Public health was the concept of maintaining the health of a population.
In, the Vidiian homeworld regulated group gatherings as part of their efforts to control the spread of the Phage, believing them to be a public health risk. While enjoying the atmosphere of Chez Sandríne on USS Voyager, Doctor Danara Pel was critical about their actions, remarking, "Sometimes I think my people spend so much time trying to save lives, they don't know how to live anymore." (VOY: "Lifesigns")
In 2377, Kadan proclaimed labor shortages to be the true public health threat, rather than the "outbreak" of Dysphoria Syndrome, and that locating skilled workers was the cure. (VOY: "Workforce")