Mr. Campbell and Mr. Omura won it for "their discoveries concerning a novel therapy against infections caused by roundworm parasites", while Ms. Tu won it for "her discoveries concerning a novel therapy for malaria."

Mr. Campbell and Mr. Ōmura discovered a new drug, Avermectin, the derivatives of which have radically lowered the incidence of River Blindness and Lymphatic Filariasis, said a press relase. "The drug also showed efficacy against an expanding number of other parasitic diseases," it added.

Youyou Tu discovered Artemisinin, a drug that has significantly reduced the mortality rates for patients suffering from Malaria.

“The 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. “The consequences in terms of improved human health and reduced suffering are immensurable.”

Campbell is a research fellow emeritus at Drew University in Madison, New Jersey. Omura, 80, is a professor emeritus at Kitasato University in Japan and is from the central prefecture of Yamanashi. Tu is chief professor at the China Academy of Traditional Chinese Medicine.

The medicine award was the first Nobel Prize to be announced. The winners of the physics, chemistry and peace prizes are set to be announced later this week. The economics prize will be announced next Monday. No date has been set yet for the literature prize, but it is expected to be announced on Thursday.

The winners will share the 8 million Swedish kronor (about $960,000) prize money with one half going to Campbell and Omura, and the other to Tu. Each winner will also get a diploma and a gold medal at the annual award ceremony on Dec. 10, the anniversary of the death of prize founder Alfred Nobel.

Last year’s medicine award went to three scientists who discovered the brain’s inner navigation system.