Amyloodiniosis

Antiparasitic approaches and strategies in European aquaculture, with emphasis on Mediterranean marine finfish farming: Present scenarios and future visions

“…The development of parasitic diseases is strongly related to the parasite's life cycle, the rearing system, and the environmental conditions of the farming type. Infections caused by parasites with short life cycles such as ciliates and flagellate protozoans can be favoured in enclosed aquaculture systems, 56 with limited water exchange such as tanks operating in flow‐through or RAS systems, or ponds and lagoons that facilitate the fast multiplication of several forms of the parasite cycle 57,58 . In contrast, fish reared in cages are particularly prone to parasitic diseases with a long‐term cycle, 59 where one or several forms of the fish parasite cycle are permanently present or attached to the environment of the cages and their surroundings 60,61 .…”

Amyloodiniosis in aquaculture: A review

“…29,78,79 Amongst them, the ones that have a more important role in the modulation of A. ocellatum pathogenicity and life cycle are temperature and salinity. 147 A. ocellatum can reproduce at temperatures between 16 and 30 C, with more effective tomite production at 23-27 C, total inhibition of tomont division, and gradual mortalities of the parasite at 8 C and delayed or interrupted division of the tomont at 35 C, making temperature one of the key environmental conditions for tomont division and eclosion. 123 Salinity is another environmental factor to be considered as A. ocellatum can tolerate salinities between 10 and 60 psu, with an optimum salinity range between 18 and 39 psu for the optimal temperature range described for tomont eclosion.…”

“…147 With the outbreak progression and increase in the infestive load (more than 100-200 trophonts per primary lamellae), a severe and diffuse epithelial hyperplasia, with epithelium degeneration, characterised by hydropic degeneration of gill epithelia and ionocytes (chloride cells) that can lead to necrosis and edema can be observed in the oropharyngeal cavity. 147 In the gill, it is described by various authors that A. ocellatum severe infestation causes several lesions and hyperplasia of the respiratory epithelium, accompanied by lamellar fusion, detachment of the epithelium, venous sinus dilatation, aneurysm formation and rupture of the lamellar epithelium, decrease in mucous cell abundance, haemorrhages, necrosis and lymphocytic inflammatory reaction (Figure 5). 22,65,120,147 Regarding the type of lesions observed in different affected fish species, a compilation of the lesions in the gills described in the literature is presented in Table 2.…”

“…Regarding the outbreak conditions for amyloodiniosis, several environmental conditions are documented in the literature 29,78,79 . Amongst them, the ones that have a more important role in the modulation of A. ocellatum pathogenicity and life cycle are temperature and salinity 147 . A. ocellatum can reproduce at temperatures between 16 and 30°C, with more effective tomite production at 23–27°C, total inhibition of tomont division, and gradual mortalities of the parasite at 8°C and delayed or interrupted division of the tomont at 35°C, making temperature one of the key environmental conditions for tomont division and eclosion 123 .…”

“…On the onset of this disease and in very mild infestations (no more than 10 trophonts per primary lamella), no significant lesions are observed. However, inflammatory cells can be detected around the single trophont adhesion site 147 . With the outbreak progression and increase in the infestive load (more than 100–200 trophonts per primary lamellae), a severe and diffuse epithelial hyperplasia, with epithelium degeneration, characterised by hydropic degeneration of gill epithelia and ionocytes (chloride cells) that can lead to necrosis and edema can be observed in the oropharyngeal cavity 147 .…”