Prior to this period in history china experienced an economic revolution and expanded its influence on the surrounding areas. It was then that it was invaded by the Islamic tribes like Mongols who were nomadic. Bearing that pathogenia was spread by fleas that infested both animals and humans it can be doubtlessly proven that from this nomadic tribe fleas emanated and spread the disease hence by the 9th century it is possible that Y-pathogenia was present in China. Likewise X-actogenia evolved by the same mechanism.
Similarly in the 14th century Europe also underwent economic and social changes. Many people migrated to the cities where they had improved living standards. The economic changes facilitated the growth of commerce that led to the opening up of national and international trades. With the growth of trade, in the 16th century the rulers in Europe adopted mercantilism which was an economic system that helped improve to national wealth. With this Europe succeeded in expanding its colonies and there increased a sort of interaction. This can be viewed as the origin of Y-pathogenia in Europe. It was also the source point in history where X-actogenia can be traced.
The narrative of the history of medicine
This is about how diseases became dominant with the rapid changing and evolution of medicines. Once treated with a certain kind of medicine the disease would change to another form that required a different attention from which was there at the beginning
Basing on the diseases we have so far discussed the three diseases that had the greater impact in history are:
1. Black Death. This disease was trans-continental and killed many Europeans in the 14th century records show that in its first emergence about a third of the European population was ravaged. The historians regarded this period as watershed event. It is caused by the bacterium Yesnia pestis. The bacterium was spread by infected fleas that lived on the black rats. 60 to 80 percent of the infected people died three to five days after the incubation period that lasted for three to five days also.
2. Next on line was the smallpox. Its first appearance in the new world had very devastating effects and especially to the Central America. It is caused by Variola major. The disease is transmitted by inhalation and also from the sores of the infected. The survivors of this disease are usually pork marked but are completely immune to future attacks.
3. Third is cholera. The earliest reference dated to 14th century. The 19th century witnessed a series of serious pandemics. The first swept the eastern hemisphere followed by another one that reached Europe. It continued to Ireland from where the immigrants transported it to North America. It later invaded England where it caused the most and the greatest number of deaths.
The causative agent for this disease is Vibrio cholerae. Its commonly known path of infection is contaminated sewage that comes into contact with water used for domestic purposes e.g. drinking. All the three diseases belong to the fellow traveler school of thought.
