University of Tabriz Journal of Zoonotic Diseases 2476-535X 10 1 2026 01 01 Prevalence of Salmonella and Edwardsiella spp. in Nile Tilapia (Oreochromis niloticus) sold in some retail fish markets in Tehran, Iran 1084 1091 20894 10.22034/jzd.2025.20894 EN Hannaneh Sadat Emadi Department of Veterinary Medicine, SR. C., Islamic Azad University, Tehran, Iran Abbasali Motallebi Department of Food Hygiene, SR. C., Islamic Azad University, Tehran, Iran 0000-0002-6805-3075 Journal Article 2025 09 02 Salmonella spp. and Edwardsiella spp. are major zoonotic pathogens associated with seafood, responsible for foodborne illnesses and significant public health risks. This study investigated their prevalence in Nile tilapia (Oreochromis niloticus) sold in retail fish markets in Tehran, Iran. A total of 108 samples were collected in autumn 2024, including 68 fresh whole fish, 24 imported frozen fillets from the main market, and 16 fresh samples from retail outlets. Two skin swabs were taken from each fish and analyzed according to ISO 6579-1:2017 standards, using selective enrichment, bacteriological plating, and biochemical confirmation. Initial screening suggested Salmonella in 48 samples (44.4%) and Edwardsiella in 8 (7.4%). Confirmatory testing identified Salmonella spp. in 8 samples (7.4%): 4 from frozen fillets and 4 from fresh retail fish. Edwardsiella spp. was confirmed in 4 samples (3.7%), all originating from frozen fillets. Statistical analysis showed a significant difference in Edwardsiella contamination between fresh and frozen samples (p = 0.0147). Salmonella contamination also differed significantly between the main market and other retail sources (p = 0.0026). These findings suggest contamination may be linked to poor packaging and non-specialized handling in retail settings. As tilapia is increasingly consumed raw or undercooked, routine microbial monitoring is necessary to protect food safety.

https://jzd.tabrizu.ac.ir/article_20894_8c57f87532d0754147800b627da6400e.pdf