Later than Usual this week (sorry) some may not count as straight forward "infection" but hey!
As always in no specific order
The Children (1980) (it's one of my all time fav "bad" movies just search the forum LOL) and Frankie got away with it so
Demons (1985)
28 Weeks Later
Rabid
I Drink your Blood
The Crazies (2010)
The Curse (1987)
Masque of The Red Death
Warning Sign (1985)
Shivers