Nav: Home

Discovery of new bacteria complicates problem with salmon poisoning in dogs

November 03, 2016

CORVALLIS, Ore. - Researchers at Oregon State University have identified for the first time another bacterium that can cause symptoms similar to "salmon poisoning" in dogs - and may complicate the efforts of Pacific Northwest pet owners to keep their dogs protected and healthy.

The Pacific Northwest, from northern California to central Washington, is the only region of the world in which dogs face this potentially deadly health threat. It's caused by a complicated life cycle that includes a common freshwater snail that harbors a fluke worm, and the fluke, in turn, carries the bacterium Neorickettsia helminthoeca. The bacterium is the actual cause of salmon poisoning.

The underlying problem is not new. Dogs that died after eating uncooked, infected salmon were first noted in the Astoria Journal in 1814, not long after Lewis and Clark visited the region.

The conventional wisdom, however, has been that dogs are usually immune to salmon poisoning after they have once been infected, treated with antibiotics and recovered - giving pet owners at least some assurance that it's a problem they no longer need be concerned about.

The new discovery makes it clear the issue is not that simple.

In the infectious process that leads to salmon poisoning, the fluke is released from snails, which then infect salmon and other freshwater fishes. The life cycle is completed when a mammal eats an infected fish - in this case, dogs get sick from eating raw or undercooked salmon. The possible occurrence of "salmon poisoning" is actually dictated by the geographic distribution of the snail.

Another bacterium called "SF agent," however, has been found for the first time in a salmonid fish anywhere in the world, researchers report in a recent study in Veterinary Parasitology. The fluke host for this bacterium is Stellanchasmus falcatus.

"SF agent can infect dogs that eat salmon or trout, and it can cause a mild fever in dogs and other symptoms that can resemble salmon poisoning," said Michael Kent, a professor of microbiology in the OSU College of Science and College of Veterinary Medicine, and co-author of the study. "It can also be treated with antibiotics, but may not offer immunity to dogs that could be later exposed to the actual salmon poisoning bacterium. A pet owner might believe their dog is protected, when it isn't."

The larval stages of the worm that carries Neorickettsia helminthoeca were first associated with the disease in 1911, and in 1950 the actual bacterium was confirmed as the cause of salmon poisoning. It's in the same bacterial family as SF agent - meaning pet owners must now understand their dogs may face two related Neorickettsia pathogens - but one causes only a mild illness, while the other can be deadly.

Veterinary doctors, Kent said, routinely have treated animals based on their clinical signs, because the eggs of the fluke may be hard to find in dog feces, and the bacterium is difficult to culture from dog blood. Left untreated, dogs with salmon poisoning can die in a week to 10 days, often from severe hemorrhaging and internal ruptures. The ultimate fatality rate can approach 90 percent of untreated cases.

The bottom line, he said, is that pet owners should not make any assumptions about whether or not their dogs may have immunity to salmon poisoning. Kent said he has received several reports from local veterinarians documenting dogs contracting salmon poisoning more than once.

With the new awareness that different bacteria can cause similar initial symptoms, pet owners should know that dogs displaying such symptoms may or may not have a serious health problem.

The fluke worm, but not the bacterium, can also infect humans. Humans do not contract salmon poisoning, but may develop a relatively mild gastrointestinal illness. Either freezing or cooking infected fish will kill the worms.
-end-
This research was supported by the National Institutes of Health and done in collaboration with researchers from the University of North Dakota, Georgia Southern University, and the Woodburn Veterinary Clinic in Woodburn, Ore.

Editor's Notes: Video interviews and audio are available with this story.

Oregon State University

Related Bacterium Articles:

New study explains extraordinary resilience of deadly bacterium
Researchers at the University of Maryland have identified how the pathogenic bacterium Pseudomonas aeruginosa uses tension-activated membrane channels to stop itself from swelling up and bursting when it is suddenly exposed to water.
Tiny bacterium provides window into whole ecosystems
MIT research on Prochlorococcus, the most abundant life form in the oceans, shows the bacteria's metabolism evolved in a way that may have helped trigger the rise of other organisms, to form a more complex marine ecosystem with overall greater biomass.
Common bacterium may help control disease-bearing mosquitoes
Genes from a common bacterium can be harnessed to sterilize male insects, a tool that can potentially control populations of both disease-bearing mosquitoes and agricultural pests, researchers at Yale University and Vanderbilt University report in related studies published Feb.
Sponge bacterium found to encapsulate arsenic drawn from environment
A new Tel Aviv University study sheds light on a unique biological model of arsenic detoxification.
Bacterium lassoes its way from the mouth to the heart to cause disease
The human mouth can harbor more than 700 different species of bacteria.
Complex bacterium writes new evolutionary story
A University of Queensland-led international study has discovered a new type of bacterial structure which has previously only been seen in more complex cells.
Planctomycete bacterium's internal membranes contain nuclear pore-like structures
A planctomycete bacterium features structures embedded in its internal membranes which resemble eukaryotic nuclear pores, according to a study published Feb.
Bacterium named after UQ researcher
University of Queensland microbiologist Emeritus Professor John Fuerst has a new bacterial genus (a group of related organisms) named in his honor.
New point of attack against stomach bacterium Helicobacter pylori
There is a strong suspicion that Helicobacter pylori is linked to the development of stomach cancer.
New evidence shows how bacterium in undercooked chicken causes GBS
A Michigan State University research team is the first to show how a common bacterium found in improperly cooked chicken causes Guillain-Barre Syndrome, or GBS.

Related Bacterium Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...