Objective: To explore the spatial and temporal characteristics of human brucellosis in Shandong province and to provide scientific basis for the development of related regional public health strategies.
Methods: 1 802 diagnosed cases of human brucellosis patients were selected based on the data that was collected by Diseases Reporting Information System between year 2004 and 2012 in Shandong province. Methods on spatial thematic mapping, spatial autocorrelation analysis, spatial clustering analysis, and temporal clustering analysis were applied to describe the temporal and spatial distribution on human brucellosis cases.
Results: The incidence rate of human brucellosis increased from 0.038 2/100 000 (35 cases) to 0.620 5/100 000 (598 cases), with annual average incidence rate as 0.211 1/100 000 and the incidence was evidently increased. The value of M (0.375 3) showed that this disease was seasonal, with the epidemic months between March and June, accounting for 56.27% (1 014/1 802). The Global Moran's I index was 0.198 901 (P = 0.000 120), showing that there was a positive correlation between space and the incidence of brucellosis. The incidence rates in 2006, 2007, 2009 and 2012 and the space distribution appeared a positive correlation (P < 0.05) in Shandong province. The local Moran's I index showed that there were 8 "High-High" (HH) clustering areas, which were proved to have statistical significance (P < 0.05). Local indicators of spatial association (LISA) revealed that southwest and north districts of Shandong were highly clustered districts of brucellosis and the areas paralleled to the areas that having higher incidence rates. There were two spatial clustering areas in this study, one as the center of Juanchen with radiation radius at 33.83 km whose RR was 9.78 (P < 0.05) and the other was the center of Binchen with radiation radius at 62.78 km with RR as 4.99 (P < 0.05). All the 8 HH counties (districts) were included in the two cluster regions.
Conclusion: Incidence of human brucellosis showed an obvious increase in Shandong during year 2004-2012. Months with epidemics were between March and June. The incidence of brucellosis in counties (districts) was non-randomly distributed. A positive spatial correlation and the feature of clusters was noticed.