The majority of<unk>  infections are acquired through unprotected sexual intercourse. The exposures with the highest risk of contracting disease include contaminated blood transfusions, childbirth, needle sharing, and receptive anal intercourse.  Needle sharing is the cause of one third of all new<unk> -infections. Infectivity varies along the course of the disease and is closely associated with the<unk>  viral load.
HIV AIDS risk factors
Smallpox risk factors
Cytomegalovirus infection risk factors
Neurosyphilis risk factors
Leprosy risk factors
Ebola risk factors
Syphilis risk factors
Chickenpox risk factors