Abstract
Long before COVID-19 made social distancing familiar, people with cystic fibrosis (CF) already practiced such behaviors. CF is held up as a classic example of genetic disease, yet people with CF are also susceptible to bacteria from the environment and from other CF patients. Starting in the 1980s, a bacterial epidemic in the CF population highlighted clashing priorities of connection, physical safety, and environmental protection. Policymakers ultimately called for the physical separation of people with CF from one another via recommendations that reconfigured the CF community. Simultaneously, medical researchers recognized that one highly transmissible CF pathogen called cepacia was being developed for environmental applications and got the EPA to limit cepacia's environmental deployment. Environmental regulations speak to the challenge of useful microbes that harm a minority, but CF cross-infection also involves legal implications for microbial and genetic discrimination, social consequences for CF communities, and ethical questions about balancing autonomy, harms, and benefits. As scientists increasingly study connections between host genetics, microbial genetics, and infectious risks, CF is a vital referent.