Virus outbreak has experts worried for dogs

August 20, 2004

BY RAKSHA VARMA

Staff Reporter Chicago Sun-Times

Chicago has seen an outbreak of a distemper virus that can be deadly to dogs -- 76 cases reported in Chicago since April, while none were reported last year, the Department of Animal Care and Control said Thursday.

The virus is a 200-year-old killer said to be the leading cause of death in U.S.-born-and-bred pets up until the 1950s when specialized immunizations became available.

Officials don't know the cause of the outbreak but plan to meet next month to study it.

Humans and cats cannot contract the virus, which is fatal about 50 percent of the time in dogs, the department said. Pets that don't croak are usually prone to brain damage and other ailments, such as seizures, two-thirds of the time.

"Canine distemper is a serious threat," said Dr. John Lednicky, an assistant professor of pathology at Loyola University Chicago Stritch School of Medicine in Maywood. "Vaccinations help to keep your dog safe. But nothing is foolproof because the strains change so rapidly."

Canine distemper is an RNA virus that belongs to the same family responsible for measles in humans. Three different strains of the lethal disease swept through Chicago, Lednicky said, adding that outbreaks were present in 1998, 2000 and 2001.

Vaccinations, routinely administered in an annual veterinarian's physical, usually safeguard your pet against most strains.

Dogs that are not properly vaccinated contract the virus from the air, contact with other infected dogs in parks and exposure to wooded areas, the department said. Foxes, coyotes and raccoons, which inhabit wooded areas, are said to be the largest carriers of the disease.

There is no cure for the virus, which was first correctly described in the 18th century by Dr. Edward Jenner, remembered as the father of immunology and conqueror of smallpox, Lednicky said.

The virus was probably carried to Europe by Spaniards returning from an expedition to Peru.

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Chicago Tribune Feb 6, 2005

Killer disease returns to stalk dogs
By Peter Corner
Tribune science reporter

History's biggest killer of dogs, canine distemper, appears to be breaking out again, alarm: ing experts who thought vaccinations had vanquished it in the United States.
m the last year, epidemics of the incurable disease have been reported in Los Angeles, Phoenix, Atlanta, Dallas, Miami and Washington state. A distemper episode last year killed at least 120 dogs and halted adoptions in
shelters throughout the Chicago area before it was brought under control.
And the virus, while quieter now in Chicago, still poses a threat. "We're still receiving some animals straight from the street that are sick with active distemper," said Marek Dygas, chief veterinarian for the Chicago Department of Animal Care and Control.
Not only is distemper devastating to dogs—commonly resulting in vomiting, seizures, paralysis and death—but the highly contagious infection also can spread to wildlife with shattering impact. Its presence also might be a harbinger of other outbreaks, because owners who don't vaccinate their dogs against distemper are unlikely to protect - them against other diseases— including rabies, which can spread to people. , Experts urge pet owners to ensure puppies and adult dogs are vaccinated.
"This is an absolutely horrific disease. Get your dog immunized," said Ronald D. Schultz, a veterinary immunologist.
The incident at the city's municipal shelter, which normally sees only a handful of distemper cases a year and saw none the previous year, was of so much concern that a task force of academic scientists, veterinarians and infectious disease specialists was formed to look into why so many dogs were infected.
The scientists assumed that many animals brought to the shelter—often strays or abandoned fighting dogs—had not been vaccinated. "We see distemper in shelters , throughout the country," said Schultz, a key task force member. "It doesn't exist as a significant disease for the average pet dog anymore, because if you
vaccinate the dog as a puppy, you've [usually] got lifetime immunity"
But testing showed the percentage of unvaccinated dogs was even higher than expected. And the team remains concerned that lack of shots doesn't tell the whole story
The scientists worry that the virus has survived so long in this area because a new, vaccine-resistant strain of neurologic distemper is circulating. Maybe another virus is infecting animals, making them more susceptible to distemper. The task force still regularly meets,
and the scientific quest for answers continues.
Canine distemper virus is a deadly sibling of measles that attacks the respiratory, gastrointestinal and nervous systems. Until the 1950s, it was the most feared disease of dogs. "Before effective vaccines were developed, half of all litters—50 percent of all puppies in the U.S.—were dying from distemper," said Schultz, chairman of pathobiological sciences at the University of Wisconsin-Madison's School of Veterinary Medicine.
Dogs can contract distemper by exposure to viral particles from infected pets or wildlife that serve as reservoirs for the virus, such as foxes, wolves, coyotes, raccoons and skunks.
Unvaccinated puppies under 4 months are the most susceptible. Classic signs include coughing and sneezing, followed by a thick greenish discharge from the eyes and nose. Depression, lack of appetite, vomiting and diarrhea are common.
In advanced stages, the virus migrates from the face to the brain, causing "bubble gum" seizures where the dogseems to be chewing on air. These can progress to grand mal seizures and paralysis. There is no cure.
"We could only alleviate a sick animal's suffering by euthanasia, " Dygas said.
In recent decades, vaccination strategies have become so successful that experts in dog distemper are a vanishing breed.
"Most of us are either retired or dead," Schultz noted wryly. "Younger Veterinarians—including some being quoted as experts—may have never seen an active case of distemper. But if you have, you never forget it." Dygas, who has worked in countries where distemper is less rare, detected trouble at the shelter after a dog that had been adopted in April was returned when it started showing neurological symptoms. He ordered a distemper test, in addition to a postmortem rabies test.
Soon Dygas found Schultz, and they teamed up with virol-ogist John Lednicky, director of molecular virology at Loyola University Medical Center, to address a flare-up of distemper. One of the first things they did was test blood samples for antibodies to see how many shelter animals had been vaccinated. "Whenever something like this happens, it's usually a failure to effectively vaccinate," Schultz said.

Task force members said they were shocked to find that 65 percent of the dogs entering the shelter had no evidence of vaccinations—not only against distemper, but also against rabies. A 30 percent figure is more typical, Schultz said. Dygas said most of the infected dogs have been mixed-breed Rottweilers and pit bulls.
"They had been owned and then released on the street. They never saw a veterinarian before," he said. "When those animals were brought here, they already were in bad condition. They didn't have proper nutrition. Their immune system was not prepared to fight any kind of contagious disease."
Lednicky and his colleagues at the Conservation Medicine Center, a collaboration among Loyola, the University of Illinois College of Veterinary Medicine and Brookfield Zoo, have been studying dog distemper in Chicago-area raccoons for more than eight years. Their research revealed that the primary symptoms were neurological and that sick raccoons can infect dogs and, in some cases, zoo animals.
"That's a big concern," Lednicky said. "When a virus starts cycling back and forth among species, the rate of mutation can be speeded up. It was possible that modern distemper vaccines no longer would work."
To test that possibility, Lednicky used high-tech molecular techniques to isolate and sequence three strains of distemper virus from dogs that were dying at the shelter. He drove the samples up to Madison, where Schultz exposed vaccinated Wisconsin lab dogs to each viral isolate. The dogs shrugged off the challenges, indicating the three current vaccines still worked.
But Lednicky discovered an unusual strain of distemper virus circulating in this area, one closely related to a strain that primarily attacks the nervous system, causing acute and progressive inflammation of the brain and spinal cord. That could account for the neurological symptoms seen here in dogs and wildlife, he believes.
Researchers in Switzerland, who discovered the strain, have determined it to be much more virulent than commonly studied distemper viruses. Recently the Swiss asked Lednicky and Schultz to collaborate on further research. As he pieces together the puzzle, Lednicky still worries the dog disease might be masking something more dangerous.
"Is there a virus going around, similar to SARS, that is affecting animals and making them more susceptible to distemper? Can it spread to humans? Those are the questions I'm asking," he said.
The task force scientists credit the city's Animal Care and Control Department f®r recognizing there was a problem and seeking outside advice. But controlling an airborne disease in a large facility that processes and houses 26,000 animals each year proved to be arduous.
"What was happening early on—when the outbreak first occurred—was like pouring gasoline on a fire," Schultz said. "Every time they brought in a new, susceptible animal, it became infected immediately because of all the infection that was in the shelter."
Once the scientists increased awareness, Animal Care and Control began vaccinating every arriving dog. A 30-day moratorium on adoptions was instituted. Staff members donned disposable garments and sanitized their shoes before moving in and out of areas where animals were housed. A new quarantine protocol went into effect.
The epidemic eventually seemed to burn itself out, and the shelter restarted its adoption program. Dygas said the shelter now has no positive cases in the facility, at 2751 S. Western Ave.
Recently, shelter volunteers severely criticized the facility over hygiene issues and a slow response to the distemper epidemic. The director at the time of the outbreak, Nikki Proutsos, no longer works there.
Veterinarians in the area reported 27 confirmed cases outside the shelter last fall, but only one case since October, said Patricia Montgomery, executive director of the Chicago Veterinary Medical Association.
The task force scientists said Chicago should follow the lead of other cities in the U.S. that offer free distemper and rabies vaccinations for dogs as part of a public health program.
The Chicago Department of Public Health has no plans to sponsor such a program, said spokesman Tim Hadac, adding that "once Animal Care and Control gets a new director, we will doubtless touch base on any number of issues that affect both our agencies."
But such a program not only would be more humane to pets, but also would help protect wildlife, the scientists said.
Lednicky said he also is concerned because, as with West Nile virus, wildlife often is a bellwether of emerging human public health problems.
"Our studies were tantamount to a random sample of stray dogs in Chicago and suburbs—dogs most likely to come in contact with wildlife," Lednicky said.
"And that really scares me."

Multidisciplinary task force tackles Chicago distemper outbreak
Questions raised about vaccinations

November 1, 2004 JAVMA News

A task force of veterinarians, a virologist, and animal control officials is searching for the cause of a canine distemper outbreak in the Chicago area, and advising the city's municipal shelter on disease control and eradication measures.
Cases of canine distemper were first confirmed by laboratory tests in April; since then, more than 100 dogs have tested positive for the disease at the Chicago Department of Animal Care and Control shelter. Some of the dogs may have been infected at the shelter, whereas many others came in with the disease, according to Nikki Proutsos, the director of the Chicago department of Animal Care and Control. Additionally, area veterinarians have reported more than 20 confirmed cases outside the shelter to the Chicago VMA.
Some of the dogs that developed signs of distemper at the shelter had been vaccinated, said Dr. Dan Farmer, the director of Cook County Animal Control and a task force member. Proutos said it was hard to say whether enough time had passed between vaccinations at the shelter and exposure to the virus. And members of the task force are questioning whether too few animals have been vaccinated against distemper in the area, or whether the vaccines being used are not as effective as had been presumed.
"We don't know if routine vaccinations are protecting animals from the virus," said Dr. Sheldon Rubin, a private practitioner and task force member.
Dr. Marek Dygas, the supervising veterinarian, discovered the outbreak after he ordered a distemper test, in addition to a postmortem rabies test, for a dog that was returned to the shelter by adopters after it began showing neurologic signs, Proutsos said. Proutsos credited Dr. Dygas for his vigilance, and she said his professional experience in countries where canine distemper cases are more common helpec him to detect the disease. The dog, which had been adopted in April, was returned after developing neurologic signs; it had appeared healthy while at the shelter.
Proutsos said it's difficult to rule out previous distemper cases at the shelter because the shelter did not test for distemper in the previous
year. But the shelter has not seen this type of outbreak before.
"If we haven't changed what we've been doing in the last (several) years, there has to be something going on," she said.
A call to action
Canine distemper has become rare in dogs in the United States since modified-live virus vaccines became available in the 1960s. In fact, according to Dr. Rubin, many younger veterinarians may have never seen a case. The disease, however, has remained a substantial problem in some wildlife species—particularly raccoons. Infected wildlife can serve as a reservoir for the disease, passing it to dogs or, in some cases, zoo animals.
The outbreak in Chicago is unusual, said Dr. Julie Dinnage, the president of the Association of Shelter Veterinarians. Shelters in the northern United States rarely see cases of the disease, though it's more common in the South. Outbreaks in shelters are not common even when infected animals are detected, because distemper virus does not spread as easily as other viruses.
"We do have cases in some parts of the country, but it's not something that's devastating like parvovirus," she said.
Dr. Dinnage said it would take more research to determine the cause of the Chicago outbreak.
Members of the task force said they've contacted shelters across the country to find out whether they've experienced similar problems, and shelters in Georgia, Texas, and Washington state have seen the disease recently.
The officials from the Chicago VMA who are serving on the task force are attempting to gather information about the scope of the Chicago outbreak, said Patricia Montgomery, the executive director of the association. The VMA sent out mass e-mails and faxes to veterinarians, warning them of the outbreak and asking them to report the disease, which is not classified as a reportable disease by federal and state agencies. The Illinois State VMA also has sent information to members about the outbreak.
Containment a priority
The most immediate goal of the task force has been to advise the shelter on steps to stop the spread of the virus. That task has been complicated by the fact that the shelter handles more than 26,000 animals each year, including some of the highest risk populations—the city's strays and feral animals, and nuisance wildlife. Also, the disease can spread through droplets of body fluids.
On the basis of the task force's recommendations, the shelter offi-
cials have taken several steps, including the following:

• Instituting a 30-day moratorium on dog adoptions starting in August
•Transferring or referring healthy or owner-relinquished animals to other shelters
• Designating an animal control truck to exclusively transport nuisance wildlife
• Stopping the housing and euthanatizing of nuisance wildlife inside the facility
• Requiring shelter staff members to put on disposable garments and sanitize their shoes before moving among the areas where animals are housed

Veterinary staff are also immediately examining and vaccinating each dog that enters the facility. Additionally, a new quarantine protocol has been implemented. The facility is arranged into several rooms or pavilions, each with separate outdoor air exchange systems. The shelter staff has instituted a system by which a pavilion is power washed and sanitized, and then new dogs are brought in.
After the 45-kennel pavilion is full, the dogs inside are quarantined and observed for three weeks. If none of the dogs develops signs of distemper, all the dogs become eligible for adoption or transfer to other facilities. Unfortunately, if any dog develops signs of the disease, all animals in the pavilion must be euthanatized, Dr. Rubin said.
Task force members agreed the best way to control the disease is at the veterinarian-client-patient level, where veterinarians can ensure that dogs are vaccinated, advise clients to prevent their dogs from being exposed, and watch for signs of disease. Once the disease reaches a shelter that handles thousands of animals, it is much more difficult to control, Proutsos said.
Searching for clues
Veterinarians and a virologist from the Conservation Medicine Center of Chicago at Loyola University's Stritch School of Medicine—a collaborative effort between Loyola, the University of Illinois College of Veterinary Medicine, and the Brookfield Zoo—are also on the task force. They've been studying canine distemper in area raccoons for more than eight years. Now, they are working to identify the strain of the virus causing the outbreak in dogs, and trace its source.
The center's studies have revealed that canine distemper virus causes outbreaks in the local raccoon population roughly every three years. Various strains of canine distemper virus recently cycled through the raccoons. Research on these strains was published in the Virology Journal, an online journal, on Sept. 2, and is available to the public, free, at www.virologyj.com/content/1/1/2.
On the basis of preliminary information about the genetic sequence of the virus causing the current outbreak, John Lednicky, PhD, a virologist from Loyola University Medical Center who also works with the center, said it appears to be a variant of the virus that cycled through raccoons in 2001. He said it's too early, however, to determine whether the
disease was transmitted from raccoons to dogs or vice versa.
Dr. Lednicky said he hopes to partner with other researchers to conduct challenge tests on dogs to answer the task force's questions about the role of vaccines in the outbreak. He plans to provide Ronald Schultz, PhD, of the University of Wisconsin with canine distemper virus isolated during the current outbreak. Dr. Schultz, an expert on distemper vaccinations and disease in the United States, has offered to conduct challenge tests on dogs to see whether current vaccines are effective.
"It will give us an idea whether people haven't been vaccinating, or whether the virus has drifted significantly and the vaccines are less protective," Dr. Lednicky said.
Ultimately, task force members hope their multidisciplinary approach will help end the current outbreak and provide information that will prevent future outbreaks.
Dr. Thomas Meehan, the head of the Department of Veterinary Sciences at the Brookfield Zoo and a member of the center, said the approach has become more common since the emergence of West Nile virus, which highlighted the importance of coordination and communication between disciplines.
"The diseases don't notice the difference between human medicine, veterinary medicine, and ecosystem health," he said. ^
— BRIDGET M. KUEHN

Comments on canine distemper outbreak

JAVMA, Vol 226, No. 1, January 1, 2005

I suspect that a large percentage of veterinary practitioners today have never diagnosed a case of canine distemper. When I first started in practice over 40 years ago, it was not unusual to see several cases of distemper every week. It is a devastating disease. We, with the cooperation of our dog-owning clientele, have been successful in reducing the incidence of distemper, at least in our area of the country, to the point where I have not seen a case for years. That, in my opinion, is a great success story.
It is now thought that we are overvaccinating. Possibly so, but 1 think we would do well to rethink our new emphasis and weigh the risk of a rare adverse effect of vaccinating annually against the frightening and devastating risk of allowing distemper back into our canine population.
Admittedly, at the time the JAVMA published its news story on distemper (November 1, 2004, pp 1315-1317), it was not known that the Chicago outbreak was not a new strain. My point remains. Consider one risk against the other before relaxing our fight against canine distemper as well as other contagious diseases that we have been so successful in controlling in pets. Think about our colleagues in human medicine who are confronted today with the problem of what to do about a population with no known protection against smallpox and the possible ramifications.

William A. Dorsey, VMD

Prince Frederick, Md

CANINE DISEASE DOWNS TIGER
Veterinarians from the Wildlife Conservation Society have confirmed the first known case of canine distemper in a wild Siberian tiger in the Russian Far East. The tiger died, despite treatment. In 1994, canine distemper virus killed one-third of lions in the Serengeti. Domestic dogs were the source. In the Russian Far East, preliminary studies indicate that 67% of dogs sampled have been exposed. As humans and domestic animals encroach on tiger habitat, disease becomes an increasing threat to tiger conservation. There are fewer than 500 Siberian tigers
left in the wilds of Russia, (www.medicalnewstoday.com/ medicalnews.php?newsid=12767; accessed September 2004)