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Abstract Background and Objective: The patients with Post-Infectious Irritable bowel syndrome (PI-IBS), a subtype of irritable bowel syndrome, suffer from bacterial gastroenteritis. Since campylobacter Jejuni (CJ) is one of the most common agents in this syndrome, we aimed to evaluate the prevalence of Campylobacter Jejuni in patients with Irritable Bowel Disease. Material and Methods: This case - control study was conducted on 160 patients divided into 2 equal groups of healthy and unhealthy. The presence of Anti- CJ antibody (IgG and IgA) was evaluated by ELISA and the comparison was performed by chi-square test. Results: The mean age of case (31.51) and control (31.84) was not statistically different (P = 0.87). Titer of Anti- Campylobacter Jejuni antibody IgG was positive in 25% of patients and 18.8% of the healthy ones (p=0.02). IgA Seropositivity in patients was 7.5% but no one in control group was positive (p =0.01) Conclusion: Seroprevalence of Cj in patients with IBS was higher significantly than that of control group. Thus, Cj can be known as one of the causes of Post-infection in patients with IBS in our region and it should be paid more attention in diagnostic assessment of these patients. Keyword: Irritable Bowel Syndrome Campylobacter Jejuni Antibody

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