鄱阳湖区南昌县血吸虫疫情空间分布及其流行因素分析

Spatial Analysis on Epidemic Factors of Schistosomiasis in Nanchang County over the Coast of Poyang Lake

南昌县是鄱阳湖沿岸血吸虫流行区最主要的区域之一,是江西省血防工作的重点区域。结合疫水接触强度、村内耕牛数量、村到鄱阳湖边界的距离、村内湖岸线的长度等数据,通过传统线性回归、空间滞后回归模型、空间误差回归模型研究了2009年南昌县血吸虫疫情空间分布特点及其流行因素。结果表明:1)2009年南昌县血吸虫疫情主要分布在东北、东南部鄱阳湖沿岸、赣江流域沿岸等村域,疫水接触强度空间分布与疫情分布具有明显的一致性;2)单因素分析表明村内居民的疫水接触强度、村内耕牛数量、村内湖岸线长度、村到鄱阳湖边界的平均距离与病人数都具有明显的相关性,其中病人数和行政村到鄱阳湖沿岸的距离呈负相关性;3)3种回归模型拟合结果表明居民的疫水接触强度、村内耕牛数量、村到鄱阳湖边界的距离是影响南昌县血吸虫病人数分布的主要因子,以上3个指标可以解释总变异的81%。

Schistosomiasis is a kind of parasitic disease which may happen between humans and animals. Nangchang County is one of the most serious region, where schistosomiasis happens over the coast of Poyang Lake. Nowadays, this county has become the key area of schistosomiasis prevention and control in Jiangxi Province. As the suspending of loan from WHO, the investment that used for schistosomiasis prevention and control is decreasing in Nangchang County. For benefit maximization, it has become important that how to make full use of the limited resources. Many previous researches indicated that exploring the gathered area of schistosomiasis is the best way to solve the above problem. In this paper, basic data from 86 villages in 2009 are collected, including the number of patient, total population, the number of cattle, etc. In addition, the administrative map of Nangchang County is digitalized and the geometric centers of the 86 villages are extracted. And then the boundary line through the TM image taken in June 2009 was extracted. Single factor analysis of correlation model, traditional linear regression models, spatial lag model and spatial error model were employed for quantitative analysis of those data. The results of spatial analysis indicated that the spatial distribution of the infection rates of administrative villages was greatly uneven, the main endemic villages were distributed near the northeast and southeast coast of Poyang Lake and the Ganjiang River basin in 2009. In addition, there existed obviously consistency between the spatial distribution of the intensity of water contact by the residents and that of schistosome epidemic. In this study, spatial error of regression is employed to analyze the relationship between the water contact index and the number of patients. The results show that the water contact index can explain 71% of the total variance of the number of patients, indicating that the calculation method of water contact index in Nanchang County is accurate and applicable more or less. Furthermore, the traditional linear regression model, spatial lag model and spatial error model are used to quantitatively measure the endemic factors of schistosomiasis in Nanchang County. The results show that the spatial error regression analysis is very significance. The single factor analysis shows that the four factors are consistent with the number of patients with a high correlation. The number of patients shows decrease with a high negative correlation with the distance from village to Poyang Lake coast. All the three regression model analysis show that the factors including water contact index, the number of cattle, the distance from village to the coast of Poyang Lake are the major epidemic factors, which can explain 81% of the total variance.