# Impact of intensive control on malaria population genomics in Eastern Myanmar

## TL;DR

Malaria control efforts in Eastern Myanmar have significantly reduced transmission and altered parasite genetic diversity.

## Contribution

This study provides genomic evidence of malaria control impacts, including parasite population structure changes and localized transmission patterns.

## Key findings

- Malaria control reduced transmission by 97% and decreased parasite genetic diversity.
- Localized transmission of unique parasite genotypes was observed within 20 km.
- Mass drug administration caused parasite founder effects and reduced effective population size.

## Abstract

The malaria elimination program in Kayin State (Myanmar) utilizes malaria posts
for rapid detection and treatment together with mass drug administration (MDA) in high
transmission villages, and has reduced transmission by 97%. We examined the impact of
control on parasite genomic parameters, using 2270 genome sequenced Plasmodium falciparum
infections from 283 malaria posts, sampled over 58-months (2015 – 2020). Parasites
were genetically depauperate: 1726 single-genotype infections comprised 166 unique genomes
(≥90% IBD), while nine families (≥45% IBD) accounted for 62.5% of parasites
sampled. Parasite effective population size decreased over the study period, but there was
minimal change in artemisinin resistance alleles until 2020, when just one predominant
genotype (carrying kelch13-R561H) remained. We observed sustained localized transmission
of unique parasite genotypes revealing transmission chains: this resulted in positive
correlations in parasite relatedness for ≤20 km. MDA resulted in parasite founder
effects, providing genomic evidence for the efficacy of this control tool. These results
reveal changes in population structure driven by control, and rapid shifts in allele
frequency in a parasite population close to elimination.