Prostitution, during the Late Middle Ages prostitutes lived in special houses (documented mention of a "house of women" in Vienna, 1382). As syphilis spread in Austria after the discovery of America, and concepts of morality became more stringently defined by the Reformation and Counter-Reformation, the social status of prostitution decreased. Maria Theresia sought to eradicate prostitution, but failed in the long run. Prostitution was controlled by police surveillance and being confined to brothels (1873: "health books" for registered prostitutes), but secret prostitution remained a problem, especially in Vienna. Here prostitution was concentrated in certain districts (Spittelberg, today Vienna´s 7th district) in the 18th and in the early 19th centuries. Around 1820 the number of prostitutes in Vienna reached an estimated 20,000 and around 1890 about 25,000; 1,879 prostitutes were officially registered in 1913, 711 in 1993.