Outbreak of Edwardsiella tarda in cultured Pangasius hypophthalmus (Sauvage, 1878)
Outbreak of Edwardsiella tarda in cultured Pangasius hypophthalmus (Sauvage, 1878)
Date
2019
Authors
Joseph, T.C.
Dinesh, R.
Shaheer, P.
Murugadas, V.
Rekha, M.
Lalitha, K.V.
Journal Title
Journal ISSN
Volume Title
Publisher
Society of Fisheries Technologists (India), Cochin
Abstract
Mass mortality and morbidity were reported from
cultured Pangasius hypophthalmus (Sauvage, 1878) in
an aquaculture farm in Kerala, India. Pure bacterial
cultures were isolated and identified as Edwardsiella
tarda from body ulcers and internal organs of
moribund P. hypophthalmus and from sediments of
farms without an outbreak. LD50 in P. hypophthalmus
models of the isolates from diseased fish (1.25 X 105
CFU per fish) and isolates from sediment samples
(1.18 X 105 to 3.8 X 105 CFU per fish) were similar.
PCR targeting esaV gene was unable to discriminate
the pathogenic and non-pathogenic E. tarda. However,
ERIC-PCR followed by dendrogram analysis
differentiated isolates based on the presence of
esaV gene. The isolates that did not carry the
esaV gene also were found to be virulent in
P. hypophthalmus fingerlings. Hence it can be assumed
that the type III secretory system along with
other virulence determinants contributes to virulence
by E. tarda in fishes.
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Citation
Fishery Technology 56(2):151-157