Japanese microbiologist Satoshi Omura on Monday shared this year’s Nobel Prize in medicine for his work on a therapy for debilitating diseases caused by parasitic worms.

The 80-year-old Omura, a professor emeritus of Tokyo’s Kitasato University, shared the honor with William C. Campbell of Drew University in New Jersey and Youyou Tu of the China Academy of Traditional Chinese Medicine.

“I’m surprised. I never thought I would win” the prize, Omura reportedly told his daughter Monday evening by phone.

At a news conference Monday evening at Kitasato University, Omura humbly praised microorganisms for his award. “I was helped by microorganisms. I wonder if I deserve the prize,” he said.

Campbell, a retired scientist who spent 33 years at the pharmaceutical company Merck and now lives in North Andover, Massachusetts, also said the award came as a huge surprise.

“It was a great team effort by the people at Merck and Company,” he said.

The Nobel committee honored Omura and Campbell for their work on the drug avermectin, derivatives of which have radically lowered the incidence of river blindness and lymphatic filiarisis, commonly known as elephantiasis.

Tu was honored for her work on artemisinin, a drug that has helped significantly reduce the mortality rates of malaria patients.

“These two discoveries have provided humankind with powerful new means to combat these debilitating diseases that affect hundreds of millions of people annually,” the committee said in its citation. “The consequences in terms of improved human health and reduced suffering are immeasurable.”

Avermectin is used to control parasitic worms, which affect one-third of the world’s population and are especially prevalent in South Asia, Africa and Central and South America, the Nobel body said.

It added that Omura’s work was a breakthrough after decades of limited progress in developing durable therapies for parasitic diseases.

Equipped with “extraordinary skills,” Omura developed new techniques for the large-scale culture of certain bacteria and isolated strains that he found to be effective against the worms, the statement said.

Campbell then acquired Omura’s cultures and further explored their efficacy.

Nobel committee member Hans Forssberg said the work has helped to reduce dramatically the number of individuals affected each year from “the stigmatizing and disabling symptoms” of river blindness and elephantiasis.

“By allowing children to go to school and adults to go to work the treatment helps them to avoid poverty and contributes to an economic boost in society,” he said.

The Nobel Assembly at Karolinska Institutet in Stockholm, which administers Nobel Prizes, said: “Treatment is so successful that these diseases are on the verge of eradication, which would be a major feat in the medical history of humankind.”

The last time a Chinese citizen won a Nobel was in 2012, when Mo Yan got the literature award. But China has been yearning for a Nobel Prize in science. This was the first Nobel given to a Chinese scientist for work carried out within China.

“This is indeed a glorious moment,” said Li Chenjian, a vice provost at prestigious Peking University. “This also is an acknowledgement to the traditional Chinese medicine, for the work began with herbal medicine.”

Information from AP added