05) in both cities, which indicated that climatic conditions differed between the months with or without floods. During the flooded months, the morbidity of dysentery was higher than the non-flooded months, followed by more precipitation, higher temperature, higher relative humidity and more sunshine duration. Fig. 2 shows that the morbidity of dysentery declined from 2004 to 2009, and more cases occurred in spring and summer in these cities. Table 4 shows the results of Spearman’s correlation test conducted to determine
the lagged effects between the morbidity of dysentery and explanatory check details variables during the study period in each city. The results indicated that the floods were positively correlated to the monthly morbidity of dysentery with no month lagged among the three cities. The lagged values of climatic variables in these cities were the same except for the monthly average temperature
in Kaifeng according to the coefficients in Table 4. The parameters of the models and RRs of floods on the risk of dysentery are presented in Table 5. Results showed that floods were significantly associated with the morbidity of dysentery in each of the three cities (Coefficients: 2.44 in Kaifeng; 0.30 in Xinxiang; and 1.01 in Zhengzhou). However, flood duration was negatively correlated with the morbidity of dysentery (Coefficients: −0.63 in Kaifeng; −0.50 in Xinxiang learn more and −0.36 in Zhengzhou). During the flooded months, floods were significantly associated with an increased risk of dysentery with adjustment for meteorological factors in Kaifeng (RR = 11.47, 95% CI: 8.67–15.33). The RRs of dysentery for floods in Xinxiang and Zhengzhou were 1.35 (95% CI: 1.23–3.90) and 2.75 (1.36, 4.85), respectively. In addition, the overall effects of Oxalosuccinic acid floods on dysentery in the entire region were estimated through the overall function. As shown in Table 6, an increased risk of dysentery in this region was found, which indicated that floods could increase the
morbidity of dysentery in flooded months (RR = 1.66, 95% CI: 1.52–1.82). This overall model also indicated the extent of dysentery epidemics in the cities. Compared with Kaifeng city, the intensity of dysentery epidemic in Zhengzhou was the greatest with the highest morbidity in terms of the coefficients of the model (Coefficient: 1.13, 95% CI: 1.11–1.16), followed by Xinxiang with lower intensity and morbidity (Coefficient: 0.19, 95% CI: 0.15–0.22). Our study is the first time to demonstrate the quantitative risk of the relationship between the morbidity of dysentery and floods on the basis of a longitudinal data from 2004 to 2009. The results indicated that floods play an important role in the dysentery epidemics during the flood-month.