Parasites are a tremendous burden on global health, killing more than a million people each year; a mere fraction of the number they infect and cause disease in. Parasitic infections also disproportionately affect those residing in developing countries, largely due to the fact that most of the world’s poorest nations lie within the tropics, where these parasitic organisms are abundant.
Needless to say, finding ways to combat these diseases is imperative if we want to improve global health. And that’s why the achievements of three eminent scientists working within this field are being heralded this week, in the form of the Nobel Prize in Physiology or Medicine.
The prestigious award is being shared this year, with one half going to William C. Campbell and Satoshi Ōmura, and the other to Youyou Tu. Both concern discoveries that have helped toward the development of new therapies for parasitic disease, but the agents and the infections themselves are vastly different.
Campbell and Ōmura’s drug, Avermectin, has ultimately contributed to a significant decline in cases of two diseases caused by helminths – parasitic worms that plague around one third of the world’s population. These diseases are lymphatic filariasis, often called elephantiasis, and river blindness, both of which are caused by roundworms.
Although the former is rarely fatal, it can cause disfiguring and debilitating swelling of body parts and thus not only creates a huge economic strain due to disability, but also leads to social problems from stigma. River blindness, as the name suggests, can lead to impairment or loss of vision, alongside skin disease that comes with it horrific chronic itching.
Two pretty nasty diseases, to say the least, but thanks largely this duo of researchers, fewer people are suffering each year. Ōmura’s contribution came in the form of laboriously screening strains of Streptomyces bacteria, a group renowned for the antimicrobial agents they produce.
After selecting the most promising candidates, Campbell then explored them further and ultimately honed in on one that demonstrated remarkable activity against parasites from a range of animals. This compound, Avermectin, was later chemically modified for improvement, resulting in a novel class of drugs that are remarkably effective against these devastating diseases.
If you hadn’t heard of either of these lesser-known infections, you’ll definitely know about the disease Tu’s research concerns: malaria. It doesn’t need much of an introduction, what with there being around 200 million cases each year and about half a million deaths. But again Tu’s work has been instrumental in reducing those figures, having ultimately brought to us a class of drugs that remain the fastest acting and most effective antimalarial agents to date.
Tu’s work has its roots in traditional Chinese herbal medicine, where a plant called Artemisia annua had received a lot of attention as a promising candidate against the malaria parasite, Plasmodium falciparum. Extracts from the plant failed to produce consistent antimicrobial effects, but Tu eventually managed to isolate and purify the bioactive compound from the plant, demonstrating its efficacy in both humans and animals. Eventually named Artemisinin, this has led to a whole group of extremely potent medications that are regarded a cornerstone in malaria treatment.