Fish can get mad cow disease says study
Picture by David Blaikie, Creative Commons.
Greek scientists have discovered that it is possible for fishes to contract mad cow disease.Evgenia Salta and coauthors published the results of their studies on the transmissibility of bovine spongiform encephalopathy (BSE or mad cow disease) and scrapie (another transmissible spongiform encephalopathy, TSE) in the gilthead sea bream (Sparus aurata, a species widely farmed for food) in a recent issue of the journal PLoS ONE.
The authors divided 1600 sea bream into groups of 200 and force-fed each group with a variety of infected, and non-infected brain homogenates, ranging from scrapie-infected sheep, healthy control sheep, BSE-infected cow and healthy control cow.
The force-feeding procedure was repeated fortnightly for a total of five treatments.
Following the inoculation period, all fish were kept on a maintenance diet with commercially feed to prevent excessive growth and overcrowding during the multiyear study period.
The authors observed the fishes for any signs of abnormalities in behaviour or in swimming, and regularly examined sacrificed individuals (at 3, 6, 8, 10, 12, 14, 16, 18, 24 months) to examine the histology of organs such as the brain, spleen and intestine.
Finally, the authors confirmed the presence of the appropriate prion proteins (PrP) – the agents responsible for spongiform encephelopathies – using immunohistological methods.
The authors found that while the bream never displayed clinical signs of spongiform encephelopathies during the study period, the brains of TSE-fed fish sampled two years after challenge showed signs of neurodegeneration and accumulation of deposits that reacted positively with antibodies raised against sea bream PrP. The control groups, fed with brains from uninfected animals, showed no such signs.
While the authors acknowledge that more studies are needed to study infectivity and transmission of TSEs in fish, the prospect of farmed fish being contaminated with infectious mammalian PrP, or of a prion disease developing in farmed fish is an alarming one.
They conclude that “...the possibility that the affected sea bream brain tissue might be infectious, must be taken seriously in any consideration to lift EU feed bans, especially those related to farmed fish.”
For more information, see the paper: Salta E, C Panagiotidis, K Teliousis, S Petrakis, E Eleftheriadis, F Arapoglou, N Grigoriadis, A Nicolaou, E Kaldrymidou, G Krey and T Sklaviadis (2009) Evaluation of the possible transmission of BSE and scrapie to gilthead sea bream (Sparus aurata). PLoS ONE 4(7): e6175. doi:10.1371/journal.pone.0006175
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Heok Hee Ng: 15.9.2009More: PLoS One
Views: Read 4,523 times
Comments feed
"why was this done?
do farmed fish normaly feed a mixture of animal bi-products? i know that animals are but fish?
if they are then i can understand the reason it was done, but if not this seems like an awful waste of time not to mention the side effects that this experiment has had on the fish & not just the infected ones. next they will be testing to see if the fish shops excess supply of guppys can be used for fish fingers."
Date: Thursday September 17th, 2009, 12:33 am
"Prions, the infectious cause of mad cow, can enter the water table from slaughterhouses, improper disposal of infected and culled livestock, landfills, improperly cleaned wild game (deer can also be carriers) or from the excrement of human carriers.
these prions can survive waste-water treatment, so they end up in fertilizers, water supplies for fish farms and downstream to wild populations.
"
Date: Wednesday October 7th, 2009, 4:54 pm
"Those guys work for the Fisheries Research Institute of Greece,,,
OF COURSE the experiment is important, OF COURSE there is reason to know if such diseases can be passed on to aquacultured fish.
Being aquarists doesn't mean that we live in a parallel universe...
Fish are also aquacultured for human consumption, you know, and such knowledge is very important!"
Date: Wednesday October 7th, 2009, 6:03 pm
"We have all seen how disastrous the processing of diseased animals as feed for other animals has proven in the past.
This experiment was obviously conducted to prove the hypothesis that the same thing would happen to farmed fish fed the same way.
Given past experience, I would have thought it a given ... but the results are in ... I hope no-one has been feeding the Sea Bream their dead cows in the meantime.
"
Date: Thursday October 8th, 2009, 1:53 am
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 | Singapore-based ichthyologist Dr Heok Hee Ng is a leading expert on Asian catfishes and has described dozens of fish ranging from catfishes, to nandids and cyprinids. |
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"Its a bit of a macabre experiment isn't it! i wonder if they were expecting this outcome? seems a bit of a strange experiment just to do because its interesting... "
Posted by: Jordan Rich - 2 months agoDate: Tuesday September 15th, 2009, 12:45 pm