Question

Does a pathogen cause disease in a reservoir host?

Answer 1

Although pathogens do have the capability to cause disease, they do not always do so. This is described as context-dependent pathogenicity. Scientists believe that this variability comes from both genetic and environmental factors within the host. One example of this in humans is E. coli. Normally, this bacteria flourishes as a part of the normal, healthy microbiota in the intestines. However, if it relocates to a different region of the digestive tract or the body, it can cause intense diarrhea. So while E. coli is classified as a pathogen, it does not always act as such. This example can also be applied to S. aureus and other common microbial flora in humans.