The Spread of Disease In the New World

The Spread of Disease In the New World

The extraordinary good health of the natives prior to the coming of the Europeans would become a key ingredient in their disastrous undoing. The greatest cause of disease in America was epidemic diseases imported from Europe. Epidemic diseases killed with added virulence in the " virgin soil" populations of the Americas. The great plague that arose in the Old World never emerged on their own among the western hemisphere and did not spread across oceans until Columbus' discovery.

Disease and parasitism play a pervasive role in all life. Many of these diseases start with microparasites, which are characterized by their ability to reproduce directly within an individual host. They are also characterized by their small size, short duration of infection, and the production of an immune response in infected and recovered individuals. Microparasites which damage hosts in the course of their association are recognized as pathogens. The level of the interaction and the extent of the resultant damage depends on both the virulence of the pathogen, as well as the host defenses. If the pathogen can overcome the host defenses, the host will be damaged and may not survive. If on the other hand the host defenses overcome the pathogen, the microparasite may fail to establish itself within the host and die.

The main objectives of the pathogen are to gain entry inside the host, once inside grow and reproduce, and avoid host defenses. There are three possible routes of infection: respiratory, alimentary, and traumatic. The respiratory route is the easiest and most direct means of entry. Under crowded conditions, the rate of infection is even more rapid. The diseases brought over to America were mainly spread by the respiratory method. The alimentary pathway of infection is through the ingestion of contaminated food and water. Throughout Europe during the 15th century, food and water were contaminated with fecal matter and by unsanitary habits ( i.e. the lack of bathing). The traumatic route of infection is through insect and animal bites.

The objective of the host is to "escape" from the pathogen. This can be done through the use of the immune system or by quickly dying. When a host dies with the pathogen still inside the pathogen dies as well. Resistance to invaders evolved as a result of the development of the mechanism of immunity. The development of immunity depends on the recognition of differences in chemical structures of substances.