Before Tom Frieden became director of the U.S. Centers for Disease Control and Prevention (CDC) in 2009, his two nemeses were tuberculosis and smoking. Although both are commonly described as threats to "public health," they differ in ways that may help explain the CDC's stumbles in dealing with Ebola. Tuberculosis, which Frieden helped control in New York City and India as a CDC epidemiologist, is a contagious, potentially lethal disease. Smoking, which Frieden targeted as New York City's health commissioner, is a pattern of behavior that increases the risk of disease.
As Jacob Sullum writes, that distinction matters to people who reject paternalism as a justification for government action. We believe the use of force can be justified to protect the public from TB carriers but not to protect smokers from their own choices.