5. explain how we know that ancient civilizations knew of and were concerned about infectious diseases.

We know from records left by these civilization and the research of historians who bring these records to the present day.

Explanation:

Diseases pose a terrible threat to every human being. Some are mild, but others may even kill millions - as has already happened - spreading to large parts of the world. For many centuries it was not known what produced the plagues and the great epidemics: a divine punishment? an astrological conjunction? a climate change? It took a long way to understand the cause of communicable diseases and how to prevent them.

All this way was recorded by doctors, healers and other health professionals of ancient civilizations, these records show us how people of this time treated and prevented infectious diseases. Although we now know that many of the techniques used by these people are inefficient today, but many of these records have been effective for today's medicine.