Case Report: Viral Infectious Pancreatic Necrosis in Farmed Rainbow Trout from Mexico

Area of Science:

• Aquatic animal pathology
• Virology
• Fish disease diagnostics

Background:

• Infectious pancreatic necrosis (IPN) is a significant disease affecting farmed fish globally.
• Rainbow trout (Oncorhynchus mykiss) aquaculture is economically important in Mexico.
• Previous reports of IPN in this region were lacking.

Purpose of the Study:

• To provide pathologic and diagnostic documentation of the first clinical epizootic of IPN in farmed rainbow trout in central Mexico.
• To identify and characterize the causative agent of the observed disease outbreak.

Main Methods:

• Gross and microscopic pathologic examination of affected fish.
• Virus isolation in cell culture.
• Identification of the isolated virus using indirect fluorescent antibody test (IFAT) and reverse transcription-polymerase chain reaction (RT-PCR).
• Genotyping of the infectious pancreatic necrosis virus (IPNV) isolate.

Main Results:

• Pathologic findings consistent with IPN were observed.
• A virus exhibiting cytopathic effects typical of IPNV was isolated.
• The isolate was confirmed as IPNV using IFAT and RT-PCR.
• Genotyping identified the isolate as the Buhl strain, belonging to the West Buxton (A1) serotype of aquatic birnavirus serogroup A.

Conclusions:

• This report confirms the first clinical epizootic of IPN in farmed rainbow trout in central Mexico.
• The causative agent was identified as the Buhl strain of IPNV (A1 serotype).
• This finding has implications for fish health management and disease surveillance in Mexican aquaculture.