
TB infection threatens the immune compromised
Transcript
[00:00:01] Host Amber Smith: Upstate Medical University in Syracuse, New York invites you to be "The Informed Patient" with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith. When you consider infectious diseases worldwide, tuberculosis remains a leading cause of death. Today I am talking with an infectious disease doctor who specializes in tuberculosis, Dr. Elizabeth Harausz. She's an assistant professor of medicine at Upstate. Welcome back to "The Informed Patient," Dr. Harausz.
[00:00:33] Elizabeth Harausz, MD: Thank you. Thanks for having me.
[00:00:36] Host Amber Smith: So what is tuberculosis?
[00:00:39] Elizabeth Harausz, MD: Tuberculosis is a mycobacterial, which means it's a type of bacteria infection. It's an infection that mostly affects the lungs, meaning that it causes pneumonia. It's an unusual infection in that in most people who are infected with tuberculosis, they will never become sick, and therefore they'll never be contagious, meaning able to spread the infection to other people. And this is called latent TB.
With latent TB, the person's immune system is controlling the infection. And about 90% of people with normal immune systems who are infected with TB will never develop any symptoms and never become sick and spend their whole lives with latent TB and absolutely no symptoms.
However, in about 10% of people with normal immune systems, sometime during the person's life, often years after the initial infection, the TB germ will escape the immune system's control, and the person will become sick with bad pneumonia. This is called active tuberculosis, or active TB.
However, these symptoms have a slow onset over weeks to months, and these symptoms steadily progress. The symptoms don't come and go like cold or allergies or something like that. And untreated, active tuberculosis only has about a 20% survival rate. And people with normal immune systems, and people with significant immune suppression, will not survive without treatment.
[00:02:05] Host Amber Smith: But you said latent TB, so a person could be infected with this and have no knowledge that they're a carrier?
[00:02:13] Elizabeth Harausz, MD: Correct. Yep. In latent TB, people have absolutely no symptoms, but it could in the future,come back and cause, and kind of rise up and cause symptoms.
It's not entirely clear if there's really, truly kind of living bacteria in all those people. In some people maybe the immune system killed it and it would never come back. But there's no way to know what people's immune systems have completely eradicated or which people it may come back. But being infected by tuberculosis and not having symptoms, we just call all of that latent TB.
[00:02:48] Host Amber Smith: And if you have latent TB, you're not contagious with it? You can't spread it to other people?
[00:02:54] Elizabeth Harausz, MD: Correct. Not with latent TB. People have to be sick with symptoms, to be able to be contagious.
[00:03:01] Host Amber Smith: Do we have any idea what percent of Americans might have latent TB?
[00:03:06] Elizabeth Harausz, MD: It is hard to say, because lots of times people don't seek attention for it. because they don't have any symptoms, they wouldn't necessarily know. But it's fairly low, maybe about 3% of the population has in the United States -- to make that very clear -- in the United States has latent TB, meaning they've potentially been infected with tuberculosis sometime in their lifetime.
[00:03:32] Host Amber Smith: So if I understand correctly, in America, the way a person might find out they have TB is when they develop a pneumonia and they end up in the hospital or a doctor's office, and testing is done, and that's how you discover, oh, you've got TB?
[00:03:49] Elizabeth Harausz, MD: Yeah. Although in this country, having active tuberculosis is fairly uncommon.
The rate of active tuberculosis, of people becoming sick in this country is only about three people per every a hundred thousand people in this country. So, quite rare. So people generally presenting with active tuberculosis would come in quite sick and then be probably diagnosed in the hospital.
Latent tuberculosis, much more common, but probably more often diagnosed if people have potentially known risk factors and have a screening test done, or have a known contact with somebody with active tuberculosis.
[00:04:26] Host Amber Smith: Well, where in the world is TB more of a problem?
[00:04:31] Elizabeth Harausz, MD: Active tuberculosis, the countries with the highest burden with people becoming sick with tuberculosis are generally in Africa and Southern Asia. However, eastern Europe, although it may not have the absolute numbers of those countries, has quite high rates of drug resistant tuberculosis, which makes treatment, more difficult.
[00:04:52] Host Amber Smith: How is it treated?
[00:04:54] Elizabeth Harausz, MD: Treatment is long, a bit longer than you would think, but it's 100% curable. So the standard treatment for tuberculosis, active tuberculosis, is four antibiotics for two months, and then take two antibiotics for six months. There's actually a new regimen, which is four antibiotics for two months, and then three antibiotics for two months.
So the problem is this is a very slow growing organism, so it doesn't make you sick quickly. People generally when they get sick, they'll have symptoms for weeks and potentially months. But it also therefore kind of takes a long time to kill. But as I mentioned, the treatments are very effective, and a person can be expected to heal completely if they take all of their medication.
And for the most part, these antibiotics are specific for TB, and they wouldn't be antibiotics that you would generally be getting for other infections.
[00:05:48] Host Amber Smith: Now, is active TB very contagious? Would the person need to be isolated?
[00:05:54] Elizabeth Harausz, MD: Yes. So if somebody does have active tuberculosis, they are put on isolation until we start treatment on them. And then once they are treated, probably much quicker than two weeks, but kind of the rule is after about two weeks, we retest the sputum cultures to make sure the organism's no longer there. And if it's not in the sputum, the person still has the infection, but it's not contagious.
And as long as they're on their medicines, then they don't have to be isolated anymore.But it's not that easy. I mean, it is contagious, but it's actually not that easy to get tuberculosis. It is an airborne infection, meaning that it spreads when a person who is sick with active symptoms, therefore having active TB, coughs and then the germ spreads into the air and another person breathes it in. But it's not nearly contagious as all the respiratory viruses and the colds and such.
To be at risk for becoming infected with tuberculosis, you need to be a close contact of someone who's actively sick. So not somebody with latent TB, but somebody that's actively sick. And this is generally the rule is kind of that being in an enclosed space with a person actively sick for at least four hours per week. And as you may remember, this just means that you may develop latent TB, not that you will develop active TB immediately after being exposed.
[00:07:14] Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith. I'm talking with infectious disease specialist Dr. Elizabeth Harausz, who has expertise in tuberculosis.
TB was the leading cause of death in the United States in the early 1900s. How was it diagnosed and treated back then?
[00:07:35] Elizabeth Harausz, MD: Back then, it was treated based on clinical symptoms, and then chest x-rays, which they had around, kind of developed around the turn of the century.
And alsoin like the late 1800s, they actually discovered which germ was causing tuberculosis, and they found they could see it under a microscope when looking at sputums. So that was kind of the early diagnosis. There was no antibiotics to treat it, actually, until the 1940s, and they discovered like one or two. And then a few more antibiotics were discovered through the 1950s, 1960s, 1970s.
But before antibiotics, many people, hopefully, if you were lucky, you were able to go to a TB sanatorium for treatment, which were kind of hospitals out in the country, where the treatment -- they didn't really have antibiotics -- was basically clean air, rest and good nutrition.
[00:08:26] Host Amber Smith: Is that how TB was eradicated with a combination of the various antibiotics and the sanitariums?
[00:08:34] Elizabeth Harausz, MD: Well, so it's not eradicated. It's just in low numbers in this country. So it's still one of the I think actually the No. 1 infectious disease killer in the world. COVID took that title for about a year, but TB is back at the top, unfortunately. But yeah, I mean, the sanatoriums did help. I mean the air back then, it was really in the cities was filthy. So being in clean air and good nutrition and rest, you know, helped improve people's immune system and helped to whatever degree it could to fight the tuberculosis and perhaps be cured. But what really helped was public health and social welfare measures Had most of the initial benefits. So programs to combat malnutrition and improve living and working conditions. So the numbers there of active TB started to fall with that.
And then followed by treatment for active TB and treatment of latent TB, with a health care system that had the money to do so. So it really was the departments of health that were the heroes in decreasing the rates of TB. And by finding people who had active TB and by treating people with the active TB and finding those who had been exposed and treating them for latent TB and therefore preventing further progression of illness.
[00:09:46] Host Amber Smith: Well, getting back to TB in America today, I just wanted to talk about the prognosis for someone who is diagnosed with latent TB who has a suppressed immune system. Does that put them at higher risk?
[00:10:00] Elizabeth Harausz, MD: Yes. So somebody with a normal immune system has about a 10% chance in their lifetime of progressing to active tuberculosis. But somebody with a suppressed immune system has a much higher rate. And it really depends on how suppressed their immune system is, but if your immune system is suppressed, you can't control the tuberculosis as well.
What we see, really, in this country is people who are going on immune suppressive medications, like certain rheumatological medicines. They'll be screened for tuberculosis before they start those. Even though the rates of tuberculosis in this country are quite low, they'll be screened for latent tuberculosis and treated if necessary just because it's something that's easy to treat and would be bad if it wasn't caught and treated.
[00:10:46] Host Amber Smith: Now if someone is discovered to have TB and it's treated, does that offer them any immunity from developing TB again?
[00:10:54] Elizabeth Harausz, MD: Yes, to some degree it does. Although, there are people who, if you have very high rates of exposure to tuberculosis, it can reoccur. But those conditions generally don't occur in this country. I'm talking about, like, miners in South Africa and that sort of thing with very, very high rates of tuberculosis and very poor lung conditions.
So it is possible to get it, to have a reinfection. I mean, if you're treated, it's not going to come back, treated correctly and take all your medicines, but you could be reinfected. But again, being exposed to tuberculosis is fairly unlikely. So being exposed a second time and with whatever kind of increased immunity that you have, so it's pretty unlikely to ever have it a second time.
[00:11:41] Host Amber Smith: Well, here in the US and in developing nations, what can people do to reduce their risk of getting TB?
[00:11:48] Elizabeth Harausz, MD: So really the best defense against becoming ill with TB, is knowing when you have been exposed to someone with active tuberculosis and getting the appropriate preventative treatment. And the people who do this -- meaning people who keep track of active cases of TB and treat people who have been exposed -- is our Department of Health.
And that's why it's so important for a whole host of reasons to make sure our departments of health are well funded and well functioning.
[00:12:16] Host Amber Smith: Good to know. Well, thank you so much for making time for this interview, Dr. Harausz.
[00:12:20] Elizabeth Harausz, MD: Oh, you're entirely welcome.
[00:12:22] Host Amber Smith: My guest has been Dr. Elizabeth Harausz. She's an assistant professor of medicine at Upstate specializing in infectious disease. "The Informed Patient" is a podcast covering health, science and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe with sound engineering by Bill Broeckel and graphic design by Dan Cameron. Find our archive of previous episodes at upstate.edu/informed. If you enjoyed this episode, please invite a friend to listen. You can also rate and review "The Informed Patient" podcast on Spotify, Apple podcasts, YouTube, or wherever you tune in. This is your host, Amber Smith, thanking you for listening.