Episode 53: Hantavirus: The Facts

Dr. Emily Landon of the University of Chicago joins the show to explain everything you must know about the Hantavirus - should we be concerned? What to do? What not to do? Is this another COVID?
Get the facts right here, and please share, subscribe, and join the conversation.

Transcript

SPEAKER_01 0:01

Welcome to the Healthcare Unfiltered Express, where I conduct short video interviews, bad, relevant, and timely information that you cannot miss. Sit back and enjoy the show. Well, she's back, Dr. Emily Landon on Healthcare Unfiltered Um Express. Uh Emily, thank you so much for coming on. I know how challenging your schedule is, so it does not go unnoticed. We really wanted to cover really quick the Hunter virus because everybody's talking about it. And want to always separate the signal from noise and the myths from facts to make sure that people who are listening and viewing this show really get the information that uh are accurate. So let's start. First of all, I want to make sure people know where you are. Just tell us a bit where you practice.

SPEAKER_00 0:47

Hi, I'm uh it's good to see you. Good to be back. Um, I'm Emily Landon. I'm the hospital epidemiologist and adult um infectious diseases expert at the University of Chicago Medicine. And I've been here for a very long time now.

SPEAKER_01 1:02

I like that. Let's just keep it at that.

SPEAKER_00 1:04

Yeah.

SPEAKER_01 1:05

So, huntavirus, what is it?

SPEAKER_00 1:07

Hontavirus is a technically, it falls in the family of hemorrhagic fever viruses, which makes it sound even more terrifying, right? Um, but it's a virus that's often spread, almost exclusively spread, from rodents to humans. And it's actually one of the few things you can get from a rodent that's actually dangerous. So if you want to be afraid of mice and rats, you can use the hontavirus as your reason. Um, it it is excreted by rodents and and and not just mice, but also rats and voles and other rodents in their urine and in their saliva and in their feces. And oftentimes what happens is that those get dried in the environment. And then when people go to clean out an old building or something like that, or they are hiking or in the in the forest and they're walking through an area or they having to walk through an old um nest or something, they can sort of um aerosolize that dried um urine or feces, and that can result in you breathing it in and then developing hontavirus. But hontavirus is a huge family of viruses that includes two main sort of arms of infections. And some are more severe, some are less severe. In Europe and Asia, the hantaviruses that live there are more likely to cause hemorrhagic fever, which really just means coagulation disruption and um and problems with the kidneys. It makes your kidney tubules very leaky because these are endothelium-focused viruses. They go to the inside of blood vessels. And then in the Americas, the hantaviruses that have sort of become endemic here in our rodent populations are more likely to cause problems with pulmonary vasculature. And so you result with really leaky, if you have the serious version of it, you get really leaky pulmonary vessels, and then you sort of end up flooding your lungs with fluid, and then your heart kind of shuts down, and we call that hantavirus cardiopulmonary syndrome. And the important thing to know about this virus is that there is only one virus of the whole family of a dozen or more hantaviruses, there's only one that actually transmits between from person to person. All the other viruses are limited to just you have to be exposed to a rodent.

SPEAKER_01 3:24

I see. Like in the cruise, this was the human to human. Tell us about the cruise.

SPEAKER_00 3:31

Yeah, so that's Andes virus. And the Andes virus is a predominant, is the predominant cause of hontivirus cardiopulmonary syndrome in South America, Argentina, Chile, some cases in Brazil. And the thing to know about this is that it's been around for a really long time and it actually hasn't changed very much. The sequences show that these viruses have remained really stable over many, many decades, and it's caused multiple outbreaks that have resulted in person-to-person transmission across Argentina, Chile, South America over the years. And many of those, and all of them, have stopped easily with um with public basic public health measures. The key to hontavirus that spreads from person to person is that it's difficult to make a diagnosis of hontavirus. This is because in the first five days of illness, it looks like the flu or food poisoning. The one in the in Central America tends to be more, um, have more GI symptoms early on. And people just, you just don't recognize that it's anything really bad. And then only a subset of people go on to have this hantavirus cardiopulmonary syndrome. And then they often die really quickly if they're in a rural, but these obviously these happen more in rural areas, and then you can die before anybody's able to make a diagnosis. So it might take a couple of cases for them to even be able to make the diagnosis of hantivirus. And then when they do and they realize that it's Andy's virus, they're like, oh no, we've got a cluster. And then they implement these basic control measures and all the infections stop. But it's that time period before the diagnosis can be easily made in these sort of underserved or rural medical systems, where that's the opportunity for the virus to spread. Because once you start separating people from that have been exposed from other people, you know, through quarantine and asking people to wear masks, it's really not hard to stop the transmission of this virus.

SPEAKER_01 5:23

How do you test for it? What test do you do to check if you have the HANTA virus if you start developing these symptoms?

SPEAKER_00 5:29

So the most people, because these cases are usually just sporadic, we don't test anyone unless they um are having cardiopulmonary syndrome. And then you need to do the right things before you're gonna get your test back. So you have to be suspicious of it and figure it out. But the the testing is is complicated. We can get serologies, which is just, you know, getting antibody testing. And those are reliable actually from the start of um of symptoms. They're usually you have a pretty significant IgM spike. So those can be used then. But I think um now we're sort of switching over to RTPCR, of course, because this I mean it's an RNA virus, so you need RTPCR, but same difference, it's PCR. And those are really good, except the main send-out test that you would get in the United States, you send it out to Quest, has a really high false positive rate. And so you often need confirmation by the CDC in the United States. And so, and there's you know, there's laboratories that can do that confirmation in South America, but you can see how this gets it's a little tricky to make the first diagnosis of a cluster. But once you know that you have a cluster, it's pretty simple to stop the transmission.

SPEAKER_01 6:36

The the when I was researching this, they're saying mortality rate is 30%. Is that is that true? So one out of three people die from this.

SPEAKER_00 6:45

So I think that's probably high. So we know that one of three people that we know have hontavirus die of hontavirus. But if you can imagine, there are probably, oh, we also know that in these clusters of infection for ondues virus, for example, that a number of people don't go on to have hontavirus cardiopulmonary syndrome. And so the 30% number actually comes from um from those clusters where a number of the patients never go on to get very sick, but the ones who go on to get very sick often die. Now, with ECMO, you can save a lot of people. With aggressive early, so the thing you have to know is that when people come in with what looks like, I mean, as a physician, you understand, and the and the medical people that are listening are gonna follow me a little bit better here. I'm gonna get in the weeds for just a second. The you a patient comes in with severe respiratory distress and they've got infiltrates on their chest x-ray, you automatically think they have pneumonia because they've been febrile for five days. You flood them with antibiotics and with fluids, right? Because that's what you do. That's the wrong thing to do for hontavirus. It will absolutely kill them. And so we know that when we don't suspect hontavirus, that leads to a higher mortality rate. When you do suspect hontavirus and you know that's what it is, you don't flood them with fluid, you're probably still going to give them antibiotics. You immediately get them like cannulated for ECMO and you don't intubate them until you start the ECMO. There's a number of things you can do to improve the survival. But again, it all comes down to that likelihood of the diagnosis. In the United States, we're pretty like ID docs like me, think about hontivirus all the time when someone comes in with bilateral pneumonia that is um crashing and burning really quickly. And it's our job to alert the critical care docs. This may be the situation, maybe hold off on that fluid, you know, figure it out, right? But um that's because we mostly have sporadic cases. You can imagine on a cruise ship where they don't have any imaging, where you have very limited testing and where everybody's in really close contact. That's a really small ship. I mean, let's think this through. There's really only one dining room, one gathering place, like lounge area, one yeah. I mean, so everybody's together and it's like many weeks on end, and you have no real imaging, no real hemodynamic monitoring that might tip you off. You're not gonna be able to get things like LDH and other tests that we would we would get that would say, Oh, this looks like Honda virus, you know, you're not gonna get any of that on a cruise ship. And so you um you can see how it's missed for such a long time.

SPEAKER_01 9:16

So, what's the treatment if you diagnose it? And if you suspect it and you believe it is, um, well, first of all, do you have to have confirmation of the diagnosis to start treatment, whatever that is, or there's no specific treatment, so it's all supportive.

SPEAKER_00 9:30

You need to manage the physiology. If you can manage the physiology, patients do much, much better. And so you have to suspect the diagnosis. For the in the United States, we have something called C nombre virus, which is around the four corners. It's also present in other parts of the United States. There have been a handful of cases in Illinois over the years. There's one suspect case right now in Winnebago County, although I don't know if that'll be actually a real case or not. Um, but you have to sort of know you have to suspect it early and manage the physiology. There are some medications, some antivirals that have had some success when they are used before or at the very beginning of symptoms. But vavapyrivir is not available in the United States. It's not been approved by the FDA, and so we don't really have access to that here. And it's not sure, it's not clear that it actually does much of anything. You have to kind of start it before the patient gets viremic in order to see any benefit whatsoever. And then ribovirine has been used with some success in some cases of the more European Asian version, which is the hemorrhagic fever with renal syndrome. There is some utility to using ribovirine, but it's ribovirine's been proven to not work in hontivirus cardiopulmonary syndrome. So I I there's really not anything that we can use. So as you could imagine, you don't need to confirm the diagnosis. You just need to think of it and manage the strategy.

SPEAKER_01 10:52

But as you could imagine, everybody is nervous. Is this COVID? What are we gonna do? Masks, lockdown, and so on, and all of these things. So help us understand how this compares to the COVID uh situation.

SPEAKER_00 11:04

First of all, the very first introduction of COVID into the human population in Wuhan, China in 2019 resulted in a global pandemic. I want to remind everyone that this virus has been around for probably centuries. Um, it hasn't changed at all in decades. There have been multiple introductions in South America in rural areas where there's been spread and it's been stopped easily without lockdowns or even widespread mask usage or quarantine. It's really about targeting the close contacts of those individuals and keeping them away from other people until you see whether or not they develop symptoms. And that can take a long time and it's really annoying for those people because the incubation period is like six, seven weeks. But it isn't, um, this is not the end of the world. Now, I do want to caution that I have heard there are people talking about how much a lot of people are saying we don't need to worry about this because you need really prolonged close contact. I think that may be a little bit disingenuous and maybe a little bit misleading the way some people are putting it. We know that in the situations where there's pretty good ventilation, it doesn't spread to very many people. A person who walks into a you know sort of average room with COVID can maybe give it to eight other people if they're not immune, right? If you have a person with hontavirus walk into that room when they're symptomatic, they might spread it to one person. And so the overall risk, the transmissibility is less efficient. But we do know that in some settings, with some patients, remember, transmission depends on three factors patient factors, like how bureamic, how much they're shedding, and then the uh the sort of number of people they have contact with and the setting in which they're contacting, and then the viral factors. Now, the viral factors for Auntie's virus haven't changed. Some patients might be more likely to superspread than others, but the setting, the number of people they have contact with, the amount of contact they accumulate while they're sick and the ventilation in those spaces does play a big role. There were some cases in 2018-2019 in um Argentina where people got sick after, you know, just having, you know, being at the same birthday party with someone for 90 minutes. And that, you know, isn't quite the same. So I think that might make people really worried. But it's important to note that these people who've been exposed, there's no reason why they would ever have 90 minutes of close contact with someone while they're in this incubation period in case they get sick. That's it's pretty easy to prevent that. It might be difficult to prevent them if they're not in, you know, locked, if the the the contacts aren't in, you know, lockdown quarantine. You might think, well, what if I walk past them in the hallway or something? You're not gonna get it that way. That's not how this disease works. But it is not, I mean, you don't have to be necessarily be like a sexual partner, a bed partner with someone in order to get a Honda virus. So I I think there's like sort of a middle road.

SPEAKER_01 13:59

This is very helpful. I think a lot of people who are listening and viewing this are gonna take a deep breath and they're gonna feel much more comfortable after they heard you. Is there anything else that we should tell uh people that I forgot to ask you about?

SPEAKER_00 14:10

Let me think about that for a second. I I think you covered everything that's really important here. Um I would say this is not gonna be a COVID situation, but it is a really serious disease that does threaten the lives of individuals who are exposed to this. It's it's not trivial. It is a big deal for these people. And I feel my heart goes out to all the people who are in isolation or in quarantine, we would say right now, waiting to get these test results. It's not an easy situation to be in, but I think I wish Yeah, I mean, I wish I wish our CDC was a little faster at responding. I wish the CDC had more capacity to do more confirmatory testing. But um, but you know, I think these individuals are going to be monitored really closely and are gonna be taken care of.

SPEAKER_01 14:55

Dr. Emily Landon from the University of Chicago. Thank you so much for joining me on Healthcare Unfiltered Express.

SPEAKER_00 15:01

Happy to be here. Thanks for having me.

SPEAKER_01 15:03

Thank you for listening to this edition of Healthcare Unfiltered Express. Until next time, take care.