photo of a dog in a cage, raising its paw

The Round Barn:
How are rabies, African Swine Fever (ASF),
and imported dogs interconnected??

Rabies is a horrible viral disease that affects the neurological system. Through the help of the legally required
canine rabies vaccine in the US, cases of humans infected with rabies  is lower than other parts of the world.
African Swine Fever (ASF) is the world’s oldest virus which is deadly for pigs and can be transmitted by dogs.
Dogs can’t become sick with ASF, but they can shed the virus after consuming infected pork.
Dr. Lowe and Dr. Mitek break down infectious disease management and how ASF, rabies, and imported dogs
are all interconnected in this episode of the Round Barn podcast.

A transcript of this episode is available below.


 

released November 5, 2021

Twitter  |  Email

 

Dr. Ashley Mitek: I'm Dr. Ashley Mitek, and you are...?

Dr. Jim Lowe: Dr. Jim Lowe.

Dr. Mitek: And today, we are going to talk about the very scary and very fatal rabies virus.

Dr. Lowe: Welcome The Round Barn.

Dr. Mitek: We got on this topic because we recently had a death in Illinois that we haven't seen in decades, I think it was 1954 since the last human died of rabies in the U.S. And that was a little bit scary and shocking. I don't know if you saw those headlines. That's a disease we deal with a lot in veterinary medicine. We don't see it a lot, but we certainly deal with the vaccine. Do you want to talk about the case, what happened to that guy?

Dr. Lowe: Yeah. So, rabies is a horrible viral disease that causes neurologic symptoms and infects, actually, the brain, infects nervous tissue. And it was what we might think of as a disease of the past, because it's 100% preventable today.

Dr. Mitek: And how is it preventable?

Dr. Lowe: We can vaccinate. And we primarily vaccinate dogs. Dogs transmit it to humans. But, wildlife are also a reservoir, in particular in the case of bats. And so, that's what happened in this case. But, we don't see rabies in the U.S. because we have a highly vaccinated population. And so, what apparently has occurred here, at least in the news reports - we weren't involved directly. News reports say that this gentleman had apparently some bats living in his house - which, believe it or not, is not that uncommon. Bats can live in populated communities, so, this does happen, this is a potential source of rabies, and other diseases. So, the guy had bats in his house, and he got bit by a bat, and then he refused the post-exposure prophylaxis, which is actually another round of vaccination, which would have protected him. Rabies doesn't grow that fast. So, we've got really great protection either pre-exposure - you and I are both vaccinated as veterinarians, we got vaccinated against rabies. But, if you get bitten, then they can do post-exposure prophylaxis and immunize you, and actually keep you from getting the disease. And so, this chap apparently chose not to take the prophylaxis.

Dr. Mitek: We talk about core vaccines in dogs and cats, I don't know if you phrase it the same way in cattle and pigs.

Dr. Lowe: Well, no, it's a bit different, but the same idea, yep.

Dr. Mitek: And then, in kids, right, we have certain vaccines that we just...

Dr. Lowe: Yeah, MMR and DBT right. We think about, right, yeah, measles, mumps and rubella, and diphtheria, and tetanus-

Dr. Mitek: Are you a pediatrician? [LAUGHS]

Dr. Lowe: No, but when you do infectious disease for a living, you think about these things a lot, right?

Dr. Mitek: Oh, okay. So, why don't we vaccinate kids for rabies?

Dr. Lowe: We vaccinate dogs - let's go back one step. So, rabies itself, natural reservoir is probably bats, we think, as it is in coronavirus, and some other things. So, bats are an interesting thing-

Dr. Mitek: Why are the bats always the ones?

Dr. Lowe: I don't know. We do know, right, it is this habit of them living near people. When we think about infectious disease, it's exposure to susceptibles. And so, because bats are not scared to live with people, they probably are blamed for more things, or actually create more things, than those that want to go live in the wild and are scared of people. So, you've got bats that are infected. And then, they can transmit the virus primarily through saliva. But dogs are the other reservoir. So, canines - not domestic dogs, all canines - can be infected. And so, we have for a really long time vaccinated dogs against rabies. It's one of the few vaccines in veterinary medicine that's legally mandated. And the interesting bit, it's not mandated by the veterinary authorities, people I work with every day. It's actually mandated by Public Health.

Dr. Mitek: Because it protects people.

Dr. Lowe: It's all about protecting people. It's not about the dog, it's about humans. It's a zoonotic disease. It's a transmissible-to-humans disease. And so, we vaccinate dogs to protect people. So, we can vaccinate people, but because the disease is so rare, and the vaccination is relatively hard, right - we had to have three rounds of vaccine. If you all thought the COVID vaccine sucked, you haven't had rabies vaccine. And the third dose of rabies vaccine can be pretty rough for a lot of people. You really get a fever and are sick afterwards. But compared to dying, it was not a particularly complicated choice for me to get the rabies vaccine a long time ago. And the immunity appears to be lifelong, right? I don't know the last time you had your titers checked, but mine were still as good as it was when I was vaccinated.

Dr. Mitek: Yeah.

Dr. Lowe: So, it's an interesting thing, that the vaccine protects, but we don't give it to people because it's just a rare disease in the United States. I can't imagine that anybody would die from rabies routinely anymore because of that.

Dr. Mitek: Right. And it's one of those viruses where we can't diagnose it off a blood test, which we're so used to that, or off of a nasal swab, like a lot of people are comfortable with now with COVID. Why do you have to be dead before we can officially diagnose you with rabies? That defeats the purpose of diagnosis before treatment, right?

Dr. Lowe: Well, unless you're a pathologist.

Dr. Mitek: [LAUGHS]

Dr. Lowe: It's because the virus only lives in nervous tissue and neural tissue. It lives in brain cells, that's where it really likes to live. And so, it's pretty hard to sample the brain when you're alive. Well, you can sample the brain if you're alive, but then you're not alive anymore. So, that's one of the challenges. And we deal with that a lot with infectious diseases, can we get a sample that actually reflects the infectious status of the host, or in our case, the animal? We deal a lot with that with cow diseases, Johne's disease, the virus is hidden in mycoplasma in pigs.

Dr. Mitek: Johnny's disease?

Dr. Lowe: Johnny's disease, yes. But there's a lot of diseases like that. And then, the big other disease we worry about that you have to actually have brain tissue - Johne's disease is a disease of the intestine, but it's in the lymph nodes, and without actually having the intestine out, it's kind of hard to get samples, and the samples aren't very good. But the other big one we deal with, which very much has the same problem as rabies and infects brain tissue, is the transmissible spongiform encephalopathy, so, mad cow disease. The one everyone would know about is BSE, but then we have a similar disease in sheep called scrapie, and in deer and sheep called chronic wasting disease, CWD. So, all of those are TSEs. They're prions, however you pronounce that word, so they're not a virus. But again, it's a disease that's only in the brain, and the only way I can diagnose that... As advanced as we have gotten with all of our fancy tests, if I can't get the sample out of the creature and get it to the lab, I still can't get a diagnosis. And unfortunately, rabies, the TSEs, mad cow, the only way we can diagnose that is post-mortality. And so, that really presents some significant challenges for control, because I can't test living populations to know where the virus is at.

Dr. Mitek: Right, and it seems like the takeaway from this case is that it's, unfortunately, a good reminder that if you are ever exposed to a bat or bitten by a bat, if you can't catch the bat and send it off to be tested and show it doesn't have rabies, you probably are going to have to undergo the post-exposure series, right?

Dr. Lowe: Yeah.

Dr. Mitek: Because once you're symptomatic... I didn't remember much from virology, but once you're symptomatic with rabies, it's kind of like a no bueno, you're probably not going to make it. And then, I remember, the other thing that was interesting was that the closer the bite is to the brain, the more quickly you become symptomatic, the more quickly you die.

Dr. Lowe: Yeah, less time of transmission to move up the nerves into the brain.

Dr. Mitek: It has to crawl into the...

Dr. Lowe: Into the noggin, yep.

Dr. Mitek: Very interesting.

Dr. Lowe: So, the interesting bit about rabies to me - so, I said this is completely preventable in the U.S. That's not the case in the rest of the world.

Dr. Mitek: I think I read something that there are over 55,000 rabies deaths a year. Of course, the vast majority of those happen not in the United States. But it's still a really significant disease outside of our country, which probably most of us don't think about.

Dr. Lowe: No, and it's because they don't have good dog vaccination programs. In a lot of parts of the world, there's a lot of feral dogs, those dogs aren't vaccinated. Domestic dogs, I think, globally are pretty well vaccinated. But there are a lot of unowned or feral-type dogs in a lot of parts of the world, and those dogs are not vaccinated - and they're not here in the U.S., but we just tend not to have as many. And so, that unvaccinated population really serves as a reservoir of rabies virus. And so, there's continuous circulation of rabies in those areas. And so, if you get dog bites with people, you end up with, again, rabies infections. It's one of the, we'll call it modern marvels of the West - we don't see it in Western Europe, we don't see it here in the U.S., Canada, Mexico. But the rest of the world, that becomes a significant problem as those dog populations are unvaccinated, and now they can transmit it to each other, and you end up with a long-term reservoir of disease.

Dr. Mitek: And you were telling me a little while ago about potentially dogs coming into the country.

Dr. Lowe: Oh, yeah, back to African swine fever.

Dr. Mitek: Yes.

Dr. Lowe: Some things you stumble across in life, right? Then you start to connect the dots. So, we're very worried about African swine fever. And if you've seen any of the news, it's rampant, endemic in Eastern Europe and in China. And the big problem with ASF is that it's terminal for pigs, but because it's a regulated disease, we can't export it. So if you have ASF, you probably can't export pig meat out of this country.

Dr. Mitek: Can you still eat it?

Dr. Lowe: Yeah, it's actually perfectly fine to eat. But one of the interesting bits about African swine fever is is that it's the muscle that carries the virus. And so, the meat itself can be contaminated, it can be a source of transmission. So, we work really hard not to let those pigs into the food supply chain, not because it's not safe, but because we don't want to transmit the virus anymore, because the pig muscle itself can transmit it. And that's what we see happening in other parts of the world. They butcher a pig that's infected, they have sausage, the virus lives in even dry sausage for long periods of time, they go to their friends in the neighboring village, they share the sausage, the sausage gets thrown out, and it gets eaten by wild pigs in the area, and they transmit the virus to the next spot. So, this meat transmission with ASF is a big deal. That's neither here nor there for the point of this podcast.

However, as we've been working on African swine fever as a swine community, we've had some really, really interesting conversations. Now, meat can carry it, and in a lot of foreign countries, dogs would be eating meat, not dog food. They would eat raw meat or carcasses as animals die. Well, come to find out, there's a huge number of dogs imported into this country as "rescue dogs", and put that in quotes. There are organizations who are quote-unquote "rescuing" dogs from China and Eastern Europe and other places and importing them into this country. So, that turned out to be a huge issue for us because animals that have eaten infected meat can actually shed ASF for a long period of time, which means that the dog could be infectious for African swine fever and potentially infect pigs if it gets around pigs. And you say, "Well, jiminy, Jim, they're not importing the dogs to the pig farm," which is true.

Dr. Mitek: Yes, that's exactly what was in my brain.

Dr. Lowe: Except, pot-bellied pigs are susceptible.

Dr. Mitek: That's your favorite type of pig, though!

Dr. Lowe: We're not talking about that here.

Dr. Mitek: You just want me to anesthetize them so you can paint their nails purple. [LAUGHS]

Dr. Lowe: That's never happened. So, these pot-bellied pigs, if you go back and look at rescue organizations, there's a lot of pot-bellied pigs in rescue organizations. These safe rescue organizations are taking in high numbers of foreign dogs. It doesn't matter if we have a pot-bellied pig infected or a commercial pig infected in the United States; it has the same consequences for exports, for business continuity for the U.S. pig production.

Dr. Mitek: You have to go back for a second and help me make the connection between if a pot-bellied pig gets ASF, and what that means-

Dr. Lowe: Any detection of African swine fever in the United States means that they will close our borders to exports.

Dr. Mitek: Even if it's in a pot-bellied pig?

Dr. Lowe: They don't care. It's in a pig. So, until we can prove that it's eradicated per OIE - the World Organization for Animal Health, which is the animal version of the WHO - per the trade rules that we've all agreed to, positive countries can't export. So, a positive test equals-

Dr. Mitek: No export.

Dr. Lowe: No export.

Dr. Mitek: For the entire...

Dr. Lowe: The entire country.

Dr. Mitek: And for how long?

Dr. Lowe: Until you prove it's eradicated.

Dr. Mitek: How do you prove it's eradicated?

Dr. Lowe: You have to have no positive tests, and there's a whole bunch of... we could have a four-hour podcast on what we're doing to prepare.

Dr. Mitek: As long as I can have my almond milk latte, or, like, three, during it.

Dr. Lowe: It might take six.

Dr. Mitek: [LAUGHS]

Dr. Lowe: But, you get the point, that we have all these goofy things. And so, as we've been talking in our state here in Illinois, we're just having a chat with them, he said, "You know how many dogs come into Chicago that are rescued?"

Dr. Mitek: O’Hare.

Dr. Lowe: O’Hare. We import animals into O’Hare  all the time, that's one of the international import locations. But when a horse shows up, there's a quarantine procedure for that horse, and it goes to a quarantine barn, and we know where the horse is at. If a pig shows up in Chicago, which we don't do, we do import some cows, they go to a quarantine facility and we know where they're at. These dogs are showing up in Minnesota, they were going to quarantine them in Minnesota. That's not how...

Dr. Mitek: You control infectious disease.

Dr. Lowe: And it's not how animal quarantine rules work. Right? They can't cross state lines. The states still have a lot of purview over that. USDA has purview if this is an international importation. So, that's what started raising the conversation. So, this is rolling around in my head. First of all, I didn't realize how many thousands - it's in the thousands of dogs per year coming in, from places like China. A lot of ASF. And then, here in the last couple of weeks, I think right before the human case of rabies, there was a group of dogs imported - and I forget which country came from - there was a positive rabies dog in that importation. And so then they ended up having to euthanize the whole importation - back to your question about how do you test for this. Couldn't test the rest of them. They'd all been exposed. Nobody had any idea what the vaccination status was on these dogs.

And so, you start looking at these models, right? And you say, okay, rabies isn't a big deal here in the U.S., but we've got this other whole bit of exposure. This is the fascinating part of infectious disease for me. There's just stuff going on, and how do these connections fit together, and how to dogs from China fit into ASF transmission risk? But then you stop and you look at this, and you say, oof, we have a way bigger issue than African swine fever, which is a bit of a pig problem. But, if dogs are being brought in, and they're rabies-positive, and we don't know their vaccine status... God, you'd hate to see one of those go to some family, right, and turn up rabies positive a week later, and...

Dr. Mitek: That's what I was going to say - I think we've all done veterinary medicine long enough where we've all had cases that have ended up being rabies-positive, that we didn't expect we were going to have rabies, or rabies suspects. And the risks to human personnel, right? I haven't personally had one, but of course, everybody has a friend of a friend who had a puppy dropped off at the clinic, and it had neurologic signs, and everybody loves on the puppy, and then oh my gosh it had seizure, and you find out it was rabies-positive, and it wasn't vaccinated or whatever. But I would imagine all those people that handled that dog at O'Hare - or, like you said, if it goes to a family - they're all going to have to have that post-exposure sequence, which isn't fun and isn't cheap.

Dr. Lowe: No. And think about it, as you say, the people over at O’Hare, that includes the baggage handlers, and... So, there's just always a lot of stuff that happens that we don't know about. And I think, this whole rabies case in the Chicagoland area is just a good reminder, right, that, A, listening to medical advice, when they say, "Maybe you should do this," is a good idea. And two, for me, if you think something's gone away, i.e. rabies - rabies is just not on my radar screen as a public health concern. I'm worried about influenza from a public health concern, I'm not worried about rabies. But, you start putting the pieces back together, maybe it's not as gone as we would like to think it is, because the world's pretty interconnected, and what goes on in China or what goes on in Lithuania might matter.

Dr. Mitek: Right. And I think we should mention that we're on the... one, two... I can count... we're on the second floor of the Veterinary College. And on the first floor is our diagnostic lab, which does a lot of rabies testing, from what I understand. So, it's still out there in the world, right? Even in our community, I'm sure there's a bat out there somewhere with rabies, right?

Dr. Lowe: Yeah. I think that's it - as we start to wrap this up, right, infectious disease is really cool because it's always different. It's always something new, and when you think you know, you don't.

Dr. Mitek: Mother nature always outsmarts us. Mother virus always outsmarts us.

Dr. Lowe: Yeah, I think that's the other take-home. Every time we turn around, when you think you've got it knocked, you let your guard down. Because rabies, theoretically, I was pretty convinced mentally, "Ah, this one's solved. Don't need to worry about it." And yet, here we go. And so cannot forget that old things rear back if we don't maintain our vigilance.

Dr. Mitek: That is good advice. So, anybody out there, don't play with wild bats. If you get bit by one, or I guess really any wild mammal, go talk to your doctor.

Dr. Lowe: That's correct.

Dr. Mitek: And I think with that, that is wrap. Thank you Dr. Lowe.

Dr. Lowe: Thank you, Dr. Mitek.

Dr. Mitek: Thanks for joining us. We hope you enjoyed listening, and we'd love to hear from you, too. Find us on Twitter. Our handle is @TheRoundBarn1. We may even share your comments on our next show. Please subscribe and tell your friends about the show. It's available on iTunes or the podcatcher of your choice. One last thing - we also offer a wide range of learning opportunities for folks who work with livestock and veterinarians, too. You can learn more at online.vetmed.illinois.edu. See you soon!

Have Questions?