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NORTH ANDOVER, Mass. — When biologist William Campbell answered the phone before dawn on Monday, he was startled to hear a reporter telling him he had just been awarded the Nobel Prize. In his confusion, he ended the call abruptly.

A moment later, Campbell called the reporter back.


“I said, ‘It’s not that I mistrust you, but is there some way that I can verify this?’” Campbell recounted in an interview with Stat at his home in a retirement community.

The reporter directed him to the Nobel website, where Campbell found his verification: He was a corecipient of the 2015 prize for physiology or medicine.

Campbell, 85, and biochemist Satoshi Omura of Japan share half the prize for their work to develop ivermectin, a drug combating parasites that cause two debilitating diseases, river blindness and lymphatic filariasis. In severe cases, the latter can develop into the condition elephantiasis, which causes swelling of the limbs.


The other half of the award was given to Chinese scientist Youyou Tu, who scoured ancient Chinese texts looking for a traditional remedy for malaria. She focused her efforts on a plant called sweet wormwood, or Artemisia annua. The result: artemisinin, a first-line drug therapy and a lifesaver.

In both cases, the award honors work that was done decades ago. In the intervening time, the two drugs have benefited hundreds of millions of people.

“I was immensely relieved that it works in humans and at a low dose and seems to be very safe.”

William Campbell

“These three scientists have had a massive positive impact on global health. This was a great choice by the Nobel Committee,” said Dr. Christopher V. Plowe, president of the American Society of Tropical Medicine and Hygiene.

In the case of ivermectin, the discovery is only half of an incredible story. When Campbell realized his team at Merck & Co. Inc. — his longtime employer — had a drug that could treat infections with debilitating parasites, he and others also quickly realized that the people who needed the drug could not afford to pay for it.

A collection of microscopes in the home of William C. Campbell in North Andover, Mass. Mary Schwalm/AP

He and his boss talked to Dr. Roy Vagelos, then the chief executive of Merck, who made the bold decision to donate the drug — as much as was needed for as long as was needed — to groups working to control river blindness. Later, the free supplies were extended to combat filariasis.

“It was a gutsy move. It’s a very difficult thing to give a drug away,” said Campbell.

He said at the time there was concern that other drug companies might stop working on therapies for diseases that afflict the world’s poor if they felt they, too, would be expected to give them away.

It did create a precedent, but not the one Merck feared, said Craig Withers, acting vice president of health programs at the Atlanta-based Carter Center, which has been instrumental in the work to fight river blindness, formally called onchocerciasis, and filariasis.

In fact, Withers said, the Merck decision gave birth to the effort to combat what are known as neglected tropical diseases.

SmithKline Beecham (now GlaxoSmithKline) later gave away the drug albendazole, which is also used to treat filariasis, and Pfizer donated the antibiotic azithromycin for the treatment of trachoma, a bacterial infection that can also cause blindness.

Merck, which produces the antiparasite drug under the brand name Mectizan, has donated more than 1 billion treatment courses of the drug to 28 countries in Africa, six in Latin America, and to Yemen.

Four countries in Latin America have been able to arrest transmission of river blindness using the drug and other countries are making inroads against the disease, Withers said.

The ivermectin discovery was accidental, Campbell admitted.

Omura, a microbiologist who specializes in isolating natural compounds, sent Merck soil samples for bacterial research. But the freeze-dried samples sat on a shelf in the microbiology department for a year.

William Campbell in his North Andover home. Suzanne Kreiter/The Boston Globe

When Campbell and his colleagues in the parasitology department later came up with a new method for testing potential compounds against parasitic worms, the soil samples were tested.

To his astonishment, the samples contained a compound that paralyzed parasitic worms. That substance was named avermectin, which was later modified and named ivermectin.

Campbell and a team at Merck tried the compound on rats, mice, guinea pigs, dogs, ferrets, and even reindeer before testing it on humans. Those clinical trials proved the drug was effective.

“When you work with new drug discovery, you accept the fact that most of what you work on doesn’t lead to a successful drug,” Campbell said. “I was immensely relieved that it works in humans and at a low dose and seems to be very safe.”

Campbell said the Nobel honor belonged not just to him, but to the entire team at Merck. “I did very little,” he said, “but the little things I did do had big effects.”

A native of Ireland, Campbell has been interested in parasites since he was a teenager growing up in a small town in County Donegal, where his father raised livestock. He worked for decades at the Merck Institute for Therapeutic Research.

Campbell retired to a former dairy farm in North Andover about five years ago, in part to be near a daughter in New Hampshire.

Campbell, Omura, and Tu share prize money of eight million Swedish kroner, or about $960,000. Their awards will be presented at a gala in Stockholm on Dec. 10.