John Snow did pioneering work on the causes of cholera. This fascinating website includes the full text of Snow's 1855 publication On the Mode of Communication of Cholera and maps illustrating his work and ideas. See also Cholera Inquiry Commission Report 1854 "into the causes which have led to, or have aggravated, the late outbreak of Cholera in the towns of Newcastle-upon-Tyne, Gateshead and Tynemouth."
Antiquus Morbus - A Glossary of Archaic Medical Terms, Diseases and Causes of Death
Records of Dentists, Doctors and Nurses - see Occupations
Hospital Records Database (A Joint Project of the Wellcome Trust and the Public Record Office) "This database provides information on the existence and location of the records of the hospitals in the U.K.".
Historic Hospitals - An Architectural Gazetteer, by Harriet Richardson. Provides brief histories, and numerous pictures and maps, of a large number of hospitals in Scotland, and of mental hospitals in Britain and Ireland.