Practice of engaging in sexual activity, usually with individuals other than a spouse or friend, in exchange for immediate payment in money or other valuables. Prostitutes may be of either sex and may engage in either heterosexual or homosexual activity, but historically most prostitution has been by females with males as clients. Prostitution is a very old and universal phenomenon; also universal is condemnation of the prostitute but relative indifference toward the client. Prostitutes are often set apart in some way. In ancient Rome they were required to wear distinctive dress; under Hebrew law only foreign women could be prostitutes; in prewar Japan they were required to live in special sections of the city. In medieval Europe prostitution was licensed and regulated by law, but by the 16th century an epidemic of venereal disease and post-Reformation morality led to the closure of brothels. International cooperation to end the traffic in women for the purpose of prostitution began in 1899. In 1921 the League of Nations established the Committee on the Traffic in Women and Children, and in 1949 the UN General Assembly adopted a convention for the suppression of prostitution. In the U.S. prostitution was first curtailed by the Mann Act (1910), and by 1915 most states had banned brothels (Nevada being a notable exception). Prostitution is nevertheless tolerated in most U.S. and European cities. In The Netherlands many prostitutes have become members of a professional service union, and in Scandinavia government regulations emphasize hygienic aspects, requiring frequent medical examination and providing free mandatory hospitalization for anyone found to be infected with venereal disease. Prostitutes are very often poor and lack skills to support themselves; in many traditional societies there are few other available money-earning occupations for women without family support. In developing African and Asian countries, prostitution has been largely responsible for the spread of AIDS and the orphaning of hundreds of thousands of children.