Viral Hemorrhagic Septicemia

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Viral Hemorrhagic Septicemia

• An acute to chronic, highly contagious viral
  disease of fish which is expanding its range and
  the species it infects
• The Ebola virus of fish
• -
  Anonymous

2
A BRIEF HISTORY OF VHS

• First reported in rainbow trout in Germany in
  1938
• Called Egtved disease in cultured rainbow trout
  in Denmark (1949-50)
• Primarily an enzootic viral disease in rainbow
  trout and turbot in Europe, Sweden and Finland
  (Types I-III)
• Virus brought to US for experimental purposes

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A BRIEF HISTORY OF VHS(CONTINUED)

• Isolated in Pacific herring and pilchard along
  the Pacific Coast of North America (Type IVa)
• Recently appeared in the Great Lakes Basin (Type
  IVb) affects many more species than other types
  of the virus (2003-2006) Found in Lake St.
  Clair, Lake Ontario, Lake Erie, the St. Lawrence
  River, and Lake Conesus
• Identified near Lake Winnebago, Wisconsin, Lake
  Michigan, Lake Huron and Budd Lake (2007)
• At least 42 species affected

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SPECIES AFFECTED TO DATE

• Atlantic cod
• Black crappie
• Bluegill
• Bluntnose minnow
• Brown bullhead
• Brown trout
• Brook trout
• Burbot
• Channel catfish
• Chinook salmon
• Coho salmon
• Chum salmon
• Emerald shiner
• Freshwater drum
• Gizzard shad
• Grayling
• Haddock
• Herring
• Japanese flounder

• Pacific cod
• Pike
• Pink salmon
• Pumpkinseed
• Rainbow trout
• Redhorse sucker
• Rock bass
• Rockling
• Round goby
• Silver and shorthead redhorse
• Smallmouth bass
• Sprat
• Stickleback
• Striped bass
• Turbot
• Walleye
• White bass
• White perch
• Whitefish

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CAUSE OF VIRAL HEMORRHAGIC SEPTICEMIA

• Rhabdovirus (bullet-shaped)
• VHS is NOT a human pathogen
• The VHS virus is a reportable animal disease
• There is no current treatment for the virus

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Viral hemorrhagic septicemia virus
VHS viral particles on fish epithelium. Scanning
electron microscope at 48,000 X
magnification. From Kunkel, Dennis. 2005.
Microscopy Science and Photography through a
Microscope. http//www.denniskunkel.com/.
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HOW IS THE VHS VIRUS SPREAD?
Wildlife
Effluent (virus can last several weeks)
Ballast water
Fomites
Fish offal
Live fish
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OTHER POTENTIAL VECTORS

• Has been found in Zebra Mussels, an invasive
  aquatic species
• Has been found in the regurgitated contents from
  birds
• Other invertebrates could potentially carry the
  virus
• Unknown if they can spread infective forms of the
  disease (may be dose- dependent)
• ??? Frozen baitfish ???

Bottom photo courtesy of Pete Walker
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HOW LONG DOES THE VIRUS LAST IN WATER?

• Depends on water temperature and whether it is
  fresh or sea water
• Type IVb (yellow) lasted up to 49 days in
  unfiltered freshwater (Kyle Garver)

Unfiltered fresh water
Unfiltered sea water
pfu plaque forming units
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TRANSMISSION OF VHS

• FISH TO FISH
• Urine, feces, sexual fluids
• POSSIBLE VERTICAL TRANSMISSION
• Appears to be a surface contaminant
• ENTRY TO FISH
• Thought to gain entry via secondary gill lamellae

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OTHER INFORMATION

• Transmissible to all ages of fish
• Survivors can become life-long carriers that shed
  virus
• Mortality occurs at 37-50 F (seen in Spring)
• At temperatures gt59F death rarely occurs

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CLINICAL SIGNS OF VHS
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SKIN HEMORRHAGES
Photos Garth Traxler (USGS, Seattle WA), Dr Jim
Winton (USGS, Seattle WA), Dr Mohamed
Faisal (MSU, Lansing MI) and Dr Paul Bowser
(Cornell, Ithaca NY)
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HEMORRHAGES OF INTERNAL ORGANS
Photos Garth Traxler (USGS, Seattle WA), Dr Jim
Winton (USGS, Seattle WA), Dr Mohamed Faisal
(MSU, Lansing MI) and Dr Paul Bowser (Cornell,
Ithaca NY)
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EXOPHTHALMIA ASCITES
Photos Garth Traxler (USGS, Seattle WA), Dr Jim
Winton (USGS, Seattle WA), Dr Mohamed Faisal
(MSU, Lansing MI) and Dr Paul Bowser (Cornell,
Ithaca NY)
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HEMORRHAGES HEMORRHAGES IN MUSCLE
IN SWIM BLADDER
Photos Garth Traxler (USGS, Seattle WA), Dr Jim
Winton (USGS, Seattle WA), Dr Mohamed Faisal
(MSU, Lansing MI) and Dr Paul Bowser (Cornell,
Ithaca NY)
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FISH KILLS
Makah Tribal Salmon Hatchery, Washington 1988
(Coho salmon)
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DIAGNOSING VHS IN THE LAB
FRESH KIDNEY AND SPLEEN TAKEN FROM FISH
GROWN AT SPECIFIC TEMPERATURES ON APPROPRIATE
CELL LINES TO LOOK FOR CYTOPATHIC EFFECTS
CONFIRMED BY SEROLIGICAL TESTS AND PCR
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What is being done nationally to prevent spread
of VHS

• October 24, 2006 Federal Order issued
  preventing interstate transport 37 species of
  LIVE fish from the 8 states and 2 Canadian
  provinces surrounding Great Lakes
• November 14, 2007, amended the order allowed
  importation or interstate travel of
  VHS-susceptible live fish under certain
  conditions relaxed the laws somewhat to
  decrease hardship on the aquaculture industry of
  those states and provinces.
• May 4, 2007 allowed catch and release
  activities
• Only applies to live fish (fertilized eggs,
  gametes, dead fish, organs, blood, scales not
  covered)
• Future issuance of a proposed USDA/APHIS ruling
  or amendment - currently there is no national
  fish regulation in place to regulate interstate
  fish movements

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WHAT IS THE FUTURE OF VHS?
WHAT IS THE FUTURE OF VHS IN UNITED STATES AND
COLORADO?
? VIRULENT VIRUS CAPABLE OF INFECTING MANY
SPECIES UNDER A WIDE RANGE OF CONDITIONS
? OBVIOUSLY A POTENTIALLY DANGEROUS VIRUS
? VIGILANCE IS NECESSARY
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• Slide show developed by
• Carolyn Gunn, DVM
• Aquatic Animal Health Lab
• Colorado Division of Wildlife
• Brush, Colorado

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What is being done in Colorado?

• Continued inspections of salmonids
• Monitoring other fish species
• Article VII, 014, C1a gives the state authority
  to stop importation of prohibited disease agents,
  including VHSv.
• Review and amendment of current aquatic species
  importation and transportation rules (Fish Health
  Board and Wildlife Commission)
• Looking at importations on a case-by-case basis

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What happens if this disease gets into a fish
production facility?

• Report to CDA, USDA-APHIS, OIE and Director
• Destruction, quarantine, disinfection
• Complete disinfection of facility