Conditions For Successful Zoonosis
Zoonosis (transfer of a pathogen from non-human animals to humans) and subsequent spread of the pathogen between humans, requires the following conditions:
- a human population;
- a nearby population of a host animal;
- an infectious pathogen in the host animal that can spread from animal to human;
- interaction between the species to transmit enough of the pathogen to humans to establish a human foothold, which could have taken millions of individual exposures;
- ability of the pathogen to spread from human to human (perhaps acquired by mutation);
- some process allowing the pathogen to disperse widely, preventing the infection from "burning out" by either killing off its human hosts or provoking immunity in a local population of humans.
Read more about this topic: Origin Of AIDS, Emergence
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