Molecular markers of artemisinin resistance during falciparum malaria elimination in Eastern Myanmar

Abstract

Background: Artemisinin resistance in Plasmodium falciparum threatens global malaria elimination efforts. To contain and then eliminate artemisinin resistance in Eastern Myanmar a network of community-based malaria posts was instituted and targeted mass drug administration (MDA) with dihydroartemisinin-piperaquine (three rounds at monthly intervals) was conducted. The prevalence of artemisinin resistance during the elimination campaign (2013-2019) was characterized.

Methods: Throughout the six-year campaign Plasmodium falciparum positive blood samples from symptomatic patients and from cross-sectional surveys were genotyped for mutations in kelch-13-a molecular marker of artemisinin resistance.

Result: The program resulted in near elimination of falciparum malaria. Of 5162 P. falciparum positive blood samples genotyped, 3281 (63.6%) had K13 mutations. The prevalence of K13 mutations was 73.9% in 2013 and 64.4% in 2019. Overall, there was a small but significant decline in the proportion of K13 mutants (p < 0.001). In the MDA villages there was no significant change in the K13 proportions before and after MDA. The distribution of different K13 mutations changed substantially; F446I and P441L mutations increased in both MDA and non-MDA villages, while most other K13 mutations decreased. The proportion of C580Y mutations fell from 9.2% (43/467) before MDA to 2.3% (19/813) after MDA (p < 0.001). Similar changes occurred in the 487 villages where MDA was not conducted.

Conclusion: The malaria elimination program in Kayin state, eastern Myanmar, led to a substantial reduction in falciparum malaria. Despite the intense use of artemisinin-based combination therapies, both in treatment and MDA, this did not select for artemisinin resistance.

Keywords: P. falciparum; Artemisinin resistance; Kelch13; Malaria elimination; Mass drug administration.

Fig. 1

Location of collected P.falciparum genotyped specimen

Fig. 2

Annual symptomatic P.falciparum/Pmix incidence per thousand persons per year from 2014 to 2019 diagnosed and treated by malaria posts

Fig. 3

Annual proportion of P. falciparum isolates with K13 mutations during the six-year programmes. Circled areas are proportional to the square root of the sample size

Fig. 4

Proportion of K13 mutations from 2013 to 2019. The y-axis represents K13 mutants proportion with 95% confidence intervals while the x-axis denotes the years from 2013 to 2019. ^#K13 mutations where the association with parasite clearance has not yet been established. The uncharacterized mutations are A621V, A626S, C469F, C469Y, C542Y, D109Y, D452E, D584V, E208K, E321K, F614L, G533A, G533D, G533S, G718S, I205T, K189T, K438N, K479I, K586E, M562I, N264I, N490H, N525Y, R265P, R528S, R529G, R575K, S423N, T192I, T535M, V193E, V494I, V534G, W611C

Fig. 5

Proportion of K13 mutations from 2013 to 2019. A Hpapun, B Kyainseikgyi and C Myawaddy, Kawkareik and Hlaingbwe. ^#K13 mutations where the association with parasite clearance has not yet been established. The uncharacterized mutations are A621V, A626S, C469F, C469Y, C542Y, D109Y, D452E, D584V, E208K, E321K, F614L, G533A, G533D, G533S, G718S, I205T, K189T, K438N, K479I, K586E, M562I, N264I, N490H, N525Y, R265P, R528S, R529G, R575K, S423N, T192I, T535M, V193E, V494I, V534G, W611C

Fig. 6

Proportion of K13 mutations comparison in MDA and non-MDA villages from 2013 to 2019. ^#Uncharacterized mutations are K13 mutations where the association with parasite clearance has not yet been established