A Brief History of Malaria

Fig.1. Tu Youyou (right) and tutor Lou Zhicen in 1950s (Credit: Xinhua News Agency) 

In 1967, Mao Zedong held a meeting in Beijing to discuss the major problem of drug-resistant malaria affecting soldiers on the front lines of the Vietnam War. Efforts in the United States resulted in the discovery of the drug mefloquine, but the North Vietnamese turned to China for aid. A program was formed that involved more than 500 scientists from around China to develop effective antimalarial medication. Among those scientists was Tu Youyou, a pharmacologist who is now a 2015 Nobel Prize recipient in Physiology or Medicine for her work in drug development.

Malaria is a mosquito-borne disease caused by protozoan parasites in the genus Plasmodium. Nearly 3.4 billion people live in areas at risk of malaria transmission, and in 2013, 198 million cases occurred worldwide. The 1960s saw the rise of chloroquine-resistant Plasmodium falciparum, which causes the most deadly form of malaria. When Tu began her work, more than 240,000 compounds around the world had already been tested for antimalarial properties to no avail.

She gathered a team to try a new method of drug discovery. Together, they screened more than 2,000 Chinese herbal remedies and combed through ancient Chinese manuscripts to find historical cures for the disease. A record from around 300 A.D. led Tu and her colleagues to the herb known as sweet wormwood (Artemisia annua).

Initial extractions were inconsistent in inhibition rates of the parasite until Tu returned to the literature. The manuscript called for cooking the herb at low temperatures instead of the traditional methods of boiling to extract compounds. In 1972, these tests resulted in a chemically pure form of the drug artemisinin, which remains today as the first-line treatment for uncomplicated Plasmodium falciparum malaria.

The records Tu analyzed are not the only mentions of malaria in history. References stretch back to Chinese documents from around 2700 B.C., Mesopotamian clay tablets from 2000 B.C., Hindu texts from the sixth century B.C., and more. These historical texts hold a wealth of information and continue to inform scientists about medicine, climate, and even conservation. Additionally, they also emphasize the need for associated data with collections. Records, notes, and histories of samples are essential to understanding how collections fit into the natural world and connect to human society. As seen with Tu’s research, historical texts can inform groundbreaking work and show the development of medicine over time.

The international spotlight on her work serves to highlight the need to return to records in collections, as well as ongoing work against diseases that are a huge economic burden on impoverished nations. Tu shares her prize with microbiologists William Campbell and Satoshi Ōmura, who discovered a class of compounds that kills parasitic roundworm, the pathogen of river blindness. Although these parasites continue to strain healthcare systems around the world, the researchers' creative work in drug discovery gives hope in the fight against disease.


References:
Callaway, E., & Cyranoski, D. (2015, October 5). Anti-parasite drugs sweep Nobel prize in medicine 2015. Nature. Retrieved from http://www.nature.com/news/anti-parasite-drugs-sweep-nobel-prize-in-medicine-2015-1.18507

Cox, F. E. G. (2010). History of the discovery of the malaria parasites and their vectors. Parasite Vectors, vol. 3 (5). doi: 10.1186/1756-3305-3-5

Hatton, C. (2015, October 6). Nobel Prize winner Tu Youyou helped by ancient Chinese remedy. BBC News. Retrieved from http://www.bbc.com/news/blogs-china-blog-34451386

Malaria: Q&A on artemisinin resistance. (2015, February). World Health Organization. Retrieved from http://who.int/malaria/media/artemisinin_resistance_qa/en/

Miller, L. H., & Su, X. (2011, September 16). Artemisinin: Discovery from the Chinese Herbal Garden. Cell, vol. 146 (6): 855-858. doi: 10.1016/j.cell.2011.08024

Glossary

protozoan parasites
A type of parasites which are made up of single-celled eukaryotic organisms known as protozoa. Diseases caused by protozoan parasites include Malaria, Chagas Disease, Sleeping Sickness, and Giardiasis.