New strain of distemper virus breaches North American borders

You try to do the right thing.

In this case, the right thing was an animal-rescue group saving dogs from a Korean meat market and shipping them to North America last October so they could be adopted out to forever homes.

Only one of the dogs turned out to be something of a forever home himself: He was likely acting as host to the Asia-1 strain of canine distemper virus (CDV), which had not previously been reported in North America.

The sick dog developed a cough and began acting lethargically about two weeks after his arrival. Ten days after that, he developed muscle twitches, then seizures. After the dog was euthanized, Cornell University’s Animal Health Diagnostic Center (AHDC) tested samples from dog. An initial suspicion of dog flu proved false when the samples tested negative for canine influenza, but positive for CDV, and nearly identical to the Asia-1 strain of CDV currently active in East Asia.

Scientists at AHDC identified the virus and say it likely poses little threat to US dogs, depending on their immunization status.

“It is my belief that dogs who are currently immunized for CDV should be OK if challenged with the Asia-1 strain,” Edward Dubovi, PhD, professor of population medicine and diagnostic sciences at Cornell and director of the virology laboratory at the AHDC, told NEWStat. “The emphasis here is ‘immunized,’ which is not the same as vaccinated. Reports that ‘vaccinated’ dogs have clinical distemper are not really valid unless their immune status was previously known, which is never the case.”

Although the Asia-1 strain may pose little threat to the companion animal population, the AHDC also warns that it could take a serious toll on wild carnivore populations should it come into contact with wildlife.

“Well-meaning people are trying to save animals, but when you move animals, you move their infectious disease,” said Dubovi. “If this particular Asia-1 strain got out into the wildlife population, then it’s here forever, because you can’t get rid of it once it hits wildlife.”

“Thousands of cases of distemper occur each year in wildlife such as raccoons, skunks, coyotes, and foxes,” Dubovi added. “Domestic dog distemper cases are not rare, particularly in shelter operations in the South and Southwest, where vaccination rates are very low.”

CDV has also been found in wolves and ferrets and has been reported in lions, tigers, leopards, other wild cats, and even in seals.

CDV is highly contagious and commonly travels between hosts through the aerosols emitted when dogs bark and cough and through urine and feces. The disease starts with respiratory symptoms, such as coughing and pneumonia, and progresses into gastrointestinal illness and neurological problems. Most dogs in the United States receive vaccines for CDV to protect against native North American strains.

“For a dog presenting with CDV signs, there is not much that can be done other than monitor the course of the disease,” Dubovi said. Treatment of CDV typically consists of supportive care and efforts to prevent secondary infections; control diarrhea, vomiting, and neurologic symptoms; and administration of fluids to reverse dehydration. “Should the animal become neurological, then he might need to be [euthanized].”

Dubovi recommended that hospital staff collect information on the travel history of any dog who presents with CDV signs, and also information on where they’ve recently lived. “If from a shelter, the facility should be contacted to alert the staff as to the need for a change in their vaccination program,” Dubovi added.

CDV is a particular problem in shelters, where dogs infected with must be separated from other dogs to minimize the risk of further infection.

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