Answer:
The author's discussion of the shared virus between the pigs and the bats shows us that animals play a huge role in human diseases by acting as a sort of middleman between the virus and humans. They harbor the virus which they then pass to humans through contact or when the humans end up eating the infected animal.
Step-by-step explanation:
Animals serve as hosts to various pathogens which cause human diseases, if a human is infected with a virus they are not immune to, the pathogen then has found a way to infect several more people through that infected human.
The bats are the carriers of the virus with which they infect the pigs through their droppings and saliva, the pigs then pass the virus to humans by contact alone, which results in the widespread of the virus as the virus have not had a human host before, so the humans are not immune to it.