how come Alberto Rey did not get HIV from Bianca Biaggi,

split that booty 2 was released 6/1/2004
the only one movie that Bianca released after that was
Latina Fever 5 released on 9/13/2004

if the released dates correspond to production dates, then whoever had sex with her during latina fever should have gotten hiv unless HIV works in a strange way.... i do not understand this... anyone want to explain