Abstract:  Humans face constant threats from their environment. One of them is from the parasites that live and propagate inside our body, which may cause diseases and death. Majority of the world population are facing with challenges from various parasitic infections and millions of people died from infectious diseases every year. Two anti-parasitic disease drugs discovered 40 years ago, the anti-River Blindness and Lymphatic Filariasis drug Avermectin discovered by William C. Campbell and Satoshi ōmura, and the anti-Malaria drug discovered by Youyou Tu, revolutionized the treatment for the diseases and changed the lives of millions who are af?icted by the diseases. Because of the great contributions they made in solving the major global health problems, the 2015 Nobel Prize in Physiology or Medicine was awarded to the three scientists.