# Chest Xray and Tuberculosis **URL:** \ **Category:** Factual Questions\ **Created:** [October 14, 2012, 12:25am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659 "2012-10-14T00:25:09Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [October 14, 2012, 12:25am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/1 "2012-10-14T00:25:09Z")
Several times when I was a kid, my mother warned me never to get a chest xray. The reason? Back in the early 1930s, long before I was born, my paternal grandfather died from tuberculosis. My father was with him during the course of his disease. Because of this, my father was identified as a carrier, and he could have passed it down to us kids. Supposedly, after all these years, a chest xray could activate it. Ignoring my mother’s warnings, I’ve had several chest xrays over the years, especially in the last couple of months, related to my heart surgery. So far, nothing has happened. So was this a realistic fear, based on medicine of the early 1930s, or are my lungs a ticking time bomb? ---
**Author:** ![Shmendrik](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@Shmendrik](https://boards.straightdope.com/u/Shmendrik)\ **Post date:** [October 14, 2012, 12:31am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/2 "2012-10-14T00:31:26Z")
> [@panache45](#): > > Several times when I was a kid, my mother warned me never to get a chest xray. The reason? Back in the early 1930s, long before I was born, my paternal grandfather died from tuberculosis. My father was with him during the course of his disease. Because of this, my father was identified as a carrier, and he could have passed it down to us kids. Supposedly, after all these years, a chest xray could activate it. > > Ignoring my mother’s warnings, I’ve had several chest xrays over the years, especially in the last couple of months, related to my heart surgery. So far, nothing has happened. > > So was this a realistic fear, based on medicine of the early 1930s, or are my lungs a ticking time bomb? It’s certainly not a realistic fear based on the medicine of the early 2010’s. A chest X-ray may show evidence of active or old TB infection, but it will not activate TB. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [October 14, 2012, 12:38am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/3 "2012-10-14T00:38:54Z")
It doesn’t make any sense to me. You do know that we are all exposed to radiation on a daily basis, right. Airline workers are exposed to a higher level due to the altitude in which they work, and obviously workers in the nuclear industry are, or can be, exposed to higher levels too. Radiation is all around us, but it’s cumulative exposure that’s the issue. There are workplace guidelines on how much cumulative exposure workers like pilots and flight attendants and nuclear workers can be exposed to. I wear a dosimeter at work every day, and I wear a Personal Alarming Dosimeter (PAD) when I’m in active areas. The dosimeter soaks up the cumulative exposure, and I get a yearly report on my levels, as does everyone else in the company. Radiation isn’t that scary, as long as your cumulative exposure is below well-established safe levels. I’ve never, ever heard any link to tuberculosis and wonder what the connection between a bacterial infection and excess gamma radiation might be. ---
**Author:** ![jabiru](https://avatars.discourse-cdn.com/v4/letter/j/bbce88/32.png) [@jabiru](https://boards.straightdope.com/u/jabiru)\ **Post date:** [October 14, 2012, 2:39am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/4 "2012-10-14T02:39:51Z")
My family history parallels that of the OP. My maternal grandfather died of TB in 1934. My mother (his youngest and favourite child) was four when he died and, as much as my grandmother tried to keep Mum away from her father for Mum’s own safety, she spent most of her waking hours with him right up until his death. Neither Mum nor I have ever been told of the chance TB could activate in either of us. I’ve nursed many patients with TB and have had lots of chest x-rays without event. ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [October 14, 2012, 2:45am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/5 "2012-10-14T02:45:43Z")
> [@Shmendrik](#): > > It’s certainly not a realistic fear based on the medicine of the early 2010’s. A chest X-ray may show evidence of active or old TB infection, but it will not activate TB. Yeah, I’m suspecting his mom misheard/misunderstood how chest x-rays can show evidence of TB. I work in a hospital and if you test positive at your annual TB test, you need to have a chest x-ray done to prove you don’t have it. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [October 14, 2012, 5:04am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/6 "2012-10-14T05:04:51Z")
This is pretty much what I’ve suspected. My father was a teenager at the time, and probably totally misunderstood what he was told. ---
**Author:** ![allotrope](https://avatars.discourse-cdn.com/v4/letter/a/edb3f5/32.png) [@allotrope](https://boards.straightdope.com/u/allotrope)\ **Post date:** [October 14, 2012, 5:11am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/7 "2012-10-14T05:11:08Z")
I had a chest x-rays every 6 months for most of the 60’s and 70’s as the result of false positive TB tine tests. I’m not especially worried about it even though the milliseverts produced by those old x-ray machines were probably quite a bit higher than what you would be exposed to now. ---
**Author:** ![BMax](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bmax/32/4267_2.png) [@BMax](https://boards.straightdope.com/u/BMax)\ **Post date:** [October 14, 2012, 5:12am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/8 "2012-10-14T05:12:39Z")
> [@Ferret\_Herder](#): > > Yeah, I’m suspecting his mom misheard/misunderstood how chest x-rays can show evidence of TB. I work in a hospital and if you test positive at your annual TB test, you need to have a chest x-ray done to prove you don’t have it. This brings up a question: I’ve been given the TB skin test, and developed bumps from it, which is a positive, but my chest X-ray was clean. Could this be from an earlier TB vaccination? Do they, or did they vaccinate for TB in the USA? I was inoculated with just about everything when I joined the army in the 80’s. ---
**Author:** ![Danja](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@Danja](https://boards.straightdope.com/u/Danja)\ **Post date:** [October 14, 2012, 5:25am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/9 "2012-10-14T05:25:03Z")
> [@BMax](#): > > This brings up a question: I’ve been given the TB skin test, and developed bumps from it, which is a positive, but my chest X-ray was clean. Could this be from an earlier TB vaccination? Do they, or did they vaccinate for TB in the USA? I was inoculated with just about everything when I joined the army in the 80’s. How big of bumps are we talking? I was born in a TB vaccinating country and when I went for my first TB skin test about a year ago my bumps were larger than the images in the doctor’s reference sheet. She thought I was supposed to be dead until I remembered my immunization and explained the situation. If you’ve got active immunity I’d expect you to have a pretty strong reaction (but of course IANAD). ---
**Author:** ![AK84](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@AK84](https://boards.straightdope.com/u/AK84)\ **Post date:** [October 14, 2012, 8:55am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/10 "2012-10-14T08:55:56Z")
To the OP, it’s not unknown for hospital equipment to be contaminated with some bug. Not sure if TB can be passed on that way. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [October 14, 2012, 9:44am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/11 "2012-10-14T09:44:29Z")
> [@BMax](#): > > This brings up a question: I’ve been given the TB skin test, and developed bumps from it, which is a positive, but my chest X-ray was clean. Could this be from an earlier TB vaccination? Do they, or did they vaccinate for TB in the USA? I was inoculated with just about everything when I joined the army in the 80’s. The US does not routinely vaccinate against TB. If you ever are vaccinated against TB, though, you will forever afterward show a positive skin test. It is also possible you were exposed to TB at some point and developed a robust collection of antibodies without ever actually coming down with the disease, in which case, again, you will show a positive skin test. This is why a positive skin test isn’t a diagnosis, and why you need the chest x-ray to be certain. ---
**Author:** ![even\_sven](https://avatars.discourse-cdn.com/v4/letter/e/dfb087/32.png) [@even\_sven](https://boards.straightdope.com/u/even_sven)\ **Post date:** [October 14, 2012, 1:40pm UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/12 "2012-10-14T13:40:48Z")
If you have been exposed to TB in any way (carrier, active illness, exposure, vaccine) you will have a positive result on the skin test. The skin test doesn’t tell you that you have TB, just that you have at some point made antibodies for it. People who test positive on a skin test will always need X-rays to determine if they have TB or not. One of the reasons why the US does not administer the TB vaccine is that the risk from regular chest X-rays is not worth the cases of TB that the vaccine (which isn’t all that great) would prevent. It sounds to me like the OP’s relative conflated getting diagnosed via X-ray with getting active TB, and made a mistaken connection in their mind. ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [October 15, 2012, 12:47am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/13 "2012-10-15T00:47:48Z")
> [@even\_sven](#): > > If you have been exposed to TB in any way (carrier, active illness, exposure, vaccine) you will have a positive result on the skin test. Not true. What a positive skin test strongly suggests is that the person has been infected with TB bacilli. Mere exposure is not sufficient, and while BCG vaccination for TB [may](http://www.cdc.gov/tb/topic/testing/default.htm) cause a positive test in some instances, often it does not. And people can initially have a positive skin test (PPD) while later testing negative, suggesting their body has cleared the infection. Also, a chest x-ray is not the only means of diagnosing active TB - there can be false positives (for instance, from remote fungal or other granulomatous process) and other testing including TB blood or sputum tests may be used. I know of no evidence that getting a chest x-ray activates TB. A common factor in activation of quiescent disease is that the immune system weakens/fails in some way, allowing infection to spread. ---
**Author:** ![Fish\_Cheer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fish_cheer/32/17179_2.png) [@Fish\_Cheer](https://boards.straightdope.com/u/Fish_Cheer)\ **Post date:** [October 15, 2012, 12:58am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/14 "2012-10-15T00:58:54Z")
> [@Broomstick](#): > > It is also possible you were exposed to TB at some point and developed a robust collection of antibodies without ever actually coming down with the disease, in which case, again, you will show a positive skin test. > [@even\_sven](#): > > If you have been exposed to TB in any way (carrier, active illness, exposure, vaccine) you will have a positive result on the skin test. The skin test doesn’t tell you that you have TB, just that you have at some point made antibodies for it. The PPD test does not detect antibodies. > [@](#): > > Reaction in the skin to tuberculin PPD begins when specialized immune cells, called [T cells](http://www.medicinenet.com/script/main/art.asp?articlekey=11300), which have been sensitized by prior infection, are recruited by the immune system to the skin site where they release chemical messengers called lymphokines. These lymphokines induce [induration](http://www.medicinenet.com/script/main/art.asp?articlekey=15911) (a hard, raised area with clearly defined margins at and around the injection site) through local vasodilation (expansion of the diameter of blood vessels) leading to fluid deposition known as [edema](http://www.medicinenet.com/script/main/art.asp?articlekey=12699), fibrin deposition, and recruitment of other types of inflammatory cells to the area. > **[Tuberculosis PPD Skin Test: Ranges, Results, Readings and Risks](https://www.medicinenet.com/tuberculosis_skin_test_ppd_skin_test/article.htm)** > > The tuberculosis skin test checks if a person has developed an immune response to the bacterium causing TB. Learn more about the test, its readings, and its results. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [October 15, 2012, 2:26am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/15 "2012-10-15T02:26:06Z")
> [@panache45](#): > > Several times when I was a kid, my mother warned me never to get a chest xray. The reason? Back in the early 1930s, long before I was born, my paternal grandfather died from tuberculosis. My father was with him during the course of his disease. Because of this, my father was identified as a carrier, and he could have passed it down to us kids. Supposedly, after all these years, a chest xray could activate it. Apparently your mother believed that TB is genetically transmitted. If your dad had the bug, he could have passed it to you kids, to her, to the grocer… and if you have it, you’ll be positive for the Tuberculine test, but that doesn’t mean you _will_ have TB. 98% of people in Spain are positive for Tuberculine (the other 2% haven’t been tested), yet the incidence of actual tuberculosis is in the one-in-millions range. A chest X-ray is what’s used to detect Tuberculosis (as opposed to the presence of its bacterium), but it doesn’t “activate” it any more than an arm X-ray causes broken bones. ---
**Author:** ![KarlGrenze](https://avatars.discourse-cdn.com/v4/letter/k/dbc845/32.png) [@KarlGrenze](https://boards.straightdope.com/u/KarlGrenze)\ **Post date:** [October 15, 2012, 11:09am UTC](https://boards.straightdope.com/t/chest-xray-and-tuberculosis/637659/16 "2012-10-15T11:09:27Z")
> [@BMax](#): > > Do they, or did they vaccinate for TB in the USA? I was inoculated with just about everything when I joined the army in the 80’s. Info about the BCG vaccine: It is not a really good vaccine for protecting against the classical TB form (lung infection). The TB bacterium can cause disease in a few different ways. In kids, for some reason or other, it does not cause the typical lung problems, but instead causes a serious meningitis (infection around the brain). BCG may not be a good vaccine for the classical form of TB, but it was found to be an excellent vaccine against the childhood form of the disease. So it is included as part of the _childhood_ vaccinations in most other countries. Although the army may vaccinate against everything, it’d be a bit odd for them to give a childhood vaccine, especially when it does not offer awesome protection against the adult form.