A wide range of sociological studies on the social crontrol of sickness have focused on medicalization or on the process through which social phenomena are regulated by medicine. On the contrary, little attention has been devoted to how social problems historically understood as medical come to be governed by the criminal law, or what is here termed the "criminalization of sickness." Criminal statuses that require all HIV-positive individuals to disclose their infection before engaging in a wide range of sexual practices have been enacted in thirty three US states. Drawing on evidence from 58 felony nondisclosure convictions in Michigan (95% of all convictions between 1992 and 2010), we argue that the enforcement of the state's HIV disclosure law is not driven by medical concerns or public health considerations. By contrast, it reflects a pervasive moralizing attitude that frame HIV as a moral infection requiring interdiction and punishment.