Viral hemorrhagic septicemia virus (VHSV), Infectious hematopoietic necrosis virus (IHNV), and infectious pancreatic necrosis virus (IPNV) are documented as the most considerable viral pathogens in Rainbow trout (Onchorhynchus mykiss). This study aimed to evaluate the frequency of these pathogens in 65 farms with suspected clinical signs in northern Iran from March 2016 to February 2018. Logistic regression analysis used to assess the effect of several determinant factors on the occurrence of these pathogens. In total, 19 (29.23%) farms were positive by a reverse transcription-polymerase chain reaction (RT-PCR). The frequency of VHSV, IHNV, and IPNV was reported 18.5%, 6.2%, and 4.61%, respectively. The most affected farms (78.95%) used river water. Furthermore, our results revealed that using river water raised the chances of viral disease by 5 times (OR= 5.02; P= 0.01). Thus, using river water was a risk factor for the occurrence of viral pathogens. From four weight groups (A to D); fishes in groups A (fish < 1 gr) and B (1 to 20 gr) were more affected but not statistically significant (P>0.05). This study has provided insight into the frequency of these targeted viruses. Collectively, establishing routine rapid diagnostic programs and setting up basic educational practices can be valuable to design the prevention and control strategies.

The objectives to this research were to determine the haematological changes in Oryctolagus cuniculus as an animal model in response to killed hemorrhagic septicemia virus (VHSV) virulent to Oncorhynchus mykiss. This study composed of 5 groups; Treatment 1 (T1) with 1cc virus, treatment 2 (T2) with 0.5cc virus and 0.5cc adjuvant, treatment 3 (T3) with 0.75cc virus and 0.25cc adjuvant, treatment 4 (T4) with 0.25cc virus and 0.75cc adjuvant, and a control for a period of 4 months, once a month IM injection in 5 group of three New Zealand rabbits with health certification prepared by Razi Vaccine and Serum Research Institute. After 15 days, blood parameters, hematocrit (HCT), hemoglobin (HGB), mean hemoglobin concentration in red blood cells (MCH), red blood cells (RBC), average concentration of red blood cell (MCHC), white blood cells (WBC), neutrophils (SEG), lymphocytes (Lyn), eosinophil (Eos), aspirate transaminase (AST) and alanine transaminase (ALT).The results  showed that ALT, AST, HCT, HGB and WBC concentrations of all rabbits significantly were difference (p < 0.05). T2 (0.5cc virus and 0.5cc adjuvant) and T3 (0.75cc virus and 0.25cc adjuvant) showed higher ALT, AST, HCT and WBCs among other treatments in all 4 blood samplings and among these treatments, T2 with lower levels of ALT and AST (indicating less pressure on the liver) and higher levels of WBCs which can lead to greater amount of neutralizing polyclonal antibodies indicated better results.