Abstract
Background and aims: Shigellosis or bacillary dysentery is an infectious disease transmitted through
water and food. It is a type of infectious colitis caused by Shigella bacteria. The aim of this study is to
determine the prevalence and the spatial distribution of shigellosis and its relationship with climatic
factors in Chaharmahal and Bakhtiari province.
Methods: In this study, population of infected people to shigellosis in the province during 2011 to
2014 obtained from reliable sources and analyzed. The statistics were standardized for every city in
the event of illness per hundred thousand people. The relationships between incidence of the disease
and the climatic factors (temperature, rainfall and humidity) were investigated by Pearson correlation
coefficient after generation of zonation map using GIS and analysis of the concentration centers.
Results: According to the results, Koohrang, Lordegan and Ardal cities are classified as high risk areas
with an incidence more than 400000 people. Borujen and Faarsan cities are medium risk areas with
an incidence less than 250 per 100000, and Shahr-e-kord city with an incidence less than 100 per
100000 people is considered a low risk area. The incidence grows with increase in the temperature.
Increase in the precipitation and humidity decreases incidence of the disease. Concentration and
prevalence of shigellosis mostly occur in west of the province, because this area is located in the
neighborhood of Khuzestan province, and also due to nomadic residence of Bakhtiari nomads in
this part during summer and their unhealthy lifestyle, limited access to treated water and especially
consumption of untreated surface water. The higher concentration of nomadic residence and higher
contamination of water increase incidence of waterborne diseases. The frequency increase of the
disease in warm seasons can be due to prevalence of Shigella dysentery in the region.
Conclusion: Based on the results, significant positive correlations exist between the surface water
consumption, the temperature increase, the number of pisciculture centers in the area and incidence
of the disease. Significant negative correlations are also observed between the rainfall, humidity and
incidence of the disease.