Cultured juvenile striped trumpeter, Latris lineata (Forster), were sampled at two time points in spring (68 fish)
and autumn (48 fish) to assess the prevalence and severity of epitheliocystis and associated physiological impacts.
Prevalence of epitheliocystis was 49.2% in spring and 100% in autumn. Fish sampled in spring had low
mean density of epitheliocystis induced cysts at 0.39±0.08 per cm2 whereas those fish sampled in autumn
had significantly higher mean cyst density at 134.93±15.81 (pb0.05). Themean diameter of cysts did not differ
and itwas 47.9±3.41 μmin spring and 50.7±0.50 μmin autumn. The cystswere positioned at the tips or along
lamellae. Host response was affected by the severity of infection. Histological examination revealed little host
response in striped trumpeter with low densities of cysts; however proliferative responses, including lamellar
fusion due to epithelial hyperplasia and inflammation, were present in fish that had higher cyst densities.
Serum osmolality and lysozyme activity were positively correlated with the densities of cysts in juvenile striped
trumpeter (pb0.001). Furthermore, the osmolality and lysozyme activity of infected striped trumpeterwere significantly
elevated compared with the non-infected striped trumpeter (pb0.05). Histological examination revealed
the absence of chloride cells at the base of the gill lamellae in the vicinity of the cysts, which may
explain the elevation of osmolality in the individuals affected by epitheliocystis. However, the counts of chloride
cells in the interlamellar areas did not differ between the fish with high and normal osmolality (p>0.05). This
study describes the first case of epitheliocystis in striped trumpeter and reports associated physiological effects.