A case of White Eye Syndrome in cultured whiteleg shrimp (litopenaeus vannamei) in concrete ponds

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Abstract

A month after movement of 1800 pieces of L. vannamei (average weight of 16g) from
culture ponds in Heleh region to concrete ponds of Bandargah hatchery (Bushehr province)
some shrimps showed symptoms such as decrease in growth rate, loss of appetite, dark
pigmentation of cuticle and presence of black foci on it, redness of uropods and white,
irregular and circular spots on the eye with 2-5mm diameters. For detection of etiological
agent samples were taken for PCR, bacteriological and histo-pathological tests. Nested PCR
test using IQ2000 kits for detection of major shrimp viral pathogens (IHHNV, WSSV, YHV
and TSV) were conducted and all results were negative. In histo-pathological tests, lesions in
eyes were liquefactive necrosis of cone cells and cone crystals with infiltration of hemocyte
and formation of micro abscess in the diapteric region of eye. In bacteriological tests, a gram
negative pleomorphic bacterium of the genus Aeromonas was isolated. However, it seems that
this bacterium is the secondary agent and for detection of the primary agent more research is
needed.
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