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Epidemiology of Viral Hemorrhagic Septicemia among Juvenile Pacific Herring and Pacific Sand Lances in Puget Sound, Washington

Viral hemorrhagic septicemia (VHS) and the associated virus (VHSV)   were identified in newly metamorphosed Pacific herring Clupea   pallasi and Pacific sand lances Ammodytes hexapterus captured from   Puget Sound, Washington, between 1995 and 1998. During that 4-year   period, virus was detected in less than 1% of free-ranging, age-    Pacific herring; however, when groups of these fish were confined in   the laboratory, they experienced severe mortality, occasionally   exceeding 5 %, with the prevalence of VHSV reaching 1  % by 14 days   postcapture. At 7-21 days postcapture, VHSV titers peaked in excess   of 1 8 plaque-forming units/g of tissue; by 3  days postcapture,   however, the virus could no longer be isolated. Fish surviving   beyond 3  days eliminated the virus from their tissues, but some   remained lethargic and continued to show signs of hemorrhage around   the mouth, skin, and fins until about 6 weeks postcapture. No   cutaneous ulcers were observed during either the acute or the   recovery phases of infection. Eighteen-month-old Pacific herring   captured from the same area were also negative for VHSV but   developed active infections after confinement for 7 days. Unlike   younger fish, only 8.4% of these older fish died of VHS, and 7.7% of   survivors were positive for VHSV at 7-1  days postcapture, which   suggests that a higher proportion of the older fish had developed   resistance to VHSV from prior exposure to it.   Three months after fatalities ceased in the laboratory-held fish,   the surviving fish were challenged with 5 × (1 )3 plaque-forming   units/mL of VHSV for 1 hour. No mortality was observed during the   next 3  days, and the virus was recoverable at very low titers in   fewer than 5% of the challenged fish, indicating the development of   an active immunity to VHSV. Laboratory cohabitation of infected wild   Pacific herring with laboratory-reared, specific-pathogen-free   Pacific herring resulted in transmission of VHSV to the nonimmune   fish, with the resulting course of disease resembling that seen in   wild Pacific herring confined in the laboratory. The possible   effects of VHS on stocks of Pacific herring are discussed.    (VHS); (VHSv); (viral hemorrhagic septicemia); (viral haemorrhagic   septicaemia); (viral hemmorrhagic septicemia)

In progress
Start Date
End Date
Scope of Study
Field Investigation
Laboratory Investigation
Scale of Phenomena
Impact of Pollutants
Exotic Species
Resource Management
Resource Being Monitored
Beneficial Use Impairment Assessments
Fish Tumours or Other Deformities
Loss of Fish and Wildlife Habitat
Tainting of Fish and Wildlife Populations
Biology And Life History
Parasites and Diseases
Annex Numbers
Research & Development
Surveillance and Monitoring
Annex 17
Impact of water quality and AIS on fish and wildlife populations and habitats
  • Annex Numbers
    Annex Numbers
    Research & Development
    Surveillance and Monitoring
  • Annex 17
    Annex 17
    Impact of water quality and AIS on fish and wildlife populations and habitats

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