On October 5, 2015 one half of the Nobel Prize for Physiology and Medicine was jointly awarded to William C. Campbell and Satoshi Ōmura for their discoveries concerning a novel therapy against infections caused by roundworm parasites. The research of Campbell and Ōmura has led to the development of drugs to effectively treat diseases caused by roundworm parasites, to include lymphatic filariasis, which is the primary cause for lymphedema worldwide.
This painful and extremely disfiguring disease has been identified by the World Health Organization (WHO) as a leading cause for permanent and long-term disability in the world. It is a tropical disease, endemic to more than 80 regions in Africa, India, Southeast Asia, and South America, as well as in the Pacific islands and the Caribbean. Lymphatic filariasis is rare in the United States, but may be contracted by visiting endemic regions.
Lymphatic filariasis is transmitted to humans by different types of mosquitos that carry infective-stage larvae and bite an individual. During the bite, the larvae enter the wound and are deposited in the individuals’ skin; from there the parasitic larvae migrate to the lymphatic system, where over a period of 6-12 months they develop into adult worms and mate.
The drug Ivermectin kills the first larval stage of the parasite – the babies of adult female worms.
The press release on the official website of the Nobel Prize (www.nobelprize.org) describes the discovery as follows (excerpt):
“Satoshi Ōmura, a Japanese microbiologist and expert in isolating natural products, focused on a group of bacteria, Streptomyces, which lives in the soil and was known to produce a plethora of agents with antibacterial activities (including Streptomycin discovered by Selman Waksman, Nobel Prize 1952). Equipped with extraordinary skills in developing unique methods for large-scale culturing and characterization of these bacteria, Ōmura isolated new strains of Streptomyces from soil samples and successfully cultured them in the laboratory. From many thousand different cultures, he selected about 50 of the most promising, with the intent that they would be further analyzed for their activity against harmful microorganisms.
William C. Campbell, an expert in parasite biology working in the USA, acquired Ōmura’s Streptomyces cultures and explored their efficacy. Campbell showed that a component from one of the cultures was remarkably efficient against parasites in domestic and farm animals. The bioactive agent was purified and named Avermectin, which was subsequently chemically modified to a more effective compound called Ivermectin.
Ivermectin was later tested in humans with parasitic infections and effectively killed parasite larvae (microfilaria) (Figure 3). Collectively, Ōmura and Campbell’s contributions led to the discovery of a new class of drugs with extraordinary efficacy against parasitic diseases.”
The discovery of Avermectin and the effectiveness of this drug on parasitic diseases have radically changed the treatment approach to these debilitating conditions and provided humankind with powerful new means to combat these debilitating diseases that affect hundreds of millions of people annually. The consequences in terms of improved human health and reduced suffering are immeasurable.
Thank you Mr. Campbell and Mr. Ōmura!