The authors, lead by Omura, announced the discovery of Streptomyces avermilitis. They described the structure of avermectin, and reported preliminary observations that this drug is antiparasitic. (Order of authorship in the original publication: Burg, Miller, Baker....Omura.)

In 2015 the Nobel Prize in Physiology or Medicine 2015 was divided, one half jointly to William C. Campbell and Satoshi Ōmura "for their discoveries concerning a novel therapy against infections caused by roundworm parasites," and the other half to Tu Youyou "for her discoveries concerning a novel therapy against Malaria."

(Thanks to Juan Weiss for this reference and its interpretation.)

Digital facsimile from PubMedCentral at this link.