The host: The majority of fish species can be host of these intracellular bacteria. The specific sample comes from farmed greater amberjack, Seriola dumerili
The disease: The disease is characterized by intracellular inclusions located mostly in the gill epithelium of the affected fish. The inclusions are filled with densely packed bacteria. Although in the past, Chlamydia were considered to be the principal aetiological agents, latest genomic studies have revealed a big variety of bacterial pathogens which can be responsible of the pathology including beta- and gamma-proteobacteria. In acute cases the cyst affect the normal function of the gills resulting in breathing distress and mortalities especially in younger individuals.
Epidemiology: Epitheliocystis is one of the most common diseases. It has been reported in at least 90 fish species worldwide. In aquaculture it usually affects younger fish especially during the first months after their transfer to sea cages.
