The term emerging diseases includes infectious diseases that have recently been described or developed or diseases which, while were already known, recently increased their incidence or their expansion into new geographic areas or infect new hosts or employ new carriers.The concept of "emerging diseases" developed by scientists who were trying to document and explain the sudden increase in the number of new and important diseases during the past two decades.
The procedures and factors that led to the rise of emerging diseases are: 1) changes concerning the pathogens themselves or their range of hosts (breaking the barrier of the kind),2) changes of the ecosystem due to natural or anthropogenic causesalong with climatic and geographical influences to pathogens and their carriers,3) intense movements of the human population and their increased contact with animals or their products, 4) increased movement of animals and animal products, 5) the improvement of diagnostic and epidemiological techniques resulting in the detection of existing or emerging pathogens.
