by the radical tides of Ethiopian politics, Yilma waded into the fray in 1996, drafting a lengthy opinion piece for the Ethiopian Review. The long and derisive article called for Ethiopia to follow the new constitutional trend and secede from the northern provinces of Tigray and Eritrea before they “rip an intact nation apart along ethnic lines.”

So stinging was the article’s effect on Ethiopian politics that four editors from the Ethiopian Review (also known as Tobia) were arrested and jailed. Yilma admits that he spent a good deal of his own money to free the journalists and support their families.

His editorializing was not without personal risk. The U.S. State Department was asked to put a halt to Yilma’s writing. He began to receive death threats and for the first time installed an alarm system in his modest Oak Avenue home in Davis.

His writings continued to appear in various publications, from the African press to The New York Times, well into the late 1990s. These days, his rinderpest work still takes him frequently to Africa, but he has not been back to Ethiopia since 1995 and now considers himself to be in exile.
“I had no political ambition,” he says, shaking his head at the intensity of the reactions to his writings.

"Returning home for many Ethiopians, now living in exile because of the current regime, is a lifelong dream.
— Tilahun Yilma, Ethiopian Review, May 1996

When Yilma thinks of his homeland it is of the pride and dignity of the Ethiopians and neighboring Somalians.

“It is such an old and rich culture,” he says.

At times he toys with the idea of one day building a home on one of the saltwater lakes that dot the Rift Valley in lush, green central Ethiopia. Coffee grows wild there in its namesake province of Kaffa.

But when and if he returns to Ethiopia, it will not be to retire.

“If I were ever to go back to Ethiopia, I would start a program called ‘Wiyiyit,’ which means ‘Exchange of Ideas,’” he says, spelling out the Amharic word on his office whiteboard. It would be an educational project aimed at instilling the idea of personal responsibility.

“I would start with grade-school children and really introduce them to the American work ethic,” he says excitedly, perched on the edge of his desk chair. “I would teach them the love of work.

“The American work ethic is the most incredible thing I’ve seen,” he says. “It starts with parents teaching their children to do chores to earn money.”

A commitment to hard work and achievement is the biggest difference between America and Africa, he is convinced.

“How can a nation really advance?” he asks. “At the end of the day it’s work, isn’t it? And not just for Ethiopia, but all of Africa. The lack of a work ethic is the real cause of poverty.”

He once proposed such an educational radio program to an acquaintance in Ethiopian broadcasting, but his vision was met with little enthusiasm. Even Yilma’s family, including two sisters and a brother who still live in Ethiopia, are puzzled by his drive to make significant changes in his homeland.

“They don’t understand my ‘agenda,’” he says with a smile. He is equally baffled that others in his homeland are not moved to similar action by the extreme suffering in their country. “There is so much disparity. People think only of amassing money,” he says. “There is no sense of giving back.”

Although he does not live extravagantly, Yilma is acutely aware that life has placed him in a privileged position.

“I’m in a very good situation here, and I have the responsibility to pass it to the next generation,” he says. “It is important that you contribute. I can never degrade myself to think that one individual is more important than an entire nation.”

"Democracy, therefore, must be based on individual rights and achievements..."
— Tilahun Yilma, Ethiopian Review, May 1996

Over the years Yilma has devoted his UC Davis laboratory, the International Laboratory of Molecular Biology, not only to research but also to training, with a special emphasis on international students.

He also has worked tirelessly to duplicate the lab overseas so that when Africa’s brightest young minds complete their graduate education in the United States they will have modern research facilities to return to in their home countries. It is Yilma’s personal war on Africa’s “brain drain.” Already one such laboratory has been built with a combination of international and national funds in Egypt, with more planned for Senegal, Kenya, the Ivory Coast and Ethiopia.

He continues to work on the rinderpest front, empowering the African people to fight the devastating disease themselves. In addition to the vaccine, he also has developed an inexpensive, easy-to-use diagnostic test, which will equip African scientists to test animals for rinderpest, distinguishing those that carry antibodies to the virus due to vaccination from those that actually have the disease.

He already has provided diagnostic kits and training on their use to scientists from Senegal, the Ivory Coast, Kenya, Ethiopia and Mali. These students conducted a two-week workshop in Senegal to teach the technology to scientists from more than 30 African countries. Before long, these scientists will be training others in neighboring African and Asian nations.

“They can now produce the kits and set the price for them,” Yilma says. “They are so proud. For so long, scientists from these African nations have been made to feel so inferior.”

The International Atomic Energy Agency, which has funded Yilma’s rinderpest diagnostic research because it uses nuclear technology for a peaceful purpose, is also pleased.

“Yilma has done what many have called for . . . but which few have done,” writes Thomas Tisue from the agency’s headquarters in Vienna. “He has brought the resources of a top-rank ‘northern’ research facility to bear on problems that are major constraints only in developing countries. “Thus, he has created . . . a unique opportunity to help Africa free itself of dependence on expensive reagents from outside the region, while also empowering Africans to wrest leadership roles and decision-making away from Northern European and North American elites,” he adds. “He is a shining example of what is needed: commitment, knowledge and a degree of selflessness.”

Rinderpest is still prevalent in African nations like Somalia and Sudan, which are experiencing civil strife, and in a number of Asian countries. It also persists in the wildlife population, but Yilma is confident that alfalfa pellets laced with an oral vaccine and distributed in the wild will eventually take care of that problem.

Meanwhile, his research has moved on to the search for a vaccine for HIV, the virus that causes AIDS. The human disease is proving to be a more formidable opponent than rinderpest, but Yilma is not discouraged.

“There is a lot of interesting basic immunology that has already come out of the AIDS vaccine research,” he says. He is sure that eventually AIDS will be defeated, but perhaps not by a vaccine.

“You never know what new technology will come along,” he says. “Maybe it will take something entirely new—the equivalent of antibiotics and vaccines—that will work against HIV.”

He speaks with the confidence and serenity of one who has already successfully cleared many of life’s hurdles. Just two years shy of 60, he remains fit and trim by swimming, skiing and bicycling.

“We affectionately call him the Ethiopian yuppie,” says Kelly Nimtz, director of the veterinary school’s development office, who frequently joins Yilma and others from the school on long-distance bike rides to the coast or into the Sierra. “He likes good food, good wine and was the first to get the bike model that Lance Armstrong rode in the Tour de France,” says Nimtz. “And yet he is extremely, extremely generous and very supportive of his students. “He really is a role model for how to bridge the cultural gap between Africa and the United States.”

Yilma has been recognized on campus for his achievements in both teaching and research. This spring he received the Faculty Research Lecturer Award, the highest honor that UC Davis faculty members confer on their colleagues.

Upon receiving the award, Yilma seemed genuinely touched that anyone should be aware of, much less honor, his efforts. After all, hard work, whether in the lab, the classroom or the editorial pages, is all part of giving back. It is what one individual can reasonably do to strengthen the whole.

“We have an old Ethiopian proverb,” he says. “The mutiny of a bunch of threads will restrain a lion.”

Pat Bailey writes about agriculture and veterinary medicine for the UC Davis News Service.


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