How did the Romans cope with their diseases and were they even aware of their aetiology? The answer to this is the “De Re Rustica” of Terentius Varro. This may surprise us, but hundred years ago we were aware of the presence of microorganisms and their pathogenic effect on humans!
Especial care should be taken, in locating the steading, to place it at the foot of a wooded hill, where there are broad pastures, and so as to be exposed to the most healthful winds that blow in the region. A steading facing the east has the best situation, as it has the shade in summer and the sun in winter. If you are forced to build on the bank of a river, be careful not to let the steading face the river, as it will be extremely cold in winter, and unwholesome in summer. Precautions must also be taken in the neighbourhood of swamps, both for the reasons given, and because there are bred certain minute creatures which cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and there cause serious diseases.
We don’t know how Varro knew about it, since he adds that creatures were not visible. However, he probably had access to the achievements of science, which, however, lost itself in the darkness of history.
We also have no idea how it happened that knowledge and civilization fell so low that it took almost two thousand years for similar conclusions by Louis Pasteur and Joseph Lister or even later Alexander Fleming.
For example, the Egyptians 4.5 thousand years ago knew the effect of penicillin, although they probably called it differently. In several sources, we find information that lung diseases and wounds were treated with mouldy bread. Manuscripts found on papyri (Ebers Papyrus) to this day put scientists in astonishment, who agree that the knowledge contained there exceeded the knowledge of e.g. Hippocrates and Galen.