Investigation of Outbreaks of Viral Hemorrhagic Septicemia and Associated Risk Factors in Rainbow Trout Farms in Iran, 2014

Abstract

Background and Objectives: In Iran, rainbow trout farms exist in almost all provinces. Viral hemorrhagic septicemia is one of the most important infectious diseases of the rainbow trout which is a serious threat to the farming industry. This study was conducted to investigate outbreaks in 2014 and identify important determinants of the agent entry and disease occurrence in the farms. Methods: Data were collected using a structured questionnaire and the disease was detected based on clinical signs and laboratory investigations by PCR methods. Results: During 52 weeks of the study in 2014, 114 of 1140 (12.63%) farms were affected within 78 zones in 14 provinces. In multivariable analysis, illegal entrance of fries (odds ratio: 7.81, 95% CI: 3.63-16.8), illegal entrance of fish (odds ratio: 5.60, 95% CI: 3.03-10.35) and use of river as the water supply (odds ratio: 2.46, 95% CI: 1.51-4.02) were detected as risk factors associated with virus entry and disease outbreak in farms. Conclusion: Observing biosecurity measures in the farm level, applying risk-based surveillance based on known risk factors, and assessing these factors on a regular basis are important in prevention and control of VHS.

Keywords

• viral hemorrhagic septicemia (vhs)
• risk factors
• rainbow trout farms