Study Of Spatio-temporal Trends Of Malaria Incidence And Environmental Predictors Of Malaria Transmission In Myanmar

Objective: Myanmar is the country with the highest malaria burden in the Greater Mekong Subregion（GMS）of Southeast Asia,and the distribution of malaria presents spatial heterogeneity.The objective of this study was to investigate the spatial distribution pattern of malaria incidence in Myanmar,to assess the temporal and spatial dynamics of Plasmodium falciparum and Plasmodium vivax in Myanmar.At the same time,the challenges facing China as a neighboring country in moving from malaria control to elimination are identified.Methods : Annual and monthly reports of malaria cases in primary health centers from 2011 to 2017 were analyzed,and the distribution of malaria,incidence hot/cold spots,cluster areas,and cluster time in townships and districts in Myanmar were described by spatial autocorrelation（Moran index）and spatio-temporal cluster analysis.The environmental predictors of P.falciparum and P.vivax were determined by negative binomial generalized additive model.GeoDa 1.14.0 software was used to calculate plasmodium smoothing incidence,Moran index and local indicator statistics;Calculate cluster scan statistics using SaTScan^TM 9.3.All maps were generated using QGIS 3.10.1.Results : 1.From 2011 to 2017,both the incidence and positive rate of malaria in Myanmar decreased significantly overall.The incidence of malaria peaks in June each year.The states of Chin,Kachin and Rakhine had the highest incidence of malaria in all years except 2012.There were significant spatial autocorrelation and extreme spatial heterogeneity clusters in malaria cases and positive cases（P < 0.05）.2.The areas with higher rates of both types of malaria are concentrated along international borders.P.falciparum persists in western townships,with high annual incidence confined to the northern and western parts of Chin,Kachin and Sagaing states.The number of townships covered by the main cluster decreased from 19 in 2011 to 1 in2017,with the northwestern region being a significant secondary cluster area.During the study period,the villages with high annual incidence of P.vivax were confined to the western,northern and south-eastern of Chin,Kachin and Kayah states.The main cluster changed significantly geographically,with the number of villages covered by the main cluster decreasing from 37 in 2013 to 1 in 2017.In the past two years,characteristics of secondary clusters appeared in the northern region.The main spatio-temporal cluster was discovered between January 2011 and December 2013,covering two states（Sagaing and Kachin）3.Annual malaria incidence was highest in townships with a mean elevation of 500-600 m and a high variance in elevation（states with both high and low elevation）.There was an apparent linear relationship between the mean normalized difference vegetative index and annual P.falciparum incidence（P < 0.05）.Conclusion: During the study period,the incidence of malaria in Myanmar showed a significant downward trend due to social,environmental,economic and other factors,but there were still clusters in some areas,among which falciparum malaria was the main disease in the northwest and vivax malaria in the northeast.In the next step,resources should be allocated to the high-risk areas identified in this study in order to achieve more efficient disease control.At the same time,it suggests that epidemic prevention authorities in China should strengthen malaria detection along the China-Myanmar border to guard against the challenge of imported cases in the high incidence area of vivax malaria in northeastern Myanmar.