Researcher: Healthy dogs as well as sick ones can shed virus

September 16, 2013


AKRON, Ohio — A retired Ohio State University veterinary immunologist and pathologist who 15 years ago helped identify a deadly pig virus is praising a former student for raising concerns about dogs dying of a mysterious disease.

Dr. Steven Krakowka said it took courage for Dr. Melanie Butera to alert authorities when she saw something new and disturbing at her Canal Fulton, Ohio, veterinary practice.

"She took a big chance. If she’s wrong, she could get her head chopped. But she’s not wrong," Krakowka said this week from his Ohio State office where he continues to conduct research part time.

He knows firsthand the risks of stepping out.

Krakowka and researchers John Ellis of Canada and Gordon Allen of Ireland discovered porcine circovirus 2 (PCV2) in 1997. They had trouble getting the U.S. swine industry to believe they had discovered a new disease and spent more than four years traveling the world talking about how to deal with it.

"Finally, the U.S. swine producers and particularly the swine infectious disease veterinarians had to admit that this disease was real and we had it in swine populations and that we — John, Gordon and myself — were absolutely correct," Krakowka said.

Today, the vaccine developed to control the disease is given to pigs born worldwide, saving pork producers an estimated half a billion to a billion dollars a year in potential lost revenue.

The questions in today’s mystery are large: Is this the pig virus and has it jumped species? Are dog deaths in California, Cincinnati and Canal Fulton due to the same virus? Is the virus making dogs ill on its own, or is it working in conjunction with something else?

The virus originally was identified in dogs in California, where it was labeled canine circovirus. It might be spread by feces and respiratory tracts, which is the case with porcine circovirus 2.

A study that researchers at the University of California, Davis, School of Veterinary Medicine published in April said dogs were only the second mammal in which circovirus has been detected. It has also been found in pigeons, geese and canaries.

The University of California-Davis results indicated that circovirus, alone or in co-infection with other pathogens, might have contributed to illness. On Tuesday, the Veterinarian Information Network, an online community for veterinarians, reported that samples from three infected Ohio animals had been delivered to Dr. Patricia Pesavento, an associate professor of pathology, microbiology and immunology at the university. One tested positive for DogCV.

The network’s story did not indicate where the samples came from in Ohio. In question is whether the circovirus identified in a Canal Fulton dog that died last month is the same illness that killed three dogs and sickened a dozen others in Cincinnati in early August.

Pesavento said previous researchers identified 10 animals that are infected with canine circovirus.

Pathologists have determined "circovirus is part of this; we don’t know if it’s the same agent killing all of these animals," she told the network.

NAME IS IMPORTANT

Krakowka said the distinction that researchers gave the virus an individual name is telling.

"The California doctors have isolated and sequenced this virus and compared it. I don’t know how close it is to porcine circovirus 2. My guess is it is sufficiently distinct to get the name ‘canine circovirus’ rather than ‘pig circocvirus in dogs,’" Krakowka said.

Now, he said, the question is whether the virus itself makes the dogs ill, or whether the virus acts in conjunction with something else.

"In other words, is circovirus itself causing the disease or is the dog sick of something else and it happens to be carrying circovirus?" said Krakowka, among the most cited veterinary research scientists in the world, according to Science Watch International.

Originally, pathologists studying PCV2 could not re-create the virus by itself in the laboratory, Krakowka said. It needed the help of other viral infections, which are not lethal on their own, to produce the disease also known as "wasting disease."

"There were a number of manipulations we had to do to get the virus to work. It wasn’t just a case of inoculating them to get it to work. It didn’t. We eventually figured out that what was required (was) co-infections with other agents. The virus all by itself does not cause the disease. It needs help," Krakowka said.

If the new virus is found to parallel PCV2, healthy, normal dogs might be carriers that shed the virus through feces and respiratory tracts for several weeks and months, Krakowka said.

"Dogs that spend most of their lives indoors are going to be fine. But the dogs that are out there wandering around chasing chipmunks in the park, they are going to encounter other dogs with the disease — including the dogs folks saved. It’s very likely that he is shedding circovirus out of every pore. It is very likely he is the source of infection to all sorts of dogs in the neighborhood," he said.

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STATE INVOLVEMENT

On Friday, the Ohio Department of Agriculture posted a notice on its website asking veterinarians to contact the Division of Animal Health if they suspect any patients are suffering from the same symptoms affecting dogs in the Akron-Canton area and Cincinnati.

"While we continue to work diligently to identify what is making these dogs sick, we are asking Ohio’s veterinarians to help by contacting our laboratory for consultation if they suspect they are treating a related case," State Veterinarian Dr. Tony Forshey said.

Affected dogs have exhibited similar symptoms including vomiting, bloody diarrhea, weight loss and lethargy, according to the agriculture department’s news release.

"Because the symptoms being exhibited can also be linked to other known illnesses, additional analysis and information is needed to determine if this virus alone or in co-infection contributes to illness and death in dogs," Forshey said.

MOVING FORWARD

Krakowka said he expects events will quickly move well beyond private practice veterinarians who say they have found something new.

"That’s where it’s going — research papers, grants, meetings, symposiums, etc. And the drug companies are on this, you can bet, and people are already gearing up to go after it," he said.

He called Butera "a very astute clinician to separate normal sickness from something else."

"The fact that she’s in private practice rather than in an academic environment makes it even more amazing because there is almost no incentive to think outside the box when you are a practitioner and you are trying to make a living," he said.

He sees a parallel between his experiences and those Canal Fulton veterinarian Butera is going through after notifying authorities of her suspicions.

"That’s a huge leap of faith to have the mental and the emotional courage to get out in front of this because nobody else has told you about it. And there you are, right on the leading edge, saying we got something new. And people paid attention," he said.

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