Heroin "epidemics" have been reported in North America but not in Asia. Following passage of an anti-opium law in Laos, heroin use suddenly began in one area during 1972. Initially heroin use prevailed among indigenous Asian addicts, mostly older addicts who gradually switched from opium to heroin. In addition, there evolved a new group of indigenous addicts: young, single, unemployed males in urban areas whose first narcotic drug was heroin. After the appearance of heroin in Laos, increasing numbers of younger Americans and Europeans were soon attracted to heroin use in Laos.