Suppose that during ancient times, probably in either Greece, Rome, or China, but plausibly elsewhere, like in Babylon or Persia, someone, probably a doctor, recognizes a possible connection between poor hygiene and infectious diseases, so the technique of cleaning hands and medical instruments is tried and found to significantly reduce deaths by infection, and as a result, word spreads. In a matter of years performing medical procedures in hygienic conditions becomes standard. Let's also suppose that due to the fact of significant intercontinental trade links at this time (the Silk Road, ship routes), this knowledge spreads, and is eventually well-known by doctors throughout both Europe and Asia, perhaps even some civilizations in Africa that have contacts with Europe or Asia. What are the long-term effects of this?