Spatial Clustering Analysis Of Echinococcosis In Ganzi Tibetan Autonomous Prefecture, Sichuan Province

Echinococcosis is a zoonotic parasitic disease caused by the metacestode Echinococcus. Cystic echinococcosis and alveolar echinococcosis are both epidemic in our country. The epidemic of echinococcosis is severity in Ganzi Tibetan Autonomous Prefecture, Sichuan Province. Two types of echinococcosis are both severe epidemic in this area. This situation has attracted considerable attention of all sectors of society. Both the central and local government has strengthened the control and prevention work of echinococcosis in Ganzi Tibetan Autonomous Prefecture. The urgent problems to be solved in present is how to effectively carry out the control and prevention work of echinococcosis.Objective To analyse the spatial distribution pattern and spatial clusters of echinococcosis in Ganzi Tibetan Autonomous Prefecture, Sichuan Province. To explore key area of echinococcosis control and prevention and provide guidance to echinococcosis control and prevention as well as management.Methods ①The screening data of echinococcosis among the population of 18 counties,325 towns during 2008-2014 was collected. Previous endemic situation database and present endemic situation database were then settled. Excel software was used to calculate the detection rate of echinococcosis, cystic echinococcosis and alveolar echinococcosis both in the previous endemic situation database and present endemic situation database. Pearson χ2 test was used to identify the difference between detection rates in different types of manufacturing(town, farming, farming-pastoral, pastoral). ②Ordinary Kriging interpolation was used to estimate the detection rate of towns which were unscreened.③ArcGIS software was used for thematic mapping, the distribution characters of detection rate in different areas of the previous and present were visually displayed.④Spatial scan statistics including the circular spatial scan statistic proposed by Kulldorff("SaTScan" hereafter) and the flexibly shaped spatial scan statistic proposed by Tango("FleXScan" hereafter) and spatial autocorrelation statistics:Moran’s 1 statistic and Getis-Ord G statistic were used to detected the spatial clusters in this Autonomous Prefecture.Results ①In the previous, the highest detection rate of echinococcosis, cystic echinococcosis and alveolar echinococcosis were Niduo town, Seda county 41.67%(150/360), Maqiong town, Baiyu county 21.15%(48/227), Niduo town, Seda county 22.78%(82/360) respectively. In the present, the highest detection rate of echinococcosis, cystic echinococcosis and alveolar echinococcosis were all in Rangu town, Dege county, with the rate of 7.36%(55/747),5.22%(39/747) and 2.14%(16/747) respectively. Compared with different types of manufacturing, the pastoral region had the highest detection rate of echinococcosis, cystic echinococcosis and alveolar echinococcosis, with the rate of 4.79%(χ2=6713.89, P<0.01),3.04%(χ2= 3997.96, P<0.01),1.85%(χ2= 2766.18, P<0,01) respectively in the previous endemic situation and 033%(χ2=361.01, P<0.01),0.22%(χ2=210.51, P<0.01),0.12%(χ2=164.33, P<0.01) respectively in the present endemic situation. ②According to the result of ordinary Kriging interpolation in the 29 unscreened towns in the previous, the detection rate of echinococcosis, cystic echinococcosis and alveolar echinococcosis varied from 0.02% to 2.25%,0.04%～0.83%,0-0.04% respectively. In the 22 unscreened towns in the present, the detection rate of echinococcosis cystic echinococcosis and alveolar echinococcosis varied from 0-0.25%,0.01%-0.18%, 0-0.04% respectively. ③ The results of spatial clustering analysis indicated that in the previous, spatial clusters of high detection rate of echinococcosis and cystic echinococcosis were located in the central and southeast of Shiqu county, northwest of Seda county, middle and east part of Baiyu county. Spatial clusters of high detection rate of alveolar echinococcosis were located in the central and north of Shiqu county, the borderline on the northeast of Dege county and Shiqu county, north of Seda county. In the present, the spatial clusters of high detection rate of echinococcosis, cystic echinococcosis and alveolar echinococcosis were located in the same area. The center was Shiqu county, the northeast of Dege county, the northwest of Ganzi county were also included.Conclusion In the present, echinococccosis is highly endemic in the pastoral region in Ganzi Tibetan Autonomous Prefecture, Sichuan Province. Clusters were identified on the spatial distribution of echinococcosis in Ganzi Tibetan Autonomous Prefecture, spatial clustering analysis can find out the areas of spatial clusters which are the key areas of echinococcosis control and prevention. In future, more echinococcosis screening work should be carried out in the area of Shiqu county, the northeast of Dege county and the northwest of Ganzi county. To confirm the key area of echinococcosis control and prevention can make echinococcosis control and prevention work more pertinence, improve the effect of echinococcosis control and prevention.