Achieving equitable outcomes while innovating for neglected tropical diseases: evidence from community-based intervention studies in Malawi and Ghana

Background: Global strategy for neglected tropical diseases (NTDs) is intrinsically linked to the challenge of improving health equity: as conditions that disproportionately affect the most disadvantaged communities, interventions addressing NTDs are anticipated to reduce unfair differences that exist in health and access to health services. However, while substantial gains in the control and elimination of NTDs have been achieved over the past two decades,interventions addressing NTDs are rarely explored and evaluated from an equity perspective. Using two contemporary research areas for NTDs – elimination of soil-transmitted helminths (STH) and improved control of skin NTDs – this thesis aims to explore how and amongst whom gains have been achieved, and assess whether new strategies necessary to meet ambitious NTD goals can do so equitably. Methods: This thesis is nested within two intervention studies: DeWorm3 (2017-2022), a cluster-randomised trial of community-based mass drug administration (MDA) for elimination of STH in Malawi; and SHARP (2023-2024), a pre-post intervention study of an integrated approach for Buruli ulcer, leprosy, scabies and yaws in Ghana. In Malawi, I analyse data from community-based censuses, a cross-sectional parasitological survey, and longitudinal treatment registers to explore disparities in STH infection; and assess to what extent both routine and novel MDA strategies for STH can achieve equitable coverage amongst at those at greatest risk. In Ghana, I use routine health facility treatment records and a cross-sectional dermatological survey to explore demographic trends in changes in care seeking for skin diseases, and compare this to the profile of those at greatest risk of skin disease to assess the equity of such a strategy. Results: Despite sustained implementation of routine strategies for the control of STH in Malawi, a number of demographic groups, including out-of-school children and adult men, remain at greater odds of STH infection. Routine school-based MDA did not result in lower coverage amongst children with disabilities despite a strong association with lower school attendance, strengthening assertions for this platform as an equitable mechanism for delivery of basic health services. In contrast, adult men’s coverage remained substantially lower than women despite widening access through novel community-based MDA, demonstrating the potential for inequity where interventions fail to actively address the needs of those at greater risk. Strengthening the routine primary health system to diagnose and treat skin NTDs in Ghana resulted in substantial increases in care seeking across demographic groups, but those at greatest risk of disease remained disproportionately under-represented amongst those who sought care. Conclusion: These findings demonstrate the nuanced and variable extent to which interventions for NTDs – whether through expanded community-based approaches or strengthening existing routine health systems – are achieving equitable outcomes with respect to the determinants of health. I conclude by discussing the need to better address health equity in the design and evaluation of both routine and novel NTD interventions, and propose operational and research priorities to achieve this.