Pathological and Molecular Investigation of Paratyphoid Salmonella Infection in Broiler Chicks in Sulaymaniyah Province, Kurdistan/Iraq

Paratyphoid infection is a serious-infectious disease of poultry with economic and public health consequences. We investigated paratyphoid Salmonella infections and their associated histopathological changes in broiler chicks in Sulaymaniyah province using molecular, histopathological and immunohistochemical techniques. A total of 130 broiler farms, aged between 1 to 20 days were investigated. The results showed that the prevalence of paratyphoid Salmonella in the region was 28.5%, including Salmonella Enteritidis (70.3%) and Salmonella Typhimurium (29.7%). The rate of infection was higher (76%) among 1-10 days-old chicks in comparison to 11-20 days-old chicks (24%). The distribution of the pathogen was varied among the tested organs, including the caecum (97.3%), liver (91.9%) and yolk-sac (86.5%). The rate of infection by S. enteritidis in 1–10-day-old chicks in the organs was higher (67.9%) than the rate of infection by S. typhimurium in the liver (25%), yolk-sac (25%) and caecum (28.6%). There was a highly significant positive correlation between S. enteritidis and S. typhimurium infections in the liver (r=0.818, P=0.000, n=37). At the same time, a highly significant strong negative correlation between S. enteritidis and S. typhimurium infections was found between the inspected organs. The most obvious pathological changes were degeneration and necrosis of the hepatocytes and sloughing of the caeca epithelium. Claudin-1 expression and distribution among cellular compartments were mostly affected by Salmonella enteritidis-positive cases. The findings of this study showed that there was a widespread paratyphoid Salmonella infection in the region, and associated with severe histopathological and immunohistochemical changes, especially among 1-10 days-old chicks.