Anti-parasite Drugs and the Nobel Prize for Medicine

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The 2015 Nobel Prize in Physiology or Medicine was announced earlier this week [1]. The prize was awarded to three scientists who developed therapies by looking at natural, local substances, against parasitic infections.

The prize of 8-million-Swedish-krona ($1.2-million USD) was divided, with one half jointly to Drs. William C. Campbell, age 85, at Drew University in Madison, New Jersey, USA, and Satoshi Omura, age 80, at Kitasato University in Tokyo, Japan, for their work on a novel therapy against infections caused by roundworm parasites, and the other half to Dr. Youyou Tu, age 85, at the China Academy of Traditional Chinese Medicine in Beijing, China, for her work on a novel therapy against Malaria.

Parasitic infections are a major global health problem

Parasitic infections are a global health problem of unbelievable magnitude. Two out of three people worldwide are afflicted with a parasitic disease, and most people who harbor parasites actually are afflicted with a range of diseases.

The Nobel Assembly at Karolinska Institutet in Sweden said in a statement [1]:

Diseases caused by parasites have plagued humankind for millennia and constitute a major global health problem. In particular, parasitic diseases affect the world’s poorest populations and represent a huge barrier to improving human health and wellbeing. This year’s Nobel Laureates have developed therapies that have revolutionized the treatment of some of the most devastating parasitic diseases.

Ascariasis, a disease caused by the parasitic roundworm Ascaris lumbricoides, is the most common human worm infection. Worldwide, severe Ascaris infections cause approximately 60,000 deaths per year, mainly in children [2]. In the 1970s, Campbell and Omura discovered a class of compounds, called avermectins, that kill parasitic roundworms that cause infections such as river blindness (onchocerciasis) and lymphatic filariasis (elephantiasis). In Japan, Omura isolated strains of soil bacteria that were known to have antimicrobial properties. Omura’s institute signed a research partnership with Merch in 1973, and in 1974 his soil bacteria strains were sent to a team led by Campbell at the Merck Institute for Therapeutic Research in Rahway, New Jersey. Campbell’s team isolated avermectins from the bacterial cultures and developed the drug ivermectin. In 1987, Merck announced that it would donate ivermectin to anyone who needed it for treatment of river blindness. Ten years later, the company began giving away the drug to treat lymphatic filariasis. According to the Mectizan Donation Program, every year Merck gives away some 270 million treatments of the drug,

Malaria is a historic problem and one of the oldest human diseases, perhaps 50,000-100,000 years old. In the 1960s, the main treatments for malaria were becoming increasingly ineffective. In 1967, China established a national project against malaria to discover new therapies. Tu and her team screened more than 2,000 Chinese herbal remedies in search of drugs with antimalarial activity. An extract from the wormwood plant Artemisia annua proved especially effective and by 1972, the researchers had isolated chemically pure artemisinin. See the video below for more.

This year’s prize highlights the global acknowledgement on the importance of parasitic infections and neglected tropical diseases. Artemisinin has saved hundreds of thousands, if not millions of lives, and ivermectin has protected millions from disease.