The occurrence of "White Eye Syndrome" in cultured white leg shrimp (Litopenaeus vannamei) in Iran

Objective: Eye lesions observed in cultured white leg shrimp after their movement from culture pond to a greenhouse of hatchary in Boushehr Province. We studied their clinical symptoms, histopatological changes and aetiological agent(s). Method & Materials: we examined shrimps weekly for observation of any clinical signs and then samples were collected for histopathology in Davidsons fixative, live samples for microbiology and pleopods and gills in ethanol 95% for PCR. Results & Conclusion: Shrimps displayed a variety of non-specific signs of disease, including lethargy, anorexia, growth reduction, dark pigmentation, empty of midgut, white muscle, necrosis of uropods and fouled cuticle and death. Morbidity estimated near 70% and mortality near 10% .In pond- side examination, the lesions of eye appeared as a circular to slightly irregular white spots with 2-5 diameter. In histopathological study, affected eyes showed supperative inflammation, liquefactive necrosis and granuloma in diaptoric portion of ommatidia and all associated structure that characterized by edema, infiltration of haemocytes, local abscesses and replacement of fibrous tissue. In PCR tests for detection of WSSV,YHV,IHHNV,TSV by IQ2000 kits on 36 samples of pleopode and gills, all results were negative but bacteriological culture from lesions showed Gram-negative rods bacteria and further chemical tests showed that isolated bacteria were near to Vibrionacea and genus Aeromonas. For treatment of disease, oxytetracycline (70 mg/kg) was used but no good response obtained however it seems that this syndrome due to unknown primary agent and Aeromans cause secondary infection. More information need to clear primary agent.

کلیدواژه ها:

white leg shrimp ، eye ، white spot