Control of VES is counted as a notable success story for regulatory veterinary medicine in the United States; within 24 years of its discovery as an entirely new disease, it was said to have been eradicated. However, its origins were not known but were said to have been [de novo] or from some unknown wild animal reservoir, which was extensively sought but not found. Swine were the only naturally infected host species; no evidence of human infection had been observed. It was only in 1972 that the same virus that caused classic VES was isolated from a population of San Miguel sea lions.