The Fungus Among Us

ROBERT JOHNSON:
This is Public Health Review. I'm Robert Johnson.

On this episode: fungal diseases cost the nation $7 billion in direct healthcare expenses each year. Our focus is on three of the worst offenders.

DR. TOM CHILLER:
I want to advocate that the medical community think fungus. I want to advocate that we in the diagnostic field get better tests so that we have better fungal diagnostic tests out there. Many of our tests are decades-old, and we need to develop new technologies to help diagnose people rapidly so that we can manage them more rapidly. And that's going to be the way to save lives from fungal infections.

KRISTEN EHRESMANN:
We can't eliminate environmental exposures, we can't get rid of soil—it's an important part of our existence—but what we can do is we can make people aware of the fact that this is a risk, and we can make sure that providers are aware of the fact that these diseases are occurring—you know, where they're happening and who is at greatest risk—so they can incorporate that into their patient evaluations.

JOHNSON:
Welcome to Public Health Review, a podcast brought to you by the Association of State and Territorial Health Officials. With each episode, we explore what health departments are doing to tackle the most pressing public health issues facing our states and territories.

The old saying, "There's a fungus among us," is not far from the truth, but the fact is most fungi are relatively harmless, some are helpful, and a few are used in cooking. Those, however, are not the fungi we are talking about today. We're taking a look at three fungi and the diseases they cause: valley fever, histoplasmosis, and blastomycosis.

Joining us to discuss these fungal diseases is Kristen Ehresmann, the director of infectious disease epidemiology, prevention, and control at the Minnesota Department of Health.

But first, we get the national view from Dr. Tom Chiller, the chief of the mycotic diseases branch at the Centers for Disease Control and Prevention in Atlanta.

CHILLER:
There are fungal diseases that can be invasive—in other words, they can get in to our bodies either via the lung or via some other route and can get into our bloodstream, get into our organs, and really cause serious damage.

For the most part, a lot of these fungal diseases are what we call opportunists; so, they take advantage of a patient or a person that is immunocompromised, or that may be taking medicines that suppress that person's immunity or their ability to defend against these organisms, and they are then at risk. And those people can get very serious fungal infections if exposed to them and inhaling them under the right conditions.

For the most part, healthy people are not at high risk for fungal infections, but there are a few that we'll talk about later that actually can be risky for healthy individuals.

And so, again, it would be important for the medical community to be thinking fungus when they are evaluating their patients.

JOHNSON:
Is that something not on the checklist today? Would you like to see more physicians going through that list when they see someone in their office?

CHILLER:
You know, I do think that they are often forgotten about in the initial assessment, and what we're trying to advocate is more about thinking about fungus initially.

What we've found in some of our work with colleagues across state and local health departments and in hospitals and clinics is that oftentimes if a fungal diagnosis is not thought about from the beginning, then you may experience a patient getting multiple rounds of antibacterials that are useless in that particular infection to try to treat something that is actually not there.

So, we do believe, obviously, that these are not exceedingly common infections for the most part, but if you don't think about them up front, we run the risk of putting our patients at risk of other diseases or other adverse effects due to the medicines we're giving them and not diagnosing the fungal infection early.

JOHNSON:
How big of a problem are these infections, these diseases, caused by some of these less desirable fungi?

CHILLER:
That's a great question, and we ask that always in public health as we try to assess and prioritize what diseases we tackle.

You know, unfortunately for fungal diseases specifically, we don't have very good surveillance. There aren't national surveillance systems for many—if not all of, almost all of—the fungal diseases. And, therefore, we don't have good estimates yet about how they rank or how they compare.

But certainly, in certain parts of the country where there may be a certain fungal disease like Valley fever, which we'll talk about probably in a bit, we know that they can cause a tremendous amount of infection in a particular community or in a particular area where they are highly endemic in that geography. So, they can be a major problem in certain areas.

And so, I think, unfortunately, it depends. I hate that answer, but it depends a little bit. And that's one of the reasons why we want you to think fungus when you're thinking about a patient who has a potential pneumonia or some other symptom manifestation of a disease when you're looking at your patients with differential diagnoses.

JOHNSON:
Why is the surveillance spotty in this area of medicine?

CHILLER:
One of the issues with public health surveillance is, again, we have a lot of competing priorities and diseases, and doing surveillance is a very time-consuming effort for all involved. And so, I think that we have been prioritizing diseases that are clearly more common in general. And then, when we want to add another disease on to do surveillance, it's a big lift, it's a lot of work.

And on top of that, fungal diseases, unfortunately, are challenging to diagnose. We don't have all the great tools that we often have for bacteria or even viruses to make the diagnosis.

So, there are some challenges in actually getting the diagnosis correct. There are some challenges in getting that on the list of conditions that we do surveillance for.

I think the good news is, is that there is more effort with state health departments and the medical community to see these diseases as important and to figure out how we can do better in doing surveillance for them in the future. But we still need to work on that.

JOHNSON:
Nevertheless, some states actually do keep track.

CHILLER:
Absolutely. And you know, one of the older diseases that's been under surveillance is actually Valley fever—the long name of coccidioidomycosis, it's sort of a mouthful, so we often just refer to it as Valley fever—and I think around 25, 27 states routinely report that disease, which then comes into the CDC where we keep track and have done that for several decades.

So, for example, we have some idea about valley fever and about the amount of disease that's occurring across the U.S.

JOHNSON:
Let's talk about some of those worst offenders, if you will. Valley fever is on the list.

CHILLER:
Yeah, valley fever is on the list. And part of the reason why it's all on that list is that it presents in a very generic way.

So, someone has like a flu-like illness, it could present like a pneumonia—or a walking pneumonia, as we call them—and so it's a mimicker. It looks like a lot of these other bacterial diseases that can cause symptoms, even flu-likes or viral diseases that cause the flu, influenza.

And yet, it lasts a lot longer and it can take people out of work longer. And it is often, therefore, missed because it looks like a lot of the common respiratory disease is that people see. So, it can be a real challenge in that regard to diagnose. And if you're not thinking of it up front, then you're not diagnosing it, and then you're not managing that patient appropriately.

And the other thing about Valley fever that is challenging is that this is not just one of those opportunistic infections that I talked about earlier, this is actually an infection that can get anybody. It can get healthy people as well. And it probably is a matter of how many spores you inhale, where you are in that particular day, but it's not just those with compromised immune systems or who are taking some medicine—it can be healthy people that get this disease. And, therefore, it can be challenging, again, to manage and to identify.

JOHNSON:
It's mostly dust-born, correct?

CHILLER:
Yeah. And this is a disease that lives in the soil. And so, it's in dusty areas or areas where construction is going on, it's been associated with outbreaks—recently, had several outbreaks on solar farms, probably because of the workers working in a dusty environment to set up the solar panels—you know, we've had outbreaks throughout the years associated with, essentially, digging in dirt.

So, yes, it is a dust-associated or airborne infection and generally associated with dirt.

JOHNSON:
Also on the list is one known as histoplasmosis. Talk about that one and what is unique in that case.

CHILLER:
So, histoplasmosis is another fungi that is what we call dimorphic—and so, in other words, having two faces—and Valley fever that we just talked about is also a dimorphic fungi. What that means is that it exists in one form in the environment, in the soil, in the dirt like I just talked about.

When it infects a person, it changes into another form in the human body. And why is that? Well, it's a temperature differential. So, you have sort of an outdoor temperature, and obviously the human body temperature, which is 98.6, and then the, of course, much lower temperature, the infectious forms are in that lower temperature.

And so, the good news is unlike some of our bacterial colleagues—like tuberculosis, for example—that's a microbacterium that we know is highly contagious person-to-person, these dimorphic fungi are not. So, once they are in the human, you are not contagious to somebody else.

Histoplasmosis, like Valley fever, is also found in the soil, but it's interestingly also associated with bats, because it can actually go through the digestive system of bats and is found in their guano. And also associated with bird guano—bird poop—right, because it's a very nitrogen rich environment and so, the fungus is happy growing in those areas. So, you often find it, you know, associated with various bird roosts or bat caves. And, in fact, one of the classic ways to get histoplasmosis is people exploring caves and they report, "Oh yeah, the large amount of bat activity, a large amount of bat guano," and then they can, unfortunately, get histoplasmosis.

Like Valley fever, histo can present again with a very generic, long infection type of presentation in patients—so, they can look like they have a slight pneumonia, like a flu-like illness. And this fungus, again, is geographically located mainly in sort of the middle part of the United States, but it's been described globally. So, I think we don't really know all the places where histoplasmosis is.

But again, it's another one of these fungal infections that can present very similar to many of our bacterial and viral pneumonia-like looks. And so, it's important again, to be thinking about histoplasmosis when you see these kinds of patients.

JOHNSON:
Let's talk about the final one: blastomycosis.

CHILLER:
Blastomycosis is the third one on this list of, again, these dimorphic fungi, or fungi with two faces. They can, again, cause a very generic respiratory disease picture, just like we've been describing. But, again, it has a geographic predilection to more of the northern and northeastern part of the United States—although it can also go down into the South—and this is a unique fungus because geographically it does appear to be mainly North American—so, we find in the United States, we find it in Canada.

Although, once again, as I described, there are all of these fungi out there that we haven't identified. We are now identifying newer species of this particular organism, even now, in South Africa and in other parts of the world. When you look for fungi, you know they're out there. And so, my question then always is, "Is this going to be a potential pathogen for humans?"

Blastomycosis is another one of these fungi that can mimic pneumonia can look very general, again. And so, it's another one of the three diseases we want people to be on the lookout for if they see a patient who presents with a respiratory illness.

JOHNSON:
Are you uneasy about the fact that we really don't know how much of this is going on in the country due to the lack of surveillance?

CHILLER:
You know, I'm always uneasy about lack of surveillance data when I'm trying to help clinicians and the public and others make decisions about, you know, healthcare and about ongoing infections, et cetera, you know, which is why I think we're taking an approach of trying to understand better these geographic diseases—which is the endemic fungi, they're called endemic but I like to think of them more as the geographic fungal infections—so that we can educate those providers and the public in those areas where they exist so that they look for them and they think about them when they're diagnosing their patients.

But surveillance dramatically helps us understand those specific geographies. So, I would definitely like to see more surveillance for these organisms. That being said, those of us in public health would like to see more surveillance for everything, and we know that's impossible. We have to prioritize and we have to realize we have limited resources to do these kinds of things.

I want to advocate that the medical community think fungus. I want to advocate that we in the diagnostic field get better tests so that we have better fungal diagnostic tests out there. Many of our tests are decades-old, and we need to develop new technologies to help diagnose people rapidly so that we can manage them more rapidly. And that's going to be the way to save lives from fungal infections.

JOHNSON:
I know there's a test for Valley fever—I had it when I entered high school in Safford, Arizona in 1979. Are there diagnostic tests for these other diseases we've talked about?

CHILLER:
Yeah, you're absolutely right. Valley fever, there is a test. There are some new kids on the block for Valley fever, which is great after many years of not having them. Some more rapid tests are becoming available, that's great.

Histoplasmosis has also some very good tests as well that are out there, and there are some improvements in that field.

Blastomycosis, unfortunately, is lagging a bit behind—we still don't have great testing for blasto. Some of this is knowledge of the disease. Thinking about it, you can send the test, but even if it's negative and the patient really has consistent symptoms, you may need to use your clinical judgment to know whether they have blasto or not. But there's still work to be done in that area, for sure.

JOHNSON:
We're talking about this because September 23rd is designated Fungal Disease Awareness Week.

Tell us what's on the agenda as it relates to bringing people up to speed on what we're dealing with here and how to attack it.

CHILLER:
Yeah. So, a lot of what we talked about today is really the heart of what we're going to be talking about this year at Fungal Disease Awareness Week during September. We really want to focus on the geographic fungi: valley fever, or coccidioidomycosis; histoplasmosis; and blastomycosis; as well as some of the other dimorphic fungi.

We're also going to be focusing some of the time and attention to anti-microbial resistance and the emerging organism called Candida auris, which has been in the news recently, which is a multi-drug resistant fungi that's also emerging in some of our healthcare situations.

And so, we'll be focusing the week talking about those various things in various formats and platforms and have reached out to many of our partners out there so they can get the word out as well.

JOHNSON:
Minnesota is one of several states taking a look at histoplasmosis in the Ohio and Mississippi river valleys.

Here's Kristen Ehresmann, director of the infectious disease, epidemiology, prevention and control for the Minnesota Department of Health.

EHRESMANN:
Histoplasmosis is a fungal infection. It's typically acquired through inhalation of spores that are found in soil that have been contaminated with a fungus. And as you mentioned, although Valley fever may be more well-known, histoplasmosis is actually the most common mycosis in the United States—so, the most common infection caused by fungus.

JOHNSON:
How does it get it start? Where does it live? What should we be on the lookout for?

EHRESMANN:
The spores for histoplasmosis are found generally in soil, so when people are working in the soil, if there's been construction. They can also be found in bird and bat droppings.

So, those are all places where people can come in contact with this fungus.

JOHNSON:
And then it gets stirred up, becomes airborne. That's how you get it into your system?

EHRESMANN:
Right. So, what happens is either, you know, there's construction going on and, so, that may cause the fungus to become aerosolized. It may be just that you're doing your gardening work, that that will aerosolize the fungus. Or sometimes, if bird and bat droppings, if they are a little bit dry or there's movement of the parts of the dropping, that will aerosolize.

JOHNSON:
Is everyone at risk for getting this condition as a result of the fungus in the air?

Or are there specific groups that need to really be careful around these areas?

EHRESMANN:
Well, I think everyone is at risk of developing an infection, but what is not an equal opportunity is who would be more likely to develop more severe infections.

So, many of infections—in fact, there's some estimates that suggest that—for healthy individuals, maybe 90% of people, they could be infected, but have an asymptomatic or very, very mild infection.

But for some individuals like those who are immunocompromised or have other underlying health conditions, they can actually develop very severe symptoms.

JOHNSON:
What do those symptoms look like?

EHRESMANN:
The most common symptoms typically include fever, cough, difficulty, breathing, chest pain, and headache, and those symptoms can progress to a very severe pulmonary illness.

And then if someone is immunocompromised, they can have disseminated disease. So, the disease goes well beyond their lungs, to liver, spleen, GI tract, bone marrow, that type of thing. You can have severe pulmonary disease, as well as disseminated.

JOHNSON:
This actually sounds fairly serious.

EHRESMANN:
It actually can be serious, and that's part of the reason that state health departments—particularly those that are right along sort of the concerning area, which is the Ohio and the Mississippi river valleys—are really looking at what is happening related to the histoplasmosis in their jurisdictions.

JOHNSON:
Is it getting more attention these days because there are more cases?

EHRESMANN:
I think there's a recognition that, historically, the information that was available to public health about some of these fungal diseases was really limited to case reports and what was found through outbreak investigations. And there's a recognition that may not be providing us with the complete, accurate picture of what's going on with these diseases.

So, CDC is working with 10 states to look more in depth at histoplasmosis, to do more in depth surveillance, and the hope is that that will help to provide additional data so that we have a more robust picture of what this disease is actually means for us.

So, it is serious, and I think there's a recognition that we need to look at it more completely. And so, we're participating in Minnesota, along with 10 other states in an enhanced surveillance program.

JOHNSON:
Is this easy to diagnose when a patient is in a physician's office?

EHRESMANN:
I think it's fair to say that the diagnosis of histoplasmosis is often delayed. We know that a lot of the cases that are reported to us—upwards of 64%—have been to their provider multiple times. And so, I think it's fair to say that fungal infection is not always top of mind for a clinician when they're evaluating a patient with pulmonary symptoms.

And that's why it's important that public health continues to get information about this disease so we can make sure that providers are aware that when you have a patient that comes in who has a certain exposure history or certain classic symptoms that you consider a fungal infection as part of the differential. And so, the more that we're aware of what's really happening with diseases, the better information we can provide the clinician.

But the bottom line is that diagnosis is often delayed, and we would like to see patients getting treated more quickly because that can make a difference in the course of their illness.

JOHNSON:
Given where this fungus likes to hang out—on farms and at construction sites or in the dirt in general—do you target your education toward any particular groups of employees or working groups to make sure that they understand what the risks might be as they go about their daily jobs?

EHRESMANN:
We're trying to do a better job of getting information out through social media and those types of things, both based on, you know, where we're seeing cases happening in the state, based on geography, as well as on, as you said, risk factors. So, you know, if you're spending a lot of time working in soil, that type of thing.

I think it's fair to say that our work with some of these fungal diseases is really beginning. And so, we're looking at establishing strong surveillance and epidemiologic data. And then, as those programs are strengthened, then outreach and public education follow.

JOHNSON:
And the public education piece is really the role of public health.

EHRESMANN:
It's all part of our role, but it sort of speaks to program development: and so, initially you starting to look at case reports, where are we seeing with outbreaks; you establish then some basic sort of enhanced surveillance; you build up the epi-data that you have; and then, as you've strengthened that information, then you build on that and look at, "Okay, how are we going to use these data to prevent disease in the public?"

JOHNSON:
Links to information about fungal diseases can be found in the show notes for this episode.

Thanks for listening to Public Health Review. If you liked the show, please share it with your colleagues.

And if you have comments or questions, we'd like to hear from you. Email us at pr@astho.org—that's PR at ASTHO dot org.

This show is a production of the Association of State and Territorial Health Officials.

For Public Health Review, I'm Robert Johnson. Be well.