Effects of the floods on dysentery in north central region of Henan Province, China from 2004 to 2009

Objectives: Zhengzhou, Kaifeng and Xinxiang, the cities in the north central region of Henan Province, suffered from many times floods from 2004 to 2009. We focused on dysentery disease consequences of floods and examined the association between floods and the morbidity of dysentery, based on a longitudinal data. Methods: A generalized additive mixed model was conducted to examine the relationship between the monthly morbidity of dysentery and floods from 2004 to 2009 in the study areas. The relative risks (RRs) of the floods risk on the morbidity of dysentery were estimated in each city and the whole region. Results: The RRs on dysentery were 11.47 (95% CI: 8.67-15.33), 1.35 (95% CI: 1.23-3.90) and 2.75 (95% CI: 1.36-4.85) in Kaifeng, Xinxiang and Zhengzhou, respectively. The RR on dysentery in the whole region was 1.66 (95% CI: 1.52-1.82). Conclusions: Our study confirms that flooding has significantly increased the risk of dysentery in the study areas. Additionally, we observed that a sudden and severe flooding can contribute more risk to the morbidity of dysentery than a persistent and moderate flooding. Our findings have significant implications for developing strategies to prevent and reduce health impact of floods. (C) 2014 The Authors. Published by Elsevier Ltd on behalf of the The British Infection Association. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).