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thumbnail for publication: Lymphocystis Disease in Fish

Lymphocystis Disease in Fish

Roy P. E. Yanong

Lymphocystis is a chronic disease of freshwater and marine fishes caused by infection with an iridovirus known as Lymphocystivirus or Lymphocystis disease virus (LCDV), which is a member of the family Iridoviridae. Infection results in the development of pebble or wart-like nodules most commonly seen on the fins, skin, or gills, although other tissues may be affected. Although the disease has been seen worldwide in numerous species since its first description in 1874, its viral cause was not identified until 1962. The lymphocystiviruses are considered much less pathogenic (disease-causing) than their iridoviral relatives, the ranaviruses and megalocytiviruses, which can cause severe, systemic disease with higher mortalities.

thumbnail for publication: Viral Nervous Necrosis (Betanodavirus) Infections in Fish

Viral Nervous Necrosis (Betanodavirus) Infections in Fish

Roy P. E. Yanong

This document is about betanodaviruses, an emerging group of viruses infecting over 40 marine and some freshwater fish species worldwide1. It details the characteristics of these viruses, including their non-enveloped, icosahedral-shaped capsid and single-stranded, positive-sense RNA2. The document discusses the diseases caused by betanodaviruses, such as viral nervous necrosis (VNN) and viral encephalopathy and retinopathy (VER), which primarily affect the central nervous system of fish34. It also covers prevention and control measures, including good husbandry, biosecurity, and the potential use of vaccines. The document emphasizes the importance of working with fish health professionals for diagnosis and management. First published Dec. 2010.