The nineteenth-century acceptance of germ theory transformed medicine and public health by revealing that invisible microorganisms shaped disease and could be controlled through systemic interventions. More than a century later, the Adverse Childhood Experiences (ACE) framework exposes another set of hidden determinants: childhood traumas that profoundly influence mental and physical health across the lifespan. Evidence consistently links ACEs to depression, substance use, chronic disease, and premature mortality, yet trauma-informed approaches remain marginal in many health systems.


This presentation will argue that the history of germ theory offers a powerful analogy for integrating ACEs into South African primary care. Like germs, trauma is invisible, stigmatised, and transmitted across generations; and like germs, it requires systemic rather than individual solutions. Using applied psychology as a lens, the presentation will explore barriers to integration, including limited visibility of trauma in clinical encounters, resource constraints, cultural pluralism, and policy gaps. Lessons drawn from germ theory highlight strategies that applied psychologists can advance: developing culturally adapted screening tools, training and empowering community health workers to deliver trauma-informed interventions, embedding evidence-based programmes into maternal and child health services, and advocating for alignment with National Health Insurance reforms.


By reframing ACEs as an unseen but actionable determinant of health, this presentation will demonstrate how applied psychology can contribute to systemic reforms that reduce intergenerational trauma and promote equity. For South Africa, and comparable contexts globally, integrating ACEs into primary care represents both a clinical necessity and a public health imperative.