Active follow-up of Plasmodium vivax radical treatment in a mobile and hard-to-reach population in the Amazon: results from the CUREMA project.

BackgroundEvidence from real-world implementation of follow-up and pharmacovigilance for Plasmodium vivax treatment in population scale interventions targeting asymptomatic individuals remains limited, especially among highly mobile, hard-to-reach groups. This study describes the follow-up strategy used in the CUREMA project and assesses its implementation, as well as safety, tolerability, and adherence outcomes. MethodsThe CUREMA project implemented a PvTDA (P. vivax targeted drug administration) intervention in cross-border Amazonian settings, consisting in a full course treatment with chloroquine and primaquine (7 days) or tafenoquine (single dose), after screening its main contraindications (including semiquantitative G6PD testing); its target population was represented by artisanal and small scale migrant miners evaluated as at risk for asymptomatic P. vivax carriage. Treatment follow-up was mandatory for PvTDA participants and combined in-person visits or telephone interviews, and/or a tailored smartphone application, to be compatible with target population high mobility. Planned follow-up visits were scheduled 2, 5, and 14 days after treatment initiation. Univariate analyses described app uptake, follow-up completion, adverse events and treatment declared adherence; multivariable regression models explored factors associated with these outcomes. ResultsAmong 294 participants who received PvTDA, 269 (91.5%) configured the smartphone application, 100 (34.0%) selected telephone follow-up and/or 44 (15.0%) selected in-person follow-up. Overall, 210/294 participants (71.4%) completed at least one follow-up questionnaire, and 81/294 (27.6%) completed the three follow-up visits At least one adverse event was recorded in 49/294 participants (16.7%); events were generally mild to moderate, and no serious adverse event was identified. The declared adherence to the 7-days chloroquine and primaquine treatment was 79.2% [95% CI 72.5-86.4]. ConclusionsActive follow-up of P. vivax radical treatment was feasible in a highly mobile, remote population when multiple complementary tools were combined. This supports pharmacovigilance and safe implementation of radical cure strategies in similarly challenging settings.