Bayesian spatiotemporal analysis of malaria infection along an international border: Hlaingbwe Township in Myanmar and Tha-Song-Yang District in Thailand

Abstract Background One challenge in moving towards malaria elimination is cross-border malaria infection. The implemented measures to prevent and control malaria re-introduction across the demarcation line between two countries require intensive analyses and interpretation of data from both sides, particularly in border areas, to make correct and timely decisions. Reliable maps of projected malaria distribution can help to direct intervention strategies. In this study, a Bayesian spatiotemporal analytic model was proposed for analysing and generating aggregated malaria risk maps based on the exceedance probability of malaria infection in the township-district adjacent to the border between Myanmar and Thailand. Data of individual malaria cases in Hlaingbwe Township and Tha-Song-Yang District during 2016 were extracted from routine malaria surveillance databases. Bayesian zero-inflated Poisson model was developed to identify spatial and temporal distributions and associations between malaria infections and risk factors. Maps of the descriptive statistics and posterior distribution of predicted malaria infections were also developed. Results A similar seasonal pattern of malaria was observed in both Hlaingbwe Township and Tha-Song-Yang District during the rainy season. The analytic model indicated more cases of malaria among males and individuals aged ≥ 15 years. Mapping of aggregated risk revealed consistently high or low probabilities of malaria infection in certain village tracts or villages in interior parts of each country, with higher probability in village tracts/villages adjacent to the border in places where it could easily be crossed; some border locations with high mountains or dense forests appeared to have fewer malaria cases. The probability of becoming a hotspot cluster varied among village tracts/villages over the year, and some had close to no cases all year. Conclusions The analytic model developed in this study could be used for assessing the probability of hotspot cluster, which would be beneficial for setting priorities and timely preventive actions in such hotspot cluster areas. This approach might help to accelerate reaching the common goal of malaria elimination in the two countries

SPATIO-TEMPORAL ANALYSIS OF MALARIA INCIDENCE ALONG HLAINGBWE TOWNSHIP IN MYANMAR AND THA SONG YANG DISTRICT IN THAILAND

Background: Malaria stays a serious public health problem in many countries of the world. The border regions are difficult to control for the malaria elimination due to the importation or reintroduction of malaria. A key to address such problem is reinforcing of surveillance activities with rapid identification.  The objective of the study was to describe the malaria incidence rate and analyze the space and time distribution of malaria incidence rate in the high endemic border areas between Myanmar andThailand, the Hlaingbwe Township and Tha Song Yang District.  Methodology: Daily malaria data were collected, using a passive surveillance system, from patients visiting local health facilities in both Tha Song Yang and Hlaingbwe regions. ArcMap software version 10.4.1 was used to describe the disease mapping of malaria incidence rate in both regions. Results: Compared to their counterparts, male gender had higher malaria incidence rates in both Tha Song Yang and Hlaingbwe regions. Non-Thai people had higher incidence rate than Thai in Tha Song Yang district. The higher incidence rates had seasonal pattern and the pattern was similar in both regions. The areas with a higher incidence rate could be seen in both inner side and along Thai- Myanmar border (upper and lower parts) in Tha Song Yang area. But in Hlaingbwe Township, the higher incidence rate occurred only in the inner and upper parts except for Me La Yaw and Tar Le areas which are situated along the Thai-Myanmar border. Along the border, the higher incidence rates were connected to the adjacent area in upper and lower parts between these two regions. Conclusion: The descriptive statistics and presented map in this study gave the health policy makers an important overview of malaria situation in this regions in order to intervene high risk areas more effectively, and distribute the resources in a useful manner