Prevalence and seroprevalence of Plasmodium infection in Myanmar reveals highly heterogeneous transmission and a large hidden reservoir of infection.

Hannah M Edwards ,Celine Zegers De Beyl ,Myaing M Nyunt ,Mousumi Rahman ,Thiri San ,Thaung Hlaing ,Siddhi Aryal ,Thandar Lwin ,Kay Thwe Han ,O Celhay ,Zaw Lin ,Prudence Hamade ,Ruth Dixon ,Chris Drakeley ,Christopher V Plowe ,Arantxa Roca-Feltrer ,Gillian Stresman ,Moe Myint Oo ,Tom Hall ,Aung Thi

doi:10.1371/journal.pone.0252957

Abstract

Malaria incidence in Myanmar has significantly reduced over recent years, however, completeness and timeliness of incidence data remain a challenge. The first ever nationwide malaria infection and seroprevalence survey was conducted in Myanmar in 2015 to better understand malaria epidemiology and highlight gaps in Annual Parasite Index (API) data. The survey was a cross-sectional two-stage stratified cluster-randomised household survey conducted from July-October 2015. Blood samples were collected from household members for ultra-sensitive PCR and serology testing for P. falciparum and P. vivax. Data was gathered on demography and a priori risk factors of participants. Data was analysed nationally and within each of four domains defined by API data. Prevalence and seroprevalence of malaria were 0.74% and 16.01% nationwide, respectively. Prevalent infection was primarily asymptomatic P. vivax, while P. falciparum was predominant in serology. There was large heterogeneity between villages and by domain. At the township level, API showed moderate correlation with P. falciparum seroprevalence. Risk factors for infection included socioeconomic status, domain, and household ownership of nets. Three K13 P. falciparum mutants were found in highly prevalent villages. There results highlight high heterogeneity of both P. falciparum and P. vivax transmission between villages, accentuated by a large hidden reservoir of asymptomatic P. vivax infection not captured by incidence data, and representing challenges for malaria elimination. Village-level surveillance and stratification to guide interventions to suit local context and targeting of transmission foci with evidence of drug resistance would aid elimination efforts.

Highlights

The incidence of malaria in Myanmar has reduced significantly in recent years, falling by over 80% from a reported 1341.8 cases per 100,000 population in 2005 to 253.3 cases per 100,000 population in 2014 [1]
Myanmar has the highest incidence of any country in the Greater Mekong Sub-region (GMS), evidence of artemisinin resistance, challenges of highly mobile population groups, remote and hard-to-reach areas of high transmission and outdoor biting vectors presenting obstacles to meeting this malaria elimination goal [4,5,6,7]
We present results from this survey in relation to geography, incidence data and associated risk factors to better understand the epidemiology of malaria in Myanmar and the challenges faced by drug resistance and malaria elimination

Summary

Introduction

The incidence of malaria in Myanmar has reduced significantly in recent years, falling by over 80% from a reported 1341.8 cases per 100,000 population in 2005 to 253.3 cases per 100,000 population in 2014 [1]. Malaria mortality fell by over 90% from 3.79 deaths per 100,000 to 0.25 per 100,000 over the same period. This trend reflects a corresponding increase in political and financial commitment from the Myanmar government and partners. Myanmar has the highest incidence of any country in the GMS, evidence of artemisinin resistance, challenges of highly mobile population groups, remote and hard-to-reach areas of high transmission and outdoor biting vectors presenting obstacles to meeting this malaria elimination goal [4,5,6,7]. Completeness and timeliness of collation of surveillance data remains a significant challenge in some regions, those that are remote and the true incidence of malaria in the country may, be underestimated [8]

Methods

Results

Conclusion