Author: Maria Zagorulya
Institution: University of Rochester
Diseases caused by parasites have had devastating effects on the world’s poorest nations, and the drugs developed by these researchers have had immeasurable health benefits in these regions. This year the Nobel Prize in Physiology or Medicine was awarded for the development of therapies against parasitic diseases. One half of the prize was awarded to Youyou Tu "for her discoveries concerning a novel therapy against Malaria," and the other half to William C. Campbell and Satoshi Ōmura "for their discoveries concerning a novel therapy against infections caused by roundworm parasites."
Mosquitoes infected with the Plasmodium parasite transmit malaria, a disease that causes fevers and brain damage or death in severe cases. Although great efforts have been devoted to eradicate malaria, incidences of the disease continued to increase in the 1960’s and the parasite was gaining resistance against common antimalarial drugs such as chloroquine or quinone. Malaria causes over 450, 000 deaths every year, so it is clear that the development of a new highly potent antimalarial drug is a remarkable contribution to public health. Interestingly, Youyou Tu, Chief Professor at the China Academy of Traditional Chinese Medicine, discovered the active ingredient for the novel antimalarial drug in the ancient texts of traditional Chinese Medicine. After testing a multitude of herbs suggested by ancient Chinese doctors, the scientist found that sweet wormwood, the extracts of the plant Artemisia annua, was highly effective at treating the disease when prepared correctly. After isolating the active ingredient she created a highly potent antimalarial drug Artemisinin, which kills the Plasmodium parasite early in its development.
“The award for Artemisinin is an honor for all Chinese scientists,” Youyou Tu, says conveying an air of deep respect for tradition and ancestral knowledge. As an expert in both Western and traditional Chinese medicine, the scientist views the award as international scientific recognition for the practice of traditional Chinese medicine.
Two other parasitic diseases for which 2015 Nobel Laureates developed a cure for are River Blindness, or Onchocerciasis, and Lymphatic Filariasis. Both diseases are caused by parasitic worms. River Blindness is the second most common cause of blindness, and Lymphatic Filariasis affects over 100 million people causing debilitating diseases of extreme swelling of body parts, such as elephantiasis or lymphedema and scrotal hydrocele.
Satoshi Ōmura, Professor Emeritus at Kitasato, catalyzed discovery of the drug against both diseases when he isolated and cultured thousands of new strains of Streptomyces bacteria producing antibacterial agents. Research Fellow Emeritus William C. Campbell from Drew University built upon Ōmura’s research by investigating anti-parasitic properties of the fifty most promising cultures selected by Ōmura. From these cultures, Irish scientist Campbell identified the bioactive agent Avermectin, which is highly effective against parasites. Avermectin was later developed into the powerful drug Ivermectin, which kills parasite larvae. Both researchers were humbled by the prize; Dr. Ōmura stated that he “merely borrowed the power of microbes”, and Dr. Campbell, who did his work on Ivermectin in a team at Merck, “think[s] of it as an award… [for being] the representative of the Merck company’s research teams.”
Ivermectin and Artemisinin have transformed the treatment of parasitic diseases, saving millions of lives in disease-affected areas. All this is thanks to the hard work and ingenuity of Youyou Tu, William C. Campbell and Satoshi Ōmura, who, in their search for anti-parasite therapies, turned to the world’s greatest collection of wisdom – nature.