A significant drop in death rates occurred after a doctor implemented a new practice. Death rates fell from eighteen percent to one to two percent. This change was a result of physicians washing their hands frequently with a cleansing agent.

The discovery was made by a Hungarian doctor in the early 1840s. He found that doctors' hands were transferring harmful particles to patients.

Further information about this discovery and its impact is available from the original source, which describes the events and the doctor's findings in more detail.