If some diseases are contagious......?

If diseases like mumps, pink eye, chicken pox,
etc. are caught by interacting with someone who
is contagious, who did the first person to ever have
these diseases catch them from?

Excellent question,with a mighty convoluted answer. First,you're talking about diseases from totally different organisms,bacteria and viral. There are 2 types of diseases,ones that are infectous,"Extrinsic" meaning contagious,And non-infectious,general sort of disease",Intrinsic".There are hundreds of pathogens and viruses,and many ways to spread them,direct contact,airborne,saliva,blood,waterborne... insectsThe Bible speaks of epidemics and plagues,which were more likely infectious extrinsic diseases. Throughout history from the prehistoric times to the present our world has been aware of diseases with countless of millions of deaths recorded..The only problem back in the most earliest of times was the lack of understanding of what was happening,and the understanding of sanitation and sources of contamination etc.This understanding and development of medicines and isolation of the bacteria responsible, was finally discovered in France, in the 1800's by Louis Pasteur,and in Germany by Robert Koch's "germ theory".There have been exposure to bacteria since the dawning of time,there's no way to know,exactly which one,and under what circumstances.Viruses and bacteria both are opportunistic,as they still are today. Like the plagues of the dark ages,take fleas,and rats,filth and human hosts to bite,there you have the beginnings of a new" black death". Only in these times, world wide spread is possible in 24 hours because of "jet" air travel,not years as it was in those times,by slow moving sailing ships.Bacteria form on spoiled food,or poorly cooked meat,you come by,and eat the food,and then you are infected and come down with food poisoning. The same thing probably happened in the Garden of Eden. Take care. SW RNP