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Modelling Infectious Hematopoietic Necrosis Virus Dispersion from Marine Salmon Farms in the Discovery Islands, British Columbia, Canada.

Foreman MG, Guo M, Garver KA, Stucchi D, Chandler P, Wan D, Morrison J, Tuele D - PLoS ONE (2015)

Bottom Line: Numerical particles released from infected farm fish in accordance with IHNV shedding rates estimated through laboratory experiments are dispersed by model oceanic flows.Results demonstrate that neighbouring naïve farms can become exposed to IHNV via water-borne transport from an IHNV diseased farm, with a higher risk in April than July, and that many events in the sequence of farm outbreaks in 2001-2002 are consistent with higher risks in our farm connectivity matrix.Applications to other diseases, transfers between farmed and wild fish, and the effect of vaccinations are also discussed.

View Article: PubMed Central - PubMed

Affiliation: Institute of Ocean Sciences, Fisheries and Oceans Canada, P.O. Box 6000, Sidney, B.C., V8L 4B2, Canada.

ABSTRACT
Finite volume ocean circulation and particle tracking models are used to simulate water-borne transmission of infectious hematopoietic necrosis virus (IHNV) among Atlantic salmon (Salmo salar) farms in the Discovery Islands region of British Columbia, Canada. Historical simulations for April and July 2010 are carried out to demonstrate the seasonal impact of river discharge, wind, ultra-violet (UV) radiation, and heat flux conditions on near-surface currents, viral dispersion and survival. Numerical particles released from infected farm fish in accordance with IHNV shedding rates estimated through laboratory experiments are dispersed by model oceanic flows. Viral particles are inactivated by ambient UV radiation levels and by the natural microbial community at rates derived through laboratory studies. Viral concentration maps showing temporal and spatial changes are produced and combined with lab-determined minimum infectious dosages to estimate the infective connectivity among farms. Results demonstrate that neighbouring naïve farms can become exposed to IHNV via water-borne transport from an IHNV diseased farm, with a higher risk in April than July, and that many events in the sequence of farm outbreaks in 2001-2002 are consistent with higher risks in our farm connectivity matrix. Applications to other diseases, transfers between farmed and wild fish, and the effect of vaccinations are also discussed.

No MeSH data available.


Related in: MedlinePlus

Average virus concentrations (log10 (pfu m-3)) over the top twenty meters of the water column on April 15, 2010 arising from releases of 1.6 × 1011 pfu/hour at five farms around Nodales Channel.Black circles denote the release (diseased) farm (numbered as in Fig 1) while white circles show locations of the other four.
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pone.0130951.g003: Average virus concentrations (log10 (pfu m-3)) over the top twenty meters of the water column on April 15, 2010 arising from releases of 1.6 × 1011 pfu/hour at five farms around Nodales Channel.Black circles denote the release (diseased) farm (numbered as in Fig 1) while white circles show locations of the other four.

Mentions: As an example of the output from these particle tracking studies, Figs 3 and 4 show daily average virus concentrations (pfu m-3) over the top 20m of the water column for April 15 and July 15, respectively. (The concentrations were computed by summing the proportion of active cohorts in volumes of size 100m by 100m by 20m covering the model domain.) Only releases from five farms around Nodales Channel (Fig 1) are considered and they have been scaled-up to represent a shedding rate of 1.6 × 1011 pfu/hour/farm. Though not shown, it should be noted that these concentrations do vary over a twenty-four hour period as the exposure to UV radiation varies. Specifically, concentrations in the evening after exposure to UV radiation over the preceding daylight hours are smaller than those around sunrise that have gone without exposure the preceding night.


Modelling Infectious Hematopoietic Necrosis Virus Dispersion from Marine Salmon Farms in the Discovery Islands, British Columbia, Canada.

Foreman MG, Guo M, Garver KA, Stucchi D, Chandler P, Wan D, Morrison J, Tuele D - PLoS ONE (2015)

Average virus concentrations (log10 (pfu m-3)) over the top twenty meters of the water column on April 15, 2010 arising from releases of 1.6 × 1011 pfu/hour at five farms around Nodales Channel.Black circles denote the release (diseased) farm (numbered as in Fig 1) while white circles show locations of the other four.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482787&req=5

pone.0130951.g003: Average virus concentrations (log10 (pfu m-3)) over the top twenty meters of the water column on April 15, 2010 arising from releases of 1.6 × 1011 pfu/hour at five farms around Nodales Channel.Black circles denote the release (diseased) farm (numbered as in Fig 1) while white circles show locations of the other four.
Mentions: As an example of the output from these particle tracking studies, Figs 3 and 4 show daily average virus concentrations (pfu m-3) over the top 20m of the water column for April 15 and July 15, respectively. (The concentrations were computed by summing the proportion of active cohorts in volumes of size 100m by 100m by 20m covering the model domain.) Only releases from five farms around Nodales Channel (Fig 1) are considered and they have been scaled-up to represent a shedding rate of 1.6 × 1011 pfu/hour/farm. Though not shown, it should be noted that these concentrations do vary over a twenty-four hour period as the exposure to UV radiation varies. Specifically, concentrations in the evening after exposure to UV radiation over the preceding daylight hours are smaller than those around sunrise that have gone without exposure the preceding night.

Bottom Line: Numerical particles released from infected farm fish in accordance with IHNV shedding rates estimated through laboratory experiments are dispersed by model oceanic flows.Results demonstrate that neighbouring naïve farms can become exposed to IHNV via water-borne transport from an IHNV diseased farm, with a higher risk in April than July, and that many events in the sequence of farm outbreaks in 2001-2002 are consistent with higher risks in our farm connectivity matrix.Applications to other diseases, transfers between farmed and wild fish, and the effect of vaccinations are also discussed.

View Article: PubMed Central - PubMed

Affiliation: Institute of Ocean Sciences, Fisheries and Oceans Canada, P.O. Box 6000, Sidney, B.C., V8L 4B2, Canada.

ABSTRACT
Finite volume ocean circulation and particle tracking models are used to simulate water-borne transmission of infectious hematopoietic necrosis virus (IHNV) among Atlantic salmon (Salmo salar) farms in the Discovery Islands region of British Columbia, Canada. Historical simulations for April and July 2010 are carried out to demonstrate the seasonal impact of river discharge, wind, ultra-violet (UV) radiation, and heat flux conditions on near-surface currents, viral dispersion and survival. Numerical particles released from infected farm fish in accordance with IHNV shedding rates estimated through laboratory experiments are dispersed by model oceanic flows. Viral particles are inactivated by ambient UV radiation levels and by the natural microbial community at rates derived through laboratory studies. Viral concentration maps showing temporal and spatial changes are produced and combined with lab-determined minimum infectious dosages to estimate the infective connectivity among farms. Results demonstrate that neighbouring naïve farms can become exposed to IHNV via water-borne transport from an IHNV diseased farm, with a higher risk in April than July, and that many events in the sequence of farm outbreaks in 2001-2002 are consistent with higher risks in our farm connectivity matrix. Applications to other diseases, transfers between farmed and wild fish, and the effect of vaccinations are also discussed.

No MeSH data available.


Related in: MedlinePlus