A descriptive analysis of the Spatio-temporal distribution of intestinal infectious diseases in China

Mao, Ying; Zhang, Ning; Zhu, Bin; Liu, Jinlin; He, Rongxin

On one hand, we would like to compare the temporal analyses of the six intestinal infectious diseases. According to the incidence rates recorded from 2006 to 2016, the temporal trends differed. Regarding the absolute incidence of cases, the incidence of HFMD was higher than the other IIDs, and it gradually became a wide-spread disease, which is consistent with the results from the study by Zhang [30] . Then, dysentery and OIDD were less severe diseases. Hepatitis A, Hepatitis E and TAP were the least severe diseases, according to the incidence rates. Regarding the trend, the incidence rates of HFMD and Hepatitis E showed a distinct increasing trend, consistent with the results from the study by Zhu. As the epidemic of Hepatitis A was controlled, the percentage of Hepatitis E cases among patients with viral hepatitis and among patients with IIDs has increased. The mortality rate of Hepatitis E has increased among infectious diseases [31] . The trend in the incidence of OIDD was almost unchangeable. Dysentery and TAP displayed obvious decreasing trends. The analysis of dysentery filled the research gap in the study by Xie et al., which showed a decreasing trend in the incidence of dysentery from 2005 to 2010 [32] . The results for TAP were similar to the findings reported by Liu [33] , which showed a decreasing trend. The improvement in sanitation facilities and the reduction in food and water pollution likely contributed to the decreasing trend in the incidence rates of these diseases. Hepatitis A exhibited a slight increasing trend in the first 2 years, followed by a decreasing trend. This result was similar to the findings reported by Zhu [19] . In conclusion, class B diseases were prevented with high efficiency. Class C diseases experienced a higher incidence rate and gradually increasing trend. Regarding the seasonal changes, the incidence of HFMD and dysentery peaked in the summer, Hepatitis E exhibited a high-incidence season in spring, OIDD peaked in summer and a smaller peak in autumn, the peak incidence of Hepatitis A occurred in summer and spring, and a distinct peak for TAP was not observed. Previous studies have revealed an association between the IIDs and seasons [16, [34] [35] [36] [37] . The occurrence of intestinal infectious diseases is related to climatic factors, such as the sunshine duration, temperature and humidity, as well as the quality of food and drinking water [38] . Due to the high temperature and humidity in summer, which are conducive to bacterial reproduction, food and water are easily contaminated. At the same time, the human immune system is relatively weak due to higher bodily exertion in summer. In conclusion, summer is the season with the highest incidence rates for IIDs and should receive closer attention.