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3-D scans map widespread fish disease

March 5, 2014
University of Copenhagen
Seventy-five percent of antibiotics in Danish fish farms is used to treat fish with enteric redmouth disease. With the help of 3-D scans, researchers have mapped how the fish are infected with the bacterium. The disease, which reduces fish well being and increases fish mortality in Danish fish farms, is harmless to humans.

Enteric redmouth disease is a bacterial infection that can kill fish, but is entirely harmless to humans. Symptoms typically take the form of a redness or bleeding in and around the mouth of the fish.
Credit: Image courtesy of University of Copenhagen

Fascinating 3D images of rainbow trout give researchers a crystal clear picture of how the bacterium causing enteric redmouth disease infects fish.

"The new scans show us that the fish are infected through their ultra-thin gills," explains postdoc Maki Otani, the Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences.

Educated in Japan, Maki Otani has supervised the scanning process, where advanced technology and precision combine to form a higher synthesis. For this reason, the research group can now map with extreme precision the bacterial infection (Yersinia ruckeri) causing enteric redmouth disease in fish.

The disease, which reduces fish well being and increases fish mortality in Danish fish farms, is harmless to humans.

The infection pathway

The researchers have scanned the ultra-thin gills of rainbow trout. The gills are a specialized organ whose chief function is to absorb oxygen from the water so the fish can breathe. Only two cell layers separate the outer water from the blood in the fish's small arteries. The new findings show that the bacterium infects the fish via a specific cell type in the gills.

The red spots mark the infected cells.

As little as 60 seconds after the bacterium is introduced into the aquaculture, its presence can be registered in the fish's bloodstream. The bacterium subsequently infects the fish via its intestine and the lateral line canal- a sensory apparatus running along both sides of the body.

Rare 3D scanner

The University of Copenhagen possesses a so-called OPT scanner (Optical Projection Tomography) -- a rare piece of equipment enabling researchers to monitor the infection with unparalleled precision.

"The research findings are presumably the first of their kind and the scanning images exceed our wildest dreams," explains associate professor Martin Raida, the Department of Veterinary Disease Biology, who is heading the project.

Among other things, he is conducting research in developing vaccines. The Danish fish production industry currently vaccinates its fish, also against enteric redmouth disease, but to date this has not solved the problem. Martin Raida hopes that the new knowledge can contribute to the development of a more effective vaccine against enteric redmouth disease. This will contribute to bring down the amount of antibiotics used and thus reduce the burden on the environment.

Story Source:

The above post is reprinted from materials provided by University of Copenhagen. Note: Materials may be edited for content and length.

Journal Reference:

  1. Maki Ohtani, Kasper Rømer Villumsen, Helene Kragelund Strøm, Martin Kristian Raida. 3D Visualization of the Initial Yersinia ruckeri Infection Route in Rainbow Trout (Oncorhynchus mykiss) by Optical Projection Tomography. PLoS ONE, 2014; 9 (2): e89672 DOI: 10.1371/journal.pone.0089672

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University of Copenhagen. "3-D scans map widespread fish disease." ScienceDaily. ScienceDaily, 5 March 2014. <>.
University of Copenhagen. (2014, March 5). 3-D scans map widespread fish disease. ScienceDaily. Retrieved November 30, 2015 from
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