#31 – Canine Distemper: the Dog Virus That Threatens Whole Species

00:00:05: After that, the animals can recover and they can recover relatively quickly.

00:00:11: But if the virus spreads to their central nervous system which is often the case then it's usually or very often a death sentence for an animal.

00:00:33: Birological with Florian Kramer.

00:00:46: Hello and welcome this week episode of Biro logical.

00:00:50: This was recorded on September seventh.

00:00:52: twenty-twenty six in Bergen Norway.

00:00:56: I thought today we're going to talk about animal disease that is problematic for dogs, but also a lot of other animals.

00:01:04: And the diseases are Canandistampa virus.

00:01:07: So now what's canan distampa virus?

00:01:10: Canan distampor virus is a paramexovirus more specifically a morbidivirus which means it closely related to measles virus human measles Virus But its also closely related Ring the best virus, which is a virus that used to circulate in cattle but was eradicated a while ago.

00:01:29: Like all baromixoviruses this virus has a minus sense single strand RNA genome just one genome strength or no segments.

00:01:37: it has a coding capacity of about sixteen thousand base pairs so that's sixteen thousand letters and it encodes for number of proteins The end protein The P-protein, which also has the C and V variants.

00:01:52: The M protein... ...the F protein,... ...the H protein & L protein.

00:01:57: If you look at the virions they're typical Bermixovirus virions.

00:02:02: They are about one hundred fifty to two hundred fifty nanometers in diameter and they are pleomorphic Which means that it's roundish but not really nicely rounded.

00:02:10: You can have all kinds of weird shapes And like all Bermexoviruses In my opinion there quite ugly.

00:02:16: When we looked how The virion is structured, we have the RNA on the inside.

00:02:22: The RNA's protected by a nuclear protein and then associated with polymerase, the L-protein And also the phosphoprotein.

00:02:31: Then we have matrix that's in the inner side of the lipid envelope which stabilizes the virion.

00:02:38: In the lipide envelope you've got two proteins.

00:02:41: One is called hemagglutinin.

00:02:43: Another one is called f-proten or fusion protein.

00:02:47: Hemagglutinin is H and the fusion protein is F. The interesting part here, they're basically named to.

00:02:55: same.

00:02:55: as for measles... ...and in measles the H or hemagglutenin-protein can hemaglutinate red blood cells so it basically can clamp them together that you can test easily.

00:03:09: That's something a lot of viruses do including influenza virus also has an hemag glutein.

00:03:16: It's misnamed here in a way because the hemagglutinin of Canon distemper virus does actually not hemaglutinate.

00:03:22: And so, the virus uses this hemag gluteinine protein to bind to cell surface.

00:03:27: it binds two different receptors on the cell surface.

00:03:30: On immune cells it binds to receptor called CD- hundred fifty or SLAM and other cells can bind to Nectin.

00:03:38: four The interesting part is that the virus fuses directly at the cell membrane with the cell and releases the genome into the cells.

00:03:48: So it's not taking up in an endosome, but it's fusing directly to a cell membrane.

00:03:53: A little bit about history of the virus.

00:03:55: maybe I should explain their name first.

00:03:57: so canine distemper virus that distempo basically means that bodily humors are disturbed not mixed, right?

00:04:08: And I guess that's kind of where the name comes from.

00:04:12: The disease itself was first reported or described in Spain in seventeen sixty-one probably has been around before that for a while and then Edward Jenner described it also in eighteen oh nine.

00:04:25: so Edward Jenners was the person who came up with vaccines.

00:04:29: he also described this disease.

00:04:35: French veterinarian Auricaré, postulated that the disease was caused by a virus and it was then confirmed in nineteen twenty-six.

00:04:45: By late law and Duncan already in nineteen twenties.

00:04:48: three The first vaccine was made against Kennedy's tempo virus by Vittorio Puntoni In Italy And what he did?

00:04:57: Was used inactivated dog brain tissue from animals who were infected with the virus on died of the virus.

00:05:04: But the first commercial vaccine became available in the nineteen sixties and we'll talk a little bit about vaccines later.

00:05:12: So how do animals get infected with the virus?

00:05:14: And when I say animals, it's dogs but also lot of other animals will come to them in few minutes.

00:05:22: basically dogs get infected by inhaling respiratory droplets that have the virus or direct contact animals that are infected with bodily fluids from animals, and the virus in general is pretty contagious which is similar to measles.

00:05:44: Initially the virus infects lymphatic tissue in respiratory tract so basically immune cells And then after two or four days it starts spreading.

00:05:57: a virus starts to spread throughout the body, in the blood.

00:06:00: we call it varemia.

00:06:02: So there is a varemia after two or four days and then other organs get infected displaying thymus, the bone marrow so basically immune cells there but also respiratory tract, GI tract, other organs And the virus can reach the central nervous system.

00:06:20: that usually happens eight-to ten days And that's, of course problematic.

00:06:27: if a virus replicates in the central nervous system.

00:06:30: Usually it means it is a severe infection.

00:06:32: This doesn't happen with Kennedy's tempo virus all the time but happens often In terms of symptom onset.

00:06:38: incubation times between three to seven days and initial symptoms are fever lack of appetite lack activity.

00:06:47: in these animals The fever can be pretty high It could go up to forty one degree Celsius.

00:06:55: And then GI tract symptoms show up, vomiting, diarrhea.

00:06:59: Often bloody diarrhea and bloody vomit excessive salivation.

00:07:04: this can lead to dehydration.

00:07:06: the respiratory tract is affected often starts with a runny nose coughing shortness of breath really pneumonia.

00:07:14: these animals they also get rash similar to measles might be harder to see in dogs.

00:07:21: after that The animals can recover and they can recover relatively quickly, but if the virus spreads to their central nervous system which is often the case then that's usually or very often a death sentence for the animals.

00:07:36: And so the symptoms you see when the virus goes through the central nervous systems are sensitivity light and other stimulation circling... So animal runs in circles.

00:07:50: incontinence can be a symptom of CNS involvement in general the duration of motor capabilities so that the animals cannot really walk well anymore, move well any more.

00:08:05: So thats usually sign off very severe disease and bad outcome.

00:08:10: And so... Usually when young dogs or puppies get infected mortality rate or the case fatality rate is about eighty percent.

00:08:21: If all the dogs get infected, dogs that have no immunity... The case-fatality rate usually around fifty per cent.

00:08:29: So it's a highly lethal disease.

00:08:31: in dogs who are not vaccinated There can also be long term consequences.

00:08:37: What this often seen as there growth of the nose and footbeds In other words caroteno sides start to grow at the higher rate in these animals.

00:08:49: This is also for the footbeds, this is described as a foot bed disease.

00:08:54: that can be muscle twitching in animals to survive the disease.

00:08:59: and if young animals get infected they really could have issues with their teeth or animal which of course lasts until all life.

00:09:11: There's also a syndrome associated with these infections that is similar to something seen in measles, humans.

00:09:18: So often when kids get infected with measles at very young age they might recover.

00:09:23: but then years later the get encephalitis and it's called for measles SSBE or subacute sclerosis by an encephalitis almost uniformly deadly.

00:09:34: And you see something similar in dogs as well.

00:09:36: that's called old dog encephalitis.

00:09:39: So, it is something the dogs can get and survive.

00:09:42: Can an distemper virus infection?

00:09:44: But then somehow the virus stays in their brain... ...and at a very late point of life starts to cause encephalitis there.

00:09:53: often Young dogs or puppies between three and six months of age are susceptible.

00:09:59: If they're younger, They often have maternal antibodies from their mothers that protects them.

00:10:06: but then within three to six months this maternal immunity goes away And that's when you become most susceptible As I mentioned the case for deli dirates or the mortality rates in these animals.

00:10:19: young animals Are really high eighty percent sometimes even higher.

00:10:25: but even for adult dogs when they have no immunity, the infection is very severe.

00:10:30: The good thing there are vaccines against Canonys Tempovirus.

00:10:34: They're a live vaccine called MLVs or Modified Live Vaccines.

00:10:39: There's recombinant Canonys Tampovirus vaccines which often based on canary box viruses that express the glycoproteins of Canonys tempovirus and also inactivated vaccines.

00:10:50: so certainly something to protect dogs.

00:10:54: Usually they need to get vaccinated quite often, typically at eight weeks of life.

00:11:00: then again twelve weeks and sixteen weeks.

00:11:04: so three initial vaccinations.

00:11:07: Often a boost is given after fifteen months supposed to get re-vaccinated against the Canon D-stemper virus every three years.

00:11:16: And, the immunity that you get from these vaccines is not perfect.

00:11:19: so animals can still be infected but typically if they have enough immunity then don't get symptomatic.

00:11:26: I mentioned earlier this virus also affects a lot of other animals.

00:11:31: So right now the virus circulating worldwide in the dark population which is imperfectly protected by vaccine, so in many countries there is the vaccination rates are not that high even in Europe and North America.

00:11:48: The vaccination rates aren't perfect And so the virus keeps circulating just like measles does in humans.

00:11:54: But the problem is unlike measles which basically restricted to humans this virus jumps into a number of other species and causes issues There.

00:12:04: So it has been reported in red pandas dog-like animals including wolves and foxes.

00:12:12: So basically wild canids in Asian elephants, in large cats.

00:12:19: so typically it doesn't really affect house cats that much.

00:12:22: but lions for example are susceptible And that's problematic.

00:12:25: of course tigers can get it hyenas ferrets and ferret like animals badgers.

00:12:32: some primates can get infected But not humans bears, raccoons, kanks.

00:12:37: So basically tons of different animals that can get infected and in many of them the outcome is as severe as in dogs.

00:12:46: And thats really a conservation issue because As I mentioned The virus jumps from the dog population into these wild animals.

00:12:54: Canada's tempo virus has caused huge issues and serengeti lions in Africa where in three to four, there was a population decline of about twenty percent.

00:13:07: And these animals are already endangered.

00:13:09: the Ethiopian wolf is really affected by Canaan distemper virus and that's also an endangered species.

00:13:18: There even ideas that the disappearance of the Tasmanian tiger was also influenced by Canan distempo virus and lost due to Canan Distempo Virus.

00:13:27: In addition eradication campaigns by humans.

00:13:31: There's also an interesting related virus, closely-related virus and that is a foci in this tamper virus.

00:13:38: so it's a virus that infects seals and related animals And the idea here is that this virus split off around seventeen hundred from canine.

00:13:47: this tampovirus then started to circulate in seals mostly circulating in harb seals, which don't seem to get sick that much when they are infected.

00:14:00: So it seems the reservoirs were in a way but it crosses from harp seals into other seal species every now and then.

00:14:09: so in nineteen ninety-eight for example Harbour seals got infected at North Sea.

00:14:13: in Europe about eighteen thousand of them died.

00:14:17: That was one third population of harbour seals there.

00:14:21: I think gray seals are susceptible too.

00:14:24: In that nineteen ninety eight outbreak, about three hundred of them died as well.

00:14:30: and since then there have been additional large outbreaks in seal populations where tens of thousands of animals died And they're also in some parts of the world endangered.

00:14:42: for this reason it's a conservation issue.

00:14:46: The good thing is typically no infections in humans.

00:14:51: This might be because the virus just can't infect us, they're incompatibilities.

00:14:56: But on the other side there's also cross-protection from measles immunity and most human adults hopefully through vaccination but sometimes also through infection have measles immunities and that cross protection probably plays a role in the fact we don't see Canada's tempo virus in humans which is great in many species a very deadly virus and as I said like measles it's pretty contagious.

00:15:24: Yeah so to summarize this canan distemper virus is a very important and significant disease for dogs but also for many different wild animal species.

00:15:33: the good thing is there are vaccines for canan destemper viruses that are offered and routinely used in dogs, So if you have a dog make sure its vaccinated against Canan distember virus to protect your dog, to protect other dogs and also the protected wildlife.

00:15:51: And that's it for today!

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