An Epidemic of Shigella Flexneri and its Related Factors in Isfahan in Spring 2015: A Case? Control Study

Epidemics of diarrhea caused by contaminated food and water occur frequently worldwide, especially in developing countries. The aim of this study was to identify the factors contributing to the development and spread of diarrhea epidemics caused by Shigella flexneri in Isfahan in the spring of 2015.

Following the first reports and activation of the surveillance system, a matched case-control study was conducted in 360 cases with diarrhea and 360 controls. Data were gathered using a questionnaire, and conditional logistic regression was used to provide adjusted odds ratios and 95% confidence intervals.

Consumption of contaminated fresh vegetable (OR=4.50, 95% CI=2.88-7.01) was the source of the epidemic. Contact with similar patients (OR=7.19, 95% CI=4.26-12.12), presence of similar patients in the family (OR=33.2, 95% CI=13.64-80.82), food consumption on special events (party, wedding ceremony, funeral, etc.) (OR=1.67, 95% CI=1.06-2.62), being a government employee (OR=3.08, 95% CI=1.64-5.78) and being illiterate (OR=2.91, 95% CI=1.10-7.67) were the risk factors of the spread of the epidemic.

In this study, consumption of fresh vegetable contaminated with Shigella flexneri was the source of the infection. According to the Epidemic Management Team, contamination occurred due to non-standard wastewater irrigation of agricultural lands. Therefore, it is important to consider the standards of agricultural production and compilation of a comprehensive program to improve the status of the wastewater purification system in the environmental sciences by the relevant organizations to prevent diarrhea epidemics