Post-trial malaria surveillance following community-wide mass drug administration and delayed implementation in Ghana: a repeated cross-sectional study

Background Community-wide mass drug administration (MDA) can reduce malaria transmission by clearing symptomatic and asymptomatic infections and reducing the parasite reservoir. However, evidence on persistence of these reductions after intensive MDA and malaria trends following delayed implementation in untreated communities remains limited. We assessed malaria prevalence and childhood anaemia during post-MDA surveillance following a cluster-randomised MDA trial in Ghana. Methods Repeated cross-sectional surveillance was conducted in 18 communities (nine intervention and nine former control communities) in November 2024, March 2025, and July 2025. The November 2024 parent-trial endline also served as the post-MDA surveillance baseline, before post-trial MDA. Subsequent MDA was implemented four months apart in both arms, with booster MDA in intervention communities and delayed MDA in former control communities. Approximately 100 randomly selected participants per community were assessed at each survey using HRP2-based rapid diagnostic tests; haemoglobin was measured among children aged ≤ 15 years. Results At the November 2024 post-MDA baseline, malaria prevalence was 1.5% (15/974) in intervention communities versus 26.2% (236/902) in former control communities. Prevalence remained low in intervention communities (1.8% and 0.9% in March and July 2025, respectively) and declined in former control communities (9.0% and 0.7%). By July 2025, prevalence had converged to low levels. Among children aged ≤ 15 years, anaemia prevalence was 8.9% in intervention communities and 54.5% in former control communities at baseline, declining to 8.9% and 9.0%, respectively, by July 2025. Conclusions Very low RDT-detectable malaria prevalence was maintained in intervention communities, while prevalence in former control communities declined during delayed implementation and became similarly low by July 2025. Together with the marked reduction in childhood anaemia, these findings indicate favourable health gains following the broader MDA intervention package and highlight the value of continued community-based surveillance as malaria prevalence approaches very low levels. This context provides an opportunity to layer complementary elimination interventions, including malaria vaccination and transmission-reducing approaches such as gametocytocidal therapy, alongside surveillance and targeted responses to residual infection. Although the non-randomised post-trial design limits causal attribution of subsequent changes specifically to delayed or booster MDA, the findings can inform integrated strategies to sustain and advance malaria elimination.