A former Merck & Co. scientist is sharing the Nobel Prize in medicine for helping to discover a treatment for two parasitic diseases that have stricken millions in the developing world.

William C. Campbell, 85, who later became a faculty member at Drew University in Madison, N.J., will get the award in Stockholm, Sweden, on Dec. 10 along with Satoshi Omura, a professor emeritus at Kitasato University in Japan.

The two each will receive about $240,000 for their success in combating river blindness, caused by a parasite transmitted through the bite of river-dwelling black flies, and elephantiasis, marked by severe swelling and disfigurement of the limbs. The same drug, ivermectin, works on both, and was derived at Merck from a compound that Omura and colleagues had isolated from a soil sample taken near a Japanese golf course.

Their award represents half of the overall $960,000 prize in medicine. The other half goes to Youyou Tu, a professor at the China Academy of Traditional Chinese Medicine, for her discovery of a treatment for malaria.

But the Nobels, widely considered the world's top prizes in academia, are much more about prestige than money. So momentous is the honor that Campbell, who now lives in North Andover, Mass., did not believe the news - delivered Monday via early-morning phone call from Sweden.

"When I heard it, I said 'You must be kidding,' " Campbell said Monday afternoon in a phone interview. "I called the guy back and asked if there was a way I could verify it. He told me how I could go online."

Campbell said it made sense for the prize committee to recognize efforts to fight parasitic diseases. In particular, the world's campaign against the parasitic worms that cause river blindness, for which Merck has donated billions of doses, is considered one of the most dramatic success stories in public health.

But Campbell said the credit should go to many, not just him.

"It's certainly not something I ever dreamt of," he said. "I consider myself a representative of that group."

Former students at Drew remembered Campbell fondly Monday in posts on social media. After spending 33 years at Merck, the native of Ireland was a research fellow at the university from 1990 to 2010, supervising the research of undergraduates.

He also taught an advanced seminar in parasitology, helping students to remember facts by reciting his own funny poems on the subject.

Elena Tartaglia, a 2005 graduate who now teaches biology at Bergen Community College in New Jersey, recalled one Campbell poem about worms that rhymed monoecious - which means an organism with both male and female characteristics - with specious.

"It's over 10 years ago, and I still remember things from this course," Tartaglia said. "He made things really memorable."

David Cennimo, another former student who is now an assistant professor at Rutgers New Jersey Medical School in Newark, said he strives to emulate Campbell's teaching style.

"He's that type of teacher that I've always wanted and tried to be," Cennimo said. "He could explain things. Not just lecture, but really explain so that you understood them."

Like Tartaglia, Cennimo took the parasitology seminar. He said Campbell did not call attention to his own achievements, so the course was halfway over before students realized their professor was a big deal.

"He would make you feel like your opinion was just as valued as his," Cennimo said.

An infectious disease specialist, Cennimo sometimes prescribes ivermectin, the very drug Campbell helped discover, to treat parasitic diseases in immigrants who came to the Newark area from developing countries. It has proved to be effective against a variety of such diseases, in addition to river blindness and elephantiasis.

Campbell's original mission while at a Merck lab in Rahway, N.J., was to work on drugs for deworming livestock, in partnership with Omura and others. The arrangement grew out of Omura's ties to a former Merck scientist for whom he had worked as a visiting scientist at Wesleyan University.

In 1978, when a derivative of the compound from Omura's soil sample proved effective against a worm that infected horses, Campbell realized a related kind of worm was responsible for river blindness.

So he proposed studying the drug's impact on humans, and by 1981 Merck was conducting Phase 1 trials in Senegal and with West African immigrants in Paris.

With few to no side effects, the drug eliminated the parasite with just one dose, given orally once or twice a year. It later was shown to be effective against elephantiasis as well, and Merck agreed to donate it to developing countries. The company also has sold it for use in livestock.

Campbell retired from Drew in 2010 but still lectures there occasionally. He also has acted in community theater, and he paints the roundworms and other parasites that he spent decades studying.

Vincent Gullo, another Drew research fellow who also worked with Campbell at Merck, recalled one painting that reimagined worms as flowers, arrayed attractively in a vase.

"He used the worms as inspiration," Gullo said.