* A lot of stuff in this movie is going to seriously {{Squick}} out [[TerrifiedOfGerms germophobes]] with the high BodyHorror quotient inherent in the premise. The best part? Necrotizing fasciitis is ''absolutely real''. Sweet dreams, kids.
** It's actually implied to be [=STD=]s or syphilis in the first film, which causes ulcerated sores to melt your face off just because you went bareback. However, it's less contagious.
* [[spoiler: Paul {{Mercy Kill}}ing Karen with a shovel, for one thing, Karen's face which has most of her flesh ''gone'' and the fact it's implied Paul suffered a SanitySlippage considering he saw Marcy ripped apart by the infected dog]].
** [[spoiler: The NightmareSequence Paul suffers when he dreams of Karen before the infection only to almost kiss her when she looked like the aforementioned scene. Complete with a chilling ScareChord]].
* The first movie shows [[spoiler: why you should never shave with a flesh eating virus. Graphically.]]
* Even the ''opening credits'' are unnerving, show what looks like a white sheet that becomes dirty over time before becoming bloodied, complete with an eerie tune with the ambiance of ''flies'' swarming nonstop.
* The infamous, FanDisservice scene in ''Patient Zero''. Two hot babes [[CatFight duking it out on the beach?]] Hot! Two hot babes [[spoiler: both of which are in the later stages of a flesh eating virus tearing each other apart on the beach, culminating in one caving the other's face in?]] Far, far from anything resembling hot.
** ''Patient Zero'' qualifies for the series' mandatory sex scene horrifically. [[spoiler: Namely, by showing exactly why you should open your eyes during oral.]]