Accelerating towards <i>P. vivax</i> elimination with a novel serological test-and-treat strategy: a modelling case study in Brazil.

Abstract

<i>Plasmodium vivax</i> malaria is challenging to control and eliminate. Treatment with radical cure drugs fails to target the hidden asymptomatic and hypnozoite reservoirs in populations. <i>Pv</i>SeroTAT, a novel serological test-and-treat intervention using a serological diagnostic to screen hypnozoite carriers for radical cure eligibility and treatment, could accelerate <i>P. vivax</i> elimination. Using a previously developed mathematical model of <i>P. vivax</i> transmission adapted to the Brazilian context as a case study for implementation, we evaluate the public health impact of various deployment strategies of <i>Pv</i>SeroTAT as a mass campaign. We compare relative reductions in prevalence, cases averted, glucose-6-phosphate dehydrogenase (G6PD) tests, and treatment doses of <i>Pv</i>SeroTAT campaigns to strengthened case management alone or mass drug administration (MDA) campaigns across different settings. Deploying a single round of <i>Pv</i>SeroTAT with 80% coverage to treat cases with a high efficacy radical cure regimen with primaquine is predicted to reduce point population prevalence by 22.5% [95% UI: 20.2%-24.8%] in a peri-urban setting with high transmission and by 25.2% [95% UI: 9.6%-42.2%] in an occupational setting with moderate transmission. In the latter example, while a single <i>Pv</i>SeroTAT achieves 9.2% less impact on prevalence and averts 300 less cases per 100,000 than a single MDA (25.2% [95% UI: 9.6%-42.2%] point prevalence reduction versus 34.4% [95% UI: 24.9%-44%]), <i>P</i>vSeroTAT requires 4.6 times less radical cure treatments and G6PD tests. Layering strengthened case management and deploying four rounds of <i>Pv</i>SeroTAT six months apart is predicted to reduce point prevalence by a mean of 74.1% [95% UI: 61.3%-86.3%] or more in low transmission settings with less than 10 cases per 1000 population. Modelling predicts that mass campaigns with <i>Pv</i>SeroTAT are predicted to reduce <i>P. vivax</i> parasite prevalence across a range of transmission settings and require fewer resources than MDA. In combination with strengthened case management, mass campaigns of serological test-and-treat interventions can accelerate towards <i>P. vivax</i> elimination. This project was funded in part by the Bill and Melinda Gates Foundation and the National Health and Medical Research Council.