JMIR Publications

ABSTRACT

Background:

Plasmodium vivax (P. vivax) has emerged as the primary cause of malaria in Cambodia. Achieving malaria elimination and securing malaria-free certification requires a focused effort on addressing P. vivax malaria. This is essential because the elimination of P. vivax often lags behind that of Plasmodium falciparum, making it a critical component in the overall strategy.

Objective:

This study will assess the feasibility of the Mass Drug Administration (MDA) and P. vivax Serological Testing and Treatment (PvSeroTAT) integrated with Reactive Case Detection (RACD) in two of the highest malaria burden operational districts of Cambodia and examine the potential for integrating these two approaches with existing malaria elimination efforts.

Methods:

This study employs an observational, prospective cohort design. MDA with chloroquine (CQ) will be conducted in Stung Treng through four monthly rounds, while RACD with PvSeroTAT will be implemented in Sen Monorom, targeting households near confirmed P. vivax cases. Data on coverage, compliance, cost, and stakeholder perceptions will be collected through surveys, interviews, and malaria case monitoring. A Composite Feasibility Index will integrate quantitative and qualitative indicators. Cost and budget impact analyses will assess scalability for malaria-endemic districts.

Results:

This study was funded by Medicines for Malaria Venture and approved by the National Ethics Committee for Health Research (NECHR) in Cambodia on 26 February 2025 (No. 085 NECHR). The study implementation began in March 2025. Training of study staff and healthcare workers was conducted between March – May 2025. Participant enrolment for MDA and RACD began in April and ended in October 2025. Altogether, 4443 and 3371 participants were recruited in MDA and RACD, respectively. Data analysis will be completed after the end of regular follow-ups by April 2026.

Conclusions:

Innovative and targeted public health approaches and tools are necessary to ensure the elimination of the malaria parasite reservoir, including the hidden hypnozoites. While MDA with CQ clears active blood-stage infections leading to immediate reductions in malaria prevalence, PvSeroTAT can detect past exposure to P. vivax by using serological markers allowing for targeted treatment of individuals at risk of developing relapsing infections with an 8-aminoquinoline. This helps reduce the parasite reservoir more efficiently. This study will provide insight into operational feasibility, implementation costs, community acceptance, and long-term sustainability. The findings will guide Cambodia’s malaria elimination efforts through improved surveillance and targeted interventions. Clinical Trial: OSF Preregistration: https://doi.org/10.17605/OSF.IO/5KZH7, retrospectively registered 15 October 2025.