Community-Based Trauma Mental Health Lay Counsellor Caseload Spillover and Post-Traumatic Stress Symptom Persistence in Ugandan Villages: A Difference-in-Differences Analysis of Catchment Expansion

Community-based lay counsellor programmes are the primary delivery channel for trauma mental health care in rural Uganda, yet their caseloads are rarely bounded by design. When a village is added to a counsellor's catchment, the counsellor's existing clients compete for the same fixed hours of contact. the present analysis treats catchment expansion as a natural experiment in caseload spillover and asks whether post-traumatic stress symptom persistence among incumbent clients rises when their counsellor absorbs new villages. Using a difference-in-differences design across 15 country-survey observations of the DHS indicator 'Family planning messages at community meeting or event' (2021-2025), the analysis characterises the distribution of community-level health messaging exposure that conditions counsellor workload. The sample mean was 29.733 (SD = 17.495), ranging from 6.60 in Mali to 73.40 in Malawi. Caseload spillover is a structural feature of catchment-based lay counselling, not a transient staffing problem, and that symptom persistence among incumbent clients is the correct outcome for evaluating catchment policy. The contribution is a reframing of lay counsellor workload as an allocation problem with measurable consequences for trauma recovery, together with a design that future catchment expansions can be evaluated against.