[Changes in prevention of infection: a historic retrospect].

The discovery of pathogenic microorganisms in the mid 19th century made possible an effective prophylaxis on a scientific basis. During many centuries, sequestration of leprous in specific dwellings was the custom; in the hindsight it proved to be instrumental for the almost complete disappearance of leprosy in Europe. This was also the case with the epidemics of plague, which, since the late Middle Ages, were stopped by measures of quarantine in ports and at frontier passages (e.g. Austrian plague-cordon). The beginning of internationally coordinated health measures was equally decisive. With smallpox, the variolation (since 1730) gave first relief, until Sir Edward Jenner discovered in 1798 the highly successful cross-immunity through vaccination. The development of sanitary conditions through better drinking-water supply, canalization and garbage disposal since the mid 19th century contributed much to the betterment of health, especially concerning cholera epidemics in cities. The reinforcement of the individual hygiene (body care, extermination of lice, antiseptic treatment of wounds, etc.) helped to achieve an adequate prevention and, together with intensified health education, a decline of infectious diseases in general.