Declining Burden of Plasmodium vivax in a Population in Northwestern Thailand from 1995 to 2016 before Comprehensive Primaquine Prescription for Radical Cure.

Cindy S Chu,Verena I Carrara,Daniel M Parker,Rose Mcgready,Prakaykaew Charunwatthana,Stéphane Proux,François Nosten

doi:10.4269/ajtmh.19-0496

Abstract

.All Plasmodium cases have declined over the last decade in northwestern Thailand along the Myanmar border. During this time, Plasmodium vivax has replaced Plasmodium falciparum as the dominant species. The decline in P. falciparum has been shadowed by a coincidental but delayed decline in P. vivax cases. This may be due to early detection and artemisinin-based therapy, species-specific diagnostics, and bed net usage all of which reduce malaria transmission but not P. vivax relapse. In the absence of widespread primaquine use for radical cure against P. vivax hypnozoites, the decline in P. vivax may be explained by decreased hypnozoite activation of P. vivax relapses triggered by P. falciparum. The observed trends in this region suggest a beneficial effect of decreased P. falciparum transmission on P. vivax incidence, but elimination of P. vivax in a timely manner likely requires radical cure.

Highlights

Malaria has decreased in the Greater Mekong Subregion (GMS) over the last decade
Shoklo Malaria Research Unit (SMRU) operates clinics located in Thailand along the Moei River, which forms the border
Malaria smears in the migrant clinics were performed systematically in children aged < 5 years and during a one-week period each month.[6]

Summary

Introduction

Malaria has decreased in the Greater Mekong Subregion (GMS) over the last decade. The WHO estimates that from 2012 to 2015, malaria cases declined by 54% and malariarelated mortality by 84% in this region. Plasmodium falciparum malaria has decreased along the Thailand–Myanmar border over the last decade.[4] Without widespread radical cure, a different pattern might be expected for P. vivax.

Results

Conclusion