Nobel Prize! Drugs to take on parasites bring home the award!

As you may or may not have heard, the winners of the Nobel Prize for Medicine and Physiology were announced today, and a total of three scientists received this award: Satoshi Ōmura (a Japanese microbiologist), William C. Campbell (an expert on parasite biology), and Youyou Tu (a Chinese medical scientist and pharmaceutical chemist). But more important than who they are, is what they achieved, and each of these great minds has somehow contributed immensely to the treatment of infections caused by some nasty parasites.

Both Ōmura and Campbell contributed to the discovery of a new drug that is extremely effective in killing Microfilariae larvae; an organism known to cause Onchocerciasis, or River Blindness as it might be known to us laymen. The story begins with Ōmura, described as an expert in isolating natural products, deciding to focus on a particular group of bacteria known as Streptomyces. These bacteria are known to produce many compounds with antibacterial properties when isolated, including Streptomycin, the drug initially used to treat Tuberculosis. Ōmura, using his biological powers, successfully isolated and cultivated new strains of Streptomyces, and from thousands of cultures, he selected the 50 best candidates that merited further analysis. One of these turned out to be Streptomyces Avermitilis.

Skip forward a bit, and we see that Campbell acquired some of these samples and set about exploring their antibacterial efficiency. He was then able to show that a component produced by Streptomyces Avermitilis was very efficient against parasites in both domestic and farm animals, which he then purified and named Avermectin. This was initially used as a veterinary drug given Campbell’s findings, but subsequent modification on the molecular level (an addition of only two hydrogen atoms!) gave us the “wonder drug” Ivermectin. This was then shown to out-perform the previously used DEC (Diethylcarbamazine for the chemistry nerds) primarily due to the lack of side effects such as inflammation. This has made the drug extremely safe for human use, allowing it to be administered to patients by non-medical staff and even individuals in small rural communities with no hospital experience at all (provided some very basic training). This is what makes this drug so special, as it can be safely used in some less developed parts of Africa and South America, where River Blindness is most common and advanced medical care may be unreachable or unaffordable for some individuals.

The other major advancement in this field worthy of the Nobel Prize was the work of Youyou Tu, who developed an effective treatment for another well-known parasitic infection: Malaria! Inspired by traditional Chinese medicine, she identified an interesting extract from the plant Artemisia Annua, or as you may know it, Sweet Wormwood. Despite initial results appearing inconsistent, Tu revisited some literature and found clues that lead to the successful extraction of the active component, Artemisinin. She then became the first to demonstrate that this compound was highly effective against Malaria, killing the parasite at even early stages of development. While the precise mechanism of how Artemisinin achieves this is still debated, many of the current theories and hypotheses are that the drug forms a highly reactive compound within the Malaria organism which is then capable of irreversibly modifying and damaging proteins and other important molecules, and the parasite goes down!

The consequences of these discoveries have been felt across the globe, but the countries most affected by these diseases stand to gain the most. River Blindness is nowhere near the huge problem it used to be, with treatment scenarios moving away from control and into eradication and elimination. This could be MASSIVE for the global economy, with estimates stating a potential saving of US$ 1.5 billion over a few decades! Eradication could also be great for local economies; as such serious illnesses can affect employee attendance, due to actual infection or having to care for a relative. This decrease in workforce can potentially lead to an economic downturn and further unemployment. When combined with the more direct costs of treatment, the losses can be huge. Malaria alone is thought to cost Africa around US$ 12 million a year in lost GDP, and continues to slow growth by more than 1% each year. Just imagine what eliminating these diseases could do for these countries. Not only could their economies rise to a more globally competitive level, it could also lead the way to alleviating the more poverty-stricken areas. Families would be freer to go out and earn a living, with no need to worry about potential infection or having to care for sick family members. This could afford more food, better healthcare, and leisure activities, drastically increasing quality of life. Granted it would also cause significant population growth in areas with already high birth rates, and the current food crises would not be helped by this, but these problems would be easier to control and solve in a disease-free society.

That is not to say there are no concerns associated with disease eradication, although it is extremely unlikely that these would out-weigh the benefits. It could be that the process of natural selection would be halted, as these diseases weed out weaker immune systems in the population. But with advances in technology and medicine allowing for new treatments of both genetic and infectious diseases, if such a thing could happen, the causes are already present across the globe, so why should it influence our decision in this case? I mean, Malaria was eradicated in the US many years ago and there have been no obvious downsides to this. You could also look at the example of smallpox, which not only saved the world around US$ 1.35 billion a year, but has had no clear effect on our immune systems. Even if it were to have such an effect, it would take many thousands of years for such a change to occur, and it is possible that our technology and medical treatments will have advanced enough to counter this. While this question does remain to be answered, there is no evidence of a decline in our immune systems, and I think it is safe to say that the benefits of eliminating these diseases would go way beyond the realm of public health. So should we let a completely hypothetical downside influence our decision? Answer! No we shouldn’t.

Sources:

The Key Publications mentioned by the Nobel Assembly at Karolinska Institutet:

  • Burg et al., Antimicrobial Agents and Chemotherapy (1979) 15:361-367
  • Egerton et al., Antimicrobial Agents and Chemotherapy (1979) 15:372-378.
  • Tu et al., Yao Xue Xue Bao (1981) 16, 366-370 (Chinese)
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