Modern day challenges to public health systems include—as well as infectious and chronic diseases—the need to improve environmental health, occupational health, and mental health; to reduce injuries; to strengthen systems for delivering public health services; and to prepare for unanticipated problems and emergencies, such as natural disasters and bioterrorism.

Public health services have developed in a less consistent manner than medical services in hospitals, clinics, and primary care. But, from 19th century pioneers of public health such as Farr, Chadwick, and Snow in England; Shattuck in the United States; and Frank, Villerme, and Virchow on the European continent,1 to Yen and Grant in Ding County, China,2 disciplines and skills have evolved into a set of recognised essential public health capacities. As defined by the Pan American Health Organization3 and the US Centers for Disease Control and Prevention (CDC),4 such capacities permit a nation—through its public health authorities—to recognise, measure, and tackle health challenges through population based interventions.3

Many countries find it useful to group target problems …