Estimation on local transmission of malaria by serological approach under low transmission setting in Myanmar

Myat Htut Nyunt,Won Sun Park,Myat Phone Kyaw,Ji-Hoon Park,Than Naing Soe,Ni Ni Zaw,Fauzi Muh,Eun-Taek Han,Seong-Kyun Lee,Seok-Ho Hong,Kwon-Soo Ha,Thinzar Shein,Jin-Hee Han,Soe Soe Han

doi:10.1186/s12936-017-2170-8

Myat Htut Nyunt, Won Sun Park + Show 12 more

Open Access

https://doi.org/10.1186/s12936-017-2170-8

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Abstract

BackgroundAs the prevalence of the malaria has been decreasing in many endemic countries including Myanmar, malaria elimination in Greater Mekong Region was targeted not later than 2030. The relevance of molecular and serological tools to identify residual transmission remains to be established in this setting.MethodsOne-year cohort study was conducted and sera samples were collected in every 3 months with active and passive case detection for clinical malaria episodes by RDT, microscopy and molecular method. The sera were used to detect the malaria antibody against PfMSP1-19, PvAMA1, PvDBPII and PvMSP1-19 by protein microarray.ResultsAmong the recruited 1182 participants, there was no RDT positive case for malaria infection although two vivax infections were detected by microscopy in initial collection. Molecular methods detected the asymptomatic cases of 28/1182 (2.37%) in first, 5/894 (0.42%) in second, 12/944 (1.02%) in third, 6/889 (0.51%) in fourth collection, respectively. Seropositivity rates against the PfMSP1-19, PvMSP1-19, PvAMA1 and PvDBPII were 73/270 (27.0%), 85/270 (31.5%), 65/270 (24.1%) and 160/270 (59.3%), respectively. PfMSP1-19 and PvMSP1-19 showed high and stable antigenicity in acute and subacute samples but declining in 1-year history samples. No cross reactivity of PfMSP1-19 and PvMSP1-19 between the two species and higher seropositivity among the asymptomatic carriers were observed. Mapping data indicated serological surveillance can detect the geographical pattern of malaria infection under low transmission setting.ConclusionsThese findings support that PfMSP1-19 and PvMSP1-19 are suggested for serosurveillance of the malaria especially in low transmission setting for further necessary actions have to be carried out to eliminate the malaria.

Highlights

As the prevalence of the malaria has been decreasing in many endemic countries including Myanmar, malaria elimination in Greater Mekong Region was targeted not later than 2030
Detection of asymptomatic infection All collected samples were checked for asymptomatic parasitaemia by rapid diagnostic tests (RDTs), microscopy and nested PCR
There was no RDT positive case, two cases in visit 1 were detected as P. vivax infections

Summary

Introduction

As the prevalence of the malaria has been decreasing in many endemic countries including Myanmar, malaria elimination in Greater Mekong Region was targeted not later than 2030. In the era of (pre) elimination of malaria, surveillance is vital to estimate the local transmission of malaria [1]. As the parasite densities fluctuate over time, leading to temporal variation in the detectability of infections and cross sectional analysis of the parasitological based detection method cannot estimate the local transmission of malaria correctly. Malaria antibody shows the local transmission profile indicating the indigenous malaria cases in the community [8]. Malaria antibody level was higher in older age assuming the cumulative exposure of the antigens. Significant lower level of malaria antibody was observed in high attitude reflecting the local transmission. Local transmission of malaria can be assessed by malariometric survey and antigen assays as malaria cases are detected throughout the year. Age specific antibody response was reported that may reflect the cumulative exposure or behaviour-related differences in exposure [13]

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Discussion

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