Factors associated with leprosy transmission, West Nile region, Uganda, January 2024–April 2025: A case-control study

Introduction: In April 2024, Koboko and Nebbi Districts in the West Nile Region of Uganda reported 48 newly diagnosed leprosy cases within a short period, representing a fivefold increase compared to the annual average of fewer than 8 cases reported in 2020. This unexpected rise in new case notifications raised concerns about ongoing transmission in the region. We assessed factors associated with leprosy transmission in these districts to inform targeted interventions. Methods: We conducted an unmatched case-control study involving 73 cases and 202 controls in Koboko and Nebbi Districts. Cases were persons with a documented leprosy diagnosis based on clinical assessment and health-facility records, with slit-skin smear examination for acid-fast bacilli performed where clinically indicated. Controls were persons without any signs or history of leprosy (no hypopigmented or reddish skin lesions with definite sensory loss or thickened peripheral nerves) residing in the same neighborhoods as the cases. All identified cases from the medical records were enrolled, and approximately three neighborhood controls were selected per case. We collected data on sociodemographic characteristics, clinical history, household contacts, and care-seeking behavior using interviewer-administered questionnaires. Risk factors for leprosy transmission were identified using multivariable logistic regression. Results: We enrolled 275 participants, including 73 cases and 202 controls. Among the cases, 67/73 (92%) were aged ≥15 years, 47/73 (64%) were female, 48/73 (66%) were peasant farmers, 45/73 (62%) lived below the poverty line, and 37/73 (51%) had multibacillary disease. In multivariable analysis, close contact with a leprosy patient (aOR=3.83, 95% CI: 2.07–7.09) and living below the poverty line (aOR=3.57, 95% CI: 1.84–7.14) were independently associated with leprosy. Conclusion: The investigation identified socioeconomic vulnerability and close contact with a confirmed leprosy patient as factors independently associated with leprosy in the Nebbi and Koboko districts. Enhancing active case finding, contact tracing, and community awareness, especially among high-risk groups, is crucial to accelerate progress toward leprosy elimination in Uganda.