Philasterides dicentrarchi, a histophagous ciliate causing scuticociliatosis in olive flounder, Philasterides dicentrarchi--histopathology investigations.
Philasterides dicentrarchi is a histophagous scuticociliate infecting Korean olive flounder farms in Jeju Island, South Korea, where it causes significant economic losses. However, the route of entry of these parasites in olive flounder is currently unknown. In the present study, we attempted experimental infection with different doses (concentrations) of P. dicentrarchi by intraperitoneal (IP) injection; maximum cumulative mortality of 95% was recorded on the administration of 2.1×10(8) ciliates/ml. In small size group (3 cm length, 24±2 gwt) the ciliates were found in connective tissues of muscle, fins, and nervous tissue while in large size group (5 cm length, 47±3 gwt), the ciliates were predominantly occurred with associated symptoms of liquefaction in the central nervous system. The major clinico-pathological manifestations were loss of scales, appearance of bleached spots that coalesced to form brownish patches, hemorrhagic, and severe dermal necrotic lesion. In addition there was degeneration of muscle fibers, necrosis of the hepatic parenchyma, and severe edema of the intestinal walls, extensive fouling, necrotic degeneration and hyperplasia in the gill bronchial epithelium. In this study, many ciliates were found in the blood vessel, brain, dorsal fins, muscle, kidney, and vertebra of infected flounder. The histopathological investigations are of significant importance in view of possible routes of entry into the host and doses of ciliates that trigger fast infection for potential utility of drugs as a strategy for the control of P. dicentrarchi in farmed olive flounder.
Marine Applied Microbes and Aquatic Organism Disease Control Lab, Department of Marine Life Sciences, School of Marine Biomedical Sciences, College of Ocean Science, Jeju National University, Jeju 690 756, South Korea. rhari123@yahoo.com
Ramasamy
R
Harikrishnan
Chang-Nam
CN
Jin
Ju-Sang
JS
Kim
Chellam
C
Balasundaram
Moon-Soo
MS
Heo
D058500:Animal Fins / Q000469:parasitology / Q000473:pathology; D000818:Animals; D001921:Brain / Q000469:parasitology / Q000473:pathology; D016798:Ciliophora / Q000145:classification / Q000302:isolation & purification / Q000502:physiology*; D016770:Ciliophora Infections / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D005393:Fish Diseases / Q000469:parasitology* / Q000473:pathology; D005398:Fisheries; D005432:Flounder / Q000469:parasitology*; D007568:Jaw / Q000469:parasitology / Q000473:pathology; D007668:Kidney / Q000469:parasitology / Q000473:pathology; D018482:Muscle, Skeletal / Q000469:parasitology / Q000473:pathology; D013131:Spine / Q000469:parasitology / Q000473:pathology