Explaining The 2015 Nobel Prize in Medicine: Parasites

Parasites don’t have a very good reputation between people. They are a group of nasty little fellows who affect world’s poorest countries – mainly Africa and South Africa. Some common examples of parasitic diseases are scabies, headlice and ascariasis. There is one parasite though that gets the number one place – Plasmodium. Infection with plasmodia is known as malaria, a disease which takes approximately 600 000 lives every year.

Given the global burden of these aillments, this year the Nobel committee decided to reward three scientists responsible for discovering novel therapies against some of the deadliest parasitic diseases. One half of the prize went to William Campbell and Satoshi Ōmura for their discovery of a therapy against infections caused by roundworm parasites, while the other half went to a Chinese female scientist named Youyou Tu, who discovered a therapy against the so deadly Malaria.

In 1969, Youyou Tu began the search for a drug that could cure malaria. Up until then, Malaria was being treated with chloroquine or quinine, but the resistances to these drugs were growing each year, making them almost useless. Youyou Tu was a researcher at the Academy of Traditional Chinese Medicine, so it was plain as day to her that the answer would be hidden somewhere in Nature. She decided to test a myriad of herbal remedies, finding out that Artemisia annua could be a potential candidate. The results weren’t the best at first, but once she found out how to extract the active component of the plant, the results couldn’t be better. To make sure the molecule, now known as artemisinin, was safe for humans, she, along with her colleagues, took the extract themselves! They later did clinical trials, establishing artemisinin as a new antimalarial drug. Following the introduction of this drug in the market, the mortality rate of Malaria declined abruptly. More than 100 000 lives in Africa alone are estimated to be saved each year thanks to this drug. This succession of events convinced the Nobel committee to award Youyou Tu with a prize this year for her astonishing work in the late 1960s.

The other half of the prize was awarded to Campbell and Ōmura. In the late 70s, Ōmura focused his attention to Streptomyces, a bacteria which likes to dwell in the soil. This bacteria was known to produce streptomycin, an antibiotic used against tuberculosis, so Ōmura probably thought he could find something else interesting about these little guys. From thousands of different cultures, he selected about 50 of them, which were later sent to William Campbell, an American parasite expert. Campbell found that Streptomyces avermitilis (which he named) was able to produce avermectins, which worked as antiparasitic agents by blocking nervous conduction. In 1980, they selected ivermectin to treat nematode and arthropod infections. Today, ivermectin is freely available virtually everywhere and is the best weapon against River Blindness (a disease caused by Onchocerca volvulus) and filariasis (caused by thread-like worms).

This year was a triumph for both Parasitology and Traditional Medicine. The combined efforts of Campbell and Ōmura and the persistence of Youyou Tu helped save literally millions of lives across the globe. One thing one can not help but to notice is the lack of recognition Tu was given following her discovery. Despite her notable achievement, she remains unknown both in the eyes of the general public and scientists. I can’t help but to ask myself: is it because she is a woman?


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