Spatial and temporal distribution characteristics of varicella epidemic in Jiading District in Shanghai from 2015 to 2018

ObjectiveTo investigate the spatial-temporal distribution characteristics of varicella outbreak in Jiading District in Shanghai from 2015 to 2018.

MethodsVaricella epidemic report data was collected from the national system of disease control and prevention and analyzed by spatial-temporal scanning statistic methods.

ResultsThere were 5 889 varicella cases reported from the year 2015 to 2018, and the annual average incidence rate was 91.68 per 100 000.The incidence rate for children below 3 years old was found to be the highest, reaching 621.45 per 100 000, which was significantly higher than that for the group of 18 years old and above (χ²=16 616.788, P < 0.001).There were 5.41% and 5.31% of the cases in September and February, respectively, which were lower than other months, and the peak incidence occurred in December and November, accounting for 13.41% and 11.95%, respectively.The highest and lowest incidence rates were 151.80 per 100 000 occurring in central urban area and 59.89 per 100 000 in rural area, respectively.The spatial-temporal scanning showed that the low population density area had a wide cluster range and a low effect value.The high population density area has small cluster range and high effect value.

ConclusionThe incidence of vanicella presents a trend of population, seasonal and regional clustering.Therefore, targeted measure should be taken to prevent varicella in focus population.