A Survey of Probable Risk Factors for Cholera Outbreak in Qom, Central Iran, in 2017

Cholera is one of the communicable diseases that should be reported immediately as a public health threat. This study was conducted to study the probable risk factors of cholera outbreak in Qom, central Iran, during 2017.   In a case-control study, 37 cholera patients diagnosed based on para - clinical tests and 37 control samples were evaluated. Charts, frequency tables, regression logistic, Chi-square and t-test in SPSS software ver.25 were used for data analysis. The causative agent in the Qom cholera outbreak was Vibrio cholerae serotype Inaba. Most of the patients (54%) were in the age range 21-40 years. Most of the cholera cases were males (87%), Iranians (81%), and school or college students (30%). The peak of the epidemic occurred in the third week of November 2017, coinciding with a religious event. Nearly half of the patients were identified at the cross-border surveillance centers. The most important risk factors for the outbreak were a history of travel to Iraq in order to attend the Arbaeen religious event (95%), (OR=75, P-value<0.001), and a history of consuming unreliable foods and water (94% and 50%, (OR=66, CI=8-410, P-value=0.00 and OR=11, CI=2.7-46)), respectively.    Cross-border surveillance of cholera in common borders with Iraq, especially in the Arbaeen religious event, played a vital role in identifying patients suspected of cholera. The surveillance of communicable diseases should be strengthened when entering and leaving the Arbaeen event.