Nobel Prize in Physiology or Medicine 2015 (Part 1 of 2)


On Monday October 5th, less than 2 weeks ago, the Nobel Committee awarded the 2015 Nobel Prize in Physiology or Medicine to two groups of scientists for two different discoveries; William C. Campbell and Satoshi Ōmura “for their discoveries concerning a novel therapy against infections caused by roundworm parasites” and Youyou Tu “for her discoveries concerning a novel therapy against Malaria”. Campbell and Ōmura will split half of the prize among themselves (approximately $250,000 each) while Tu will receive the other half of the prize (approximately $500,000). In this post I’ll focus on Campbell and Ōmura’s discoveries and in my next post I’ll discuss Tu’s discoveries.


Roundworms, also known as nematodes, are parasites that can use humans, dogs, and cats as hosts. In humans, they typically enter the body through the mouth (though they can also enter through the skin) and travel to the intestines. Roundworms are responsible for a variety of illnesses and diseases, including elephantiasis and river blindness; elephantiasis is caused by the roundworm Wuchereria bancrofti entering the body’s lymphatic system, while river blindness is caused by the roundworm Onchocerca volvulu travelling to the eye. Both elephantiasis and river blindness tend to target rural populations in developing countries who aren’t likely to have access to extensive medical care. This is why having an effective, affordable drug against elephantiasis and river blindness is so important.

In Japan, Satoshi Ōmura collected and cultured samples of the bacteria Streptomyces avermitilis from soil and sent them off to William C. Campbell in New Jersey. Campbell then fed samples of the bacterial culture to mice infected with roundworm and found that the Streptomyces avermitilis samples killed virtually all of the roundworms in the mice it was fed to. Campbell purified the bioactive substance in Streptomyces avermitilis that was killing the roundworms and named it avermectin, which was further modified to produce ivermectin.

The chemical structure of ivermectin.

Perhaps what’s most surprising about avermectin and ivermectin is that they’ve not been patented by a drug company, meaning both drugs are available across the globe at a highly affordable price. This is great news, especially for the over 150 million people in developing countries who are currently infected with roundworms. In fact, the highly reasonable price of ivermectin around the world is why over 200 million people were able to take it last year alone.

If you want to learn more about Campbell and Ōmura’s work be sure to watch the Nobel Committee’s official announcement video and if you want to learn more about the laureates you can head over to the Nobel Prize website. Stay tuned next week for my post on Youyou Tu’s work and how it’s helping lead the fight against malaria.


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