Published 5 October 2015 by Susanne Dambeck

Nobel Prize 2015: The Fight Against Tropical Parasites

This year’s Nobel Prize in Physiology or Medicine emphasises scientific breakthroughs that have been applied with great success in tropical medicine. “The two discoveries have provided humankind with powerful new means to combat these debilitating diseases that affect hundreds of millions of people annually,” the Nobel committee in Stockholm announced today. And these diseases mostly effect “the most vulnerable” – children in developing countries.


  Youyou Tu, who discovered a higly efficient malaria drug, was born in 1930 and studied pharmaceutical sciences in Beijing, graduating in 1955. She also trained in traditional Chinese medicine. During China’s so-called Cultural Revolution starting in the mid-1960s, working as an academic was almost impossible, with imprisonment, torture and displacement being ubiquitous. But at the same time, the Vietnam War was raging, and malaria was a huge problem for both sides. It was also a major cause of death in southern Chinese provinces. Thus Mao Zedong started the secret military ‘Project 523’ to find an effective malaria treatment, because the parasite Plasmodium was becoming increasingly immune to other substances. Youyou Tu became part of this secret project. After being dissatisfied with the substances she found, she studied more than 2000 ancient manuscripts of traditional Chinese remedies and found that many anti-malaria drugs included the plant Artemisia annua. Tu and her team made 380 herbal extracts and tested them on mice. One of the compounds did indeed reduce the number of malaria parasites in the blood. Next, Tu isolate the active agent ‘artemisinin’ and tested it first on herself. Today, artemisinin-based combination therapies are recommended by the WHO as the most effective malaria treatment; the combination with other agents is necessary to prevent artemisinin resistances. When Tu started her malaria research, her husband was in a labour camp and she had to give their only child to a nursery to study malaria in the southern Chinese province of Hainan. When she came back, her daughter did not recognise her and cried when she tried to take her home: “The work was the top priority, so I was certainly willing to sacrifice my personal life,” she commented later. Tu is the twelfth woman to win the Nobel Prize in Medicine, she will receive half of the eight million Swedish crowns (about 850,000 Euros).  


Satoshi Ōmura is a Japanese biochemist who studied bioactive chemicals derived from naturally-occurring microorganisms. In the 1970s, he was searching for new strains of Streptomyces bacteria in Japanese soil probes. Ōmura characterised thousands of Streptomyces cultures and selected a few that were most promising in the fight against harmful microorganisms. One of them was ‘Streptomyces avermitilis’, the source of Avermectin, isolated in 1978. During his career, Ōmura has discovered more than 400 active substances, among them novel antibiotics and anti-cancer drugs.

Helminths are worm-like parasites that seriously affect their host’s health. The Nobel Prize committee focused on Elephantiasis and river blindness as two severe diseases. But the various helminth species can cause many different diseases and conditions, always weakening the hosts’ health and immune system, making learning difficult and exacerbating syndromes like HIV, tuberculosis or malaria. More than one billion people are estimated to be infected with helminths, the vast majority live in developing countries.


  Back to the year 1978: William C. Campbell, an Irish-born US biochemist, was able to acquire the Streptomyces probes from Ōmura. Campbell was working for the Merck Institute of Therapeutic Research in New Jersey at the time. He was able to show that Streptomyces avermitilis was especially effective against roundworm infections in farm animals. Avermectin was later modified into the more effective compound Ivermectin. This substance was later tested on humans with parasitic infections, and it proved to kill the parasites larvae very effectively – so effectively that both river blindness and Elephantiasis could be eliminated in the near future. Campbell is now an Emeritus research fellow at Drew University in Madison, New Jersey, Ōmura is a Professor Emeritus at Kitasato University.  


The Nobel committee concluded: “Campbell, Ōmura and Tu have transformed the treatment of parasitic diseases. The global impact of their discoveries and the resulting benefit to mankind are immeasurable.”



Congratulations, and we are looking forward to inviting the new Nobel Laureates to Lindau!

Pictures used in slider graphic: Ⓒ Nobel Media AB 2015

Susanne Dambeck

Susanne Dambeck is a science writer in English and German, and author of several nonfiction childrens' books. A political scientist by training, she has worked in politics, television and as a biographer. Apart from scientific findings, she is interested in people and in storytelling in different languages.