Rock bream iridovirus (RBIV) infection - a health problem in aquacultures

Aquaculture contributes significantly to meeting the increasing demand for aquatic foods such as finfish, shellfish. and algae. According to a report by the Food and Agriculture Organization (FAO) of the United Nations in the 2024 edition of The State of World Fisheries and Aquaculture (SOFIA), aquaculture production of aquatic animals has now surpassed capture fisheries for the first time (1).

Rock bream (Oplegnathus fasciatus) is an important species for fish farming in East Asia. However, outbreaks of the rock bream iridovirus (RBIV) constitute a health risk to the aquacultures. Infections can stem from environmental factors, co-infection with other pathogenic microorganisms, or from ground (raw) fish feed (2).

View of a a fish farm

Similarities and differences between infection routes

Korean researchers recently published a study of RBIV infection in rock bream (3). Using the Exigo H400 veterinary hematology system and blood smear analysis, differences and similarities in hematological indicators between intraperitoneal and oral infection routes were investigated. Exigo C200 veterinary chemistry system was used to analyze levels of aspartate aminotransferase (AST/GOT), alanine aminotransferase (ALT/GPT), alkaline phosphatase (ALP), glucose (GLU), total cholesterol (TC), and triglyceride (TG).

The researchers observed both similarities and differences in the distribution of white and red blood cells between intraperitoneal and oral infection routes. In both the oral and intraperitoneal infection routes, an increase in leukocytes occurred rapidly at all infection times, indicating a response to the RBIV infection in rock bream. In the intraperitoneal infection route, the levels of RBC, HGB, HCT, and MCH decreased in late stage of infection, while in the oral infection route, RBC, HGB, and HCT levels were normal at all stages of infection. RDW, on the other hand, was found to be abnormal at all stages of infection in both the oral and intraperitoneal infection routes. The results indicate that the oxygen supply was affected by RBIV infection.

Exigo H400 and Exigo C200 was used in the study of RBIV infection in rock bream

Learn more

A complete blood count, together with a chemistry analysis, is frequently requested by veterinarians to determine the health and physiological status of an organism. Learn more about the Exigo H400 hematology system and Exigo C200 chemistry system, their use in veterinary application, and The power of combination.

References

1. FAO Report: Global fisheries and aquaculture production reaches a new record high in The State of World Fisheries and Aquaculture 2024 (fao.org, accessed 2024-12-16).
2. Kim et al. Effect of feeding rock bream iridovirus (RBIV)-containing tissues on mortality rates in rock bream (Oplegnathus fasciatus). Fish Shellfish Immunol 153, 109858 Epub (2024).
3. Jung et al. Oral route of transmission for rock bream iridovirus (RBIV) infection in rock bream (Oplegnathus fasciatus): clinical signs and hematological indicator changes. Epub https://doi.org/10.2139/ssrn.4866289 (2024).