การวิเคราะห์ระบาดวิทยาเชิงพื้นที่และการคาดการณ์พื้นที่อุบัติการณ์ของโรคสครับไทฟัสในอำเภอแม่ฟ้าหลวง จังหวัดเชียงราย

Abstract

Spatial Epidemiological Analysis and Incidence Area Prediction of Scrub Typhus Disease in Mae Fa Luang District, Chiang Rai Province. The objectives of this study are to study the distribution pattern of the incidence of scrub typhus in Mae Fah Luang District Chiang Rai Province, analyse physical factors affecting the incidence of scrub typhus, and predict the incidence of scrub typhus in Mae Fah Luang District Chiang Rai by creating of a regression model. We analyse the scrub typhus incidence data in Mae Fah Luang District Chiang Rai Province, in terms of area and population, covering the period 2014 to 2018. We use the Average Nearest Neighbor Index and Kernel Density Estimation to analyse the point pattern of the cases. The analysis was performed using Landsat-8 OLI satellite imagery. The physical factors were determined, including NDVI, NDWI, temperature, elevation, and land use. These factors were then analysed by Pearson's correlation coefficient. The data of physical factors were used as the independent variable to create the predicted Scrub Typhus Incidence model. The results showed that Scrub Typhus Incidence is scattered in many areas. Most of the outbreak areas were in the north of Mae Fah Luang District and decreased as they approached Mueang Chiang Rai District. Scrub Typhus cases happen more in areas adjacent to the edge of the forest, such as Mae Fah Luang District. In addition, the distribution is a random pattern from January-May and clustered pattern from June-December. The incidences were spread, and the severity of the disease increased in June-December, the highest in the rainy season, winter and summer, respectively. The critical areas from the density analysis were Ban Thoet Thai, Ban Hin Taek, Ban Huai Eun, and Ban Thoet Thai Nueng, respectively. In particular, the regression model had relationship with NDVI (0.5-0.6), NDWI ((-0.7)-(-0.5)), temperature (20-26 °C), elevation (400-1000 meters MSL), Landuse (forest-grass-shrub) with R2 of 0.761. The above results show the importance of spatial analysis, which would be useful for other rural areas, sparsely populated areas surrounded by forests near the border, depending on the spatial heterogeneity of outbreaks of scrub typhus.