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ID 25656
file
creator
Sugumar, G.
Hirata, Yasushi
Matsubara, D.
Muroga, Kiyokuni
subject
Bacillary necrosis
Vibriosis
Crassostrea gigas
Larvae
Vibrio splendidus II
Pathogenicity
NDC
Zoology
abstract
Recurrent outbreaks of a disease leading to mass mortalities in an oyster (Crassostrea gigas) hatchery located in western Japan were investigated. The disease occurred regularly in 2- to 8-d-old larvae and has been experimentally controlled in the hatchery by treating the larval rearing water with streptomycin, without ascertaining the etiological agent. The signs of the disease and the course of infection resembled bacillary necrosis reported in oysters and other bivalve molluscs in the USA and Europe. Quantitative and qualitative examinations of the bacterial flora of hatchery samples including source water, broodstock, larval feed and larvae revealed a very high total bacterial load and presumptive vibrios in diseased larvae. Further, the bacterial profile revealed that Vibrio spp. constituted approximately 60 to 95% of the bacteria isolated from infected larvae and most isolates were identified as V. splendidus biovar II and V. harveyi, suggesting their possible role in the disease. However, experimental challenges proved the pathogenicity of V. splendidus II. Several isolates of V. splendidus II from infected larvae were highly pathogenic, producing 100% mortality at levels of 105 cfu ml-1 in 24 h, while isolates from other sources demonstrated a low degree of virulence. Detection of V. splendidus II from broodstock, especially in the gonad of a few breeders, suggests the probability that broodstock could be the source and route of transmission of this pathogen.
journal title
Diseases of Aquatic Organisms
volume
Volume 33
issue
Issue 2
start page
111
end page
118
date of issued
1998-06-19
publisher
Inter-Research
issn
0177-5103
1616-1580
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 1998 Inter-Research.
relation url
department
Graduate School of Biosphere Science