JMIR Publications

ABSTRACT

Background:

A challenge in achieving the malaria-elimination target in the Greater Mekong Subregion, including Thailand, is the predominance of Plasmodium vivax malaria, which has shown extreme resilience to control measures.

Objective:

This study aimed to provide the evidence base for implementing primaquine mass drug administration (pMDA) as a strategy for P. vivax elimination in low endemicity settings.

Methods:

The study employed a mixed-methods trial to thoroughly evaluate the effectiveness, safety, and acceptability of pMDA. The implementation study was designed as a cross-over cluster-randomized control trial with pMDA supplementing standard malaria-prevention and -control practice. A qualitative study employed in-depth interviews and focus-group discussions. Five cross-sectional blood surveys (CSSs) were conducted for both pMDA and control groups before, and 3-months after, pMDA. The effectiveness of pMDA was determined by comparing P. vivax incidences between the two groups with a multilevel zero-inflated negative-binomial model. At each time-point of the CSS, the incidence was also compared descriptively to the reported malaria prevalence captured by the national malaria surveillance system. The safety data comprised adverse events occurring after drug administration. Content analysis was used to assess acceptability.

Results:

A total of 2550 individuals in seven clusters were enrolled into the study. P. vivax infection drastically decreased in all study clusters. The incidences of the two groups at all five CSS times were not statistically significantly different. The incidences at the CSSs were higher than those reported by the national malaria surveillance system. There were no major safety concerns. Acceptance among the study participants and public healthcare providers at local and national levels was high, and they believed that pMDA had boosted awareness in the community.

Conclusions:

pMDA showed high adherence, safety and tolerability, but may not significantly impact P. vivax transmission. The study revealed that active CSS detected asymptomatic cases in the communities that were not detected by the passive malaria surveillance system. The study has showed that pMDA is an effective strategy at point-of-care and community levels with collaboration and commitment from local and national authorities. These efforts boosted the acceptability of the malaria-elimination initiative. In striving to achieve elimination targets, similar efforts are recommended. Clinical Trial: Thai Clinical Trials Registry. TCTR ID : TCTR20190806004 : (https://www.thaiclinicaltrials.org/show/TCTR20190806004)