References
http://www.focusonfishhealth.org/
- http://www.dnr.state.mn.us/fish_diseases/vhs.html
- http://www.inspection.gc.ca/english/anima/aqua/virsep/questione.shtml
- http://www.cfsph.iastate.edu/Factsheets/pdfs/viral_hemorrhagic_septicemia.pdf
Surveillance and Detection
http://www.nps.gov/apis/parkmgmt/upload/VHS%20Plan%20-%20Final%202008Mar14.pdf
- http://www.aphis.usda.gov/animal_health/animal_dis_spec/aquaculture/downloads/vhs_surv_plan.pdf
- http://mi.gov/documents/dnr/Viral-Hemorrhagic-Septicemia-Fact-Sheet-11-9-2006_178081_7.pdf
Greatly enhanced surveillance is needed which determines where the pathogen is present and how it works
Brian Noonan, Peter J. Enzmann, Trevor J. Trust. "Recombinant Infectious Hematopoietic Necrosis Virus and Viral Hemorrhagic Septicemia Virus Glycoprotein Epitopes Expressed in Aeromonas salmonicida Induce Protective immunity in Rainbow Trout (Oncorhynchus mykiss)." Applied and Environmental Microbiology 61.10 (1995): 3586-3591.
What is being done
- www. Dnr.state.mn.us/fish_diseases/vhs.html
a. Establish zones for wild fish surveillance
- www.ncbi.nlm.nih.gov/pubmed/15475310
b. Estimate VHSV IVb infection risk.
c. Construct sampling frames
d. Prioritize surveillance effort to higher-risk areas.
e. Conduct veterinary inspections.
- http://www.dec.ny.gov/animals/25328.html
f. Target fish for testing.
g. Submit samples to an approved laboratory
- http://www.vtfishandwildlife.com/vhs.cfm
What is not known
h. Evaluate disease freedom
- There are no treatments at this time to stop horizontal (fish to fish) transmission or to treat infected fish.
- But virus is sensitive to many disinfectants, including formalin, sodium hydroxide, sodium hypochlorite
- Vikron Aquatic disinfectant
- UVC irradiation can treat inflow water for hatcheries or water in recirculation systems
- Vaccines are currently in development for the European isolates of VHSV.
- wide range of potential carriers for the pathogen
- Repeated fish mortalities have not yet been documented in locations that had seen
earlier VHS related fish kills.
- It is not known at this time how smaller inland lakes will respond to VHSv.
- Also do not know whether the virus will skip years and the role of environmental variables such as climate in causing the disease to be expressed is unknown.
- Information is unavailable at this time concerning the ability of disease survivors to maintain an immune response, and whether this response reduces with time, potentially making these fish susceptible to re-infection.
This makes it hard for proper surveillance and detection
Viral Hemorrhagic Septicemia Virus
Improving Practices
- Rigorous biosecurity measures in fish culture facilities and hatcheries
- Information and posted warnings for anglers, boaters, and fish farmers
- Either terminating fish transfers between waters or requiring the mandatory
testing prior to the transfer of wild fish between waters
- Improving the practices of the bait industry and restricting risky uses of
baitfish
- Improving the practices of recreational boaters to limit contamination of waters
- Ensuring the commercial fishing industry does not transfer infected wild fish
into uninfected waters
- Notification of authorities
Control Measures and Prevention
Funding for Research
"It is very unclear what the long-term risk is to our Great Lakes and inland fish stocks from this pathogen as susceptibility and virulence studies are still in
progress on this isolate.
Questions still need answering:
- How long this virus can survive in the environment outside of a fish host?
- Can you detect VHSv in the water prior to fish kills?
- Which species are susceptible to the virus?
- How can we more effectively detect the virus?
Increasing the amount of information available to the public on the pathogen and how to prevent its spread is key!