Preston uses personification.

"Then his stomach screwed up into a knot and turned over, and he felt an unpleasant sensation." (Page 314)

Preston employs the literary technique of personification as a way to immediately establish the virus’s role in the book. He writes, “Having destroyed its host, the hot agent is now coming out of every orifice, and is ‘trying’ to find a new host.”

"Nature seemed to be closing in on us for a kill, when she suddenly turned her face away and smiled. It was a Mona Lisa smile, the meaning of which no one could figure out. " (pg, 355)