Public health incorporates the interdisciplinary approaches of epidemiology, pharmacoepidemiology, biostatistics, environmental health, community health, behavioral health, health economics, public policy, insurance medicine, occupational safety and health, and other health services. The focus of a public health intervention is to prevent and manage diseases, injuries and other health conditions through surveillance of cases and the promotion of healthy behaviors, communities and environments. The three core public health functions are: ƒ The assessment and monitoring of the health of communities and populations at risk to identify health problems and priorities ; ƒ The formulation of public policies designed to solve identified local and national health problems and priorities ; ƒ To assure that all populations have access to appropriate and cost-effective care, including health promotion and disease prevention services, and evaluation of the effectiveness of that care. Mental health is integral to overall health and wellbeing and should be treated with the same urgency as physical health. Mental illness can influence the onset, progression, and outcome of other illnesses and often correlates with health risk behaviors such as substance abuse, tobacco use, and physical inactivity. Depression has emerged as a risk factor for such chronic illnesses as hypertension, cardiovascular disease and diabetes, and can adversely affect the course and management of these conditions.