2015 Nobel Prize in Physiology or Medicine(1)
Reason for Award
for their discoveries concerning a novel therapy against infections caused by roundworm parasites
Laureates
Ireland, 
United States of America
Japan
Explanation
Tiny worms called roundworms live in rivers and soil and can get into people and animals, causing disease. Although almost invisible, they can multiply inside the body and lead to itching or even blindness. Mr. Campbell and Dr. Ōmura found that a substance made by soil bacteria can kill these worms. They turned this substance into a medicine called ivermectin; taking it once or twice a year removes most worms. Thanks to this drug, millions of people are now protected from blindness and swollen limbs.
Related Keywords
roundworm
Roundworms are nematode parasites that invade humans and livestock and feed on host nutrients. Species such as Onchocerca volvulus and Wuchereria bancrofti cause river blindness and elephantiasis. Transmission typically involves insect vectors, and adult worms may live for years within the host. Because nematodes do not self-replicate in humans, repeated exposure worsens disease severity. They remain a focal point of parasitology and public-health research.
avermectin
Avermectins are a family of macrolide natural products produced by Streptomyces avermitilis. Eight congeners exist, with B1a being the prototype. They activate glutamate-gated chloride channels in nematodes, causing paralysis. First commercialized in the 1970s for veterinary use, they laid the chemical foundation for ivermectin.
ivermectin
Ivermectin, 22,23-dihydroavermectin B1, is a broad-spectrum anthelmintic. A single oral dose rapidly clears blood microfilariae. Through WHO-industry donation programs, more than 200 million people receive it annually. Its indications now include scabies and head-lice infestations. Possible antiviral properties are under investigation.
river blindness
River blindness, or onchocerciasis, results from infection with Onchocerca volvulus transmitted by blackflies. Microfilariae migrate to the eyes and induce corneal opacity leading to blindness. It is endemic in central Africa and hampers economic productivity. Annual ivermectin administration blocks transmission, and elimination campaigns are underway. Education and vector control complement drug treatment.
lymphatic filariasis
Lymphatic filariasis occurs when filarial worms invade lymphatic vessels, causing chronic inflammation and massive swelling of limbs or scrotum. Mosquitoes transmit the parasite, and over 120 million people suffer from sequelae such as elephantiasis. Combined ivermectin and albendazole therapy is the treatment of choice. Social stigma and reduced employability are major concerns. Global elimination is targeted for the early 2020s.
Streptomyces avermitilis
A soil actinomycete that produces avermectins via a sophisticated polyketide synthase system. Isolated by Satoshi Ōmura from Japanese soil. Its ~9 Mb genome has been sequenced, and engineered strains enhance industrial yields. The organism exemplifies the drug-discovery potential of microbial diversity and serves as a model in synthetic-biology studies.