“Ebola’s only mission is to never stop replicating, and to never stop moving from person to person... and thereby to make itself immortal in the human species.”
In this passage, Preston personifies the Ebola virus in order to emphasize the fact it seemingly has its own motivations and aims. This gives the virus a disturbingly human quality, making it seem more powerful and malicious. Essentially, the aim of any disease is to spread as much as possible, which Preston describes here.
“Ebola virus moves from one person to the next by following the deepest and most personal ties of love, care, and duty that join people to one another and most clearly define us as human. The virus exploits the best parts of human nature as a means of travel from one person to the next. In this sense, the virus is a true monster.”
Here, Preston is writing about how the virus spreads. Essentially, the virus spreads from human contact, such as hugging and talking. This makes it an especially cruel affliction as it takes advantage of the things that create a sense of connection or as Preston words it "the best parts of human nature."
“Viruses more powerful and dangerous than Ebola were going to emerge in the future, and medical people were going to have to deal with them."
Preston writes here about the possibility of more epidemics in the future. He argues that we have a responsibility to help those in the future by preparing in advance for such eventualities and doing our best to lower the risk of it happening.
