Comparison of PCR and histopathology methods for diagnosis of Yersiniosis infection (yersinia ruckeri) in Rainbow trout of Iran

Yersinia ruckeri is the causative agent of Yersiniosis or Enteric Red mouth Disease that causes huge amount of economic loss in mariculture industry worldwide. Definitive detection and effective treatment for septicemia like Y. ruckeri that outbreak critically, requires rapid and specific diagnosis. Despite the advantages of both PCR and Histopathology techniques in the terms of diagnosis and monitoring they have some defects, the aim of this study is the comparison of PCR and histopathology methods for detection of Yersiniosis in trout fish in Iran.In PCR-based detection, Extracted DNA from suspected Rainbow trout tissue utilized in PCR reaction and polymerase chain products were visualized by gel electrophoresis. In pathological detection, all tissues from live or moribund fish were fixed in 10% formalin saline. Then Samples were embedded in paraffin block and sectioned with digital microtome at 5-7 micrometer thickness. Slides were stained by haematoxillin & eosin, and then treated with mounting media. Differences in the number of positive samples in this comparison demonstrated that each mentioned technique has its advantages so if the advantages of each method exploit and one method supplements the other one, the efficiency and accuracy of monitoring the experiments would boost. In both mentioned methods, all positive results confirmed the existence of yersiniosis infection in Iran, which their comparison is very useful for monitoring and diagnosis of pathogen in the country. Differences in the number of positive samples in this comparison demonstrate that although PCR technique would provide a more rapid and sensitive alternative to traditional diagnosis in detection of harmful pathogens but in some cases such as necrotic and degenerated cells in tissue, PCR ability collapses in the comparison of other detection technique like histopathology. In this study, 20 suspected samples were tested by both techniques that 2 samples were positive and 18 samples were negative in PCR, and 5 samples were positive and 15 samples were negative in pathologic technique .