Trend of Cholera in the Last 50 Years and Modeling the Effect of Annual Temperature and Rainfall on Incidence of New Outbreaks in Iran (2005-2014)

Cholera is one of the public health ththat has received attention due to climate change and weather variables. In the current study, the trend of cholera and its epidemics was assessed in the last 50 years in Iran based on climatic variables.
In a retrospective cohort study, all cholera cases and epidemics of the disease in the country (Iran) were assessed using the registry system of the Center for Communicable Disease Control in the Ministry of Health and Medical education (MOH&ME) from 1964 to 2014. Furthermore, the incidence of cholera was evaluated in 2005-2014 by province. The temperature and rainfall data were obtained from the provincial Meteorological Organization. The correlation coefficient test and mixed-effects binomial regression model were used for data analysis.
A significant positive correlation was found between cholera and rainfall (r = 0.168, P = 0.008). A one-millimeter increase in rainfall increased the incidence of cholera by 10.9% but temperature changes had no effect on cholera outbreaks. The incidence of cholera declined significantly by 14.7% each year from 2005 to 2014. The highest incidence of cholera was reported in Sistan-Baluchestan, Qom, Tehran, Kerman and Hormozgan provinces in a descending order.
In recent years, the the overall incidence of cholera has decreased. The occurrence of cholera is an outcome of rainfall in the previous year. Therefore, increased rainfall increases the number of cholera cases in the next year. However, temperature changes are not related to cholera outbreaks.