Tuberculosis and Mantoux Test

12:40 PM
Tuberculosis is one of the most common and lethal infectious disease around the globe. It is thought that one third of the world's population is infected by the Mycobacterium Tuberculosis---its causative agent. According to World Health Organization, most death cases occur in developing countries due to compromised immunity. The risk of contracting this disease is highest for those who have HIV because people with that disease have compromised immune system. {Sidenote: Lately, HIV cases here in the Philippines had soared its way up to 587%, which is kind of, scary.}

Tuberculosis has a triad of symptoms namely: weight loss, low grade fever (at night) and chronic cough. When do we say that a cough is already a chronic one you ask? A cough lasting for more than eight weeks is considered chronic and I suggest that, in that case, you should consult a doctor immediately! If you experience the above triad of symptoms, don't panic right away. It doesn't always mean that you have tuberculosis.

There is a diagnostic test that we can actually do to determine if you've been exposed to the M. Tuberculosis. It's called Mantoux test/ tuberculin test/ PPD test. It is done by injecting (yes it hurts!) 0.1ml of the Purified Protein Derivative into the layers of your skin, preferably on the forearm. Result is read 48-72 hours after the injection.

This is my forearm 6 hours after the injection! >_<
There would be a reaction if you've been exposed to the bacteria. It's called an induration---a raised, palpable, hardened area. Take note that the area of redness is not measured.

When I was still working in the Rural Health Unit, my superior taught me how to measure the induration. It can be done by running a ballpen near the site of injection. You will feel a "bump" if there is an induration. (The pen magically stops!) You have to do it on four sides of the injection site. And when you're done, draw a square for easier measurement. I don't know if it affects the reading, what do you think? See picture below:

They told me it's positive!
You have to measure the square. If you get a reading of more than 10mm, it's positive. However, for a more detailed explanation, I copied the ff from wikipedia:

  • 5 mm or more is positive in
    • An HIV-positive person
    • Persons with recent contacts with a TB patient
    • Persons with nodular or fibrotic changes on chest X-ray consistent with old healed TB
    • Patients with organ transplants, and other immunosuppressed patients
  • 10 mm or more is positive in
    • Recent arrivals (less than five years) from high-prevalence countries
    • Injection drug users
    • Residents and employees of high-risk congregate settings (e.g., prisons, nursing homes, hospitals, homeless shelters, etc.)
    • Mycobacteriology lab personnel
    • Persons with clinical conditions that place them at high risk 
    • Children less than four years of age, or children and adolescents exposed to adults in high-risk categories
  • 15 mm or more is positive in
    • Persons with no known risk factors for TB

Having a positive result doesn't mean you have Tuberculosis. It only means that you've been exposed to the bacteria. You can have your chest x-ray taken or go do the confirmatory test for Tuberculosis---which is called Sputum AFB(Acid Fast Bacilli).

People in the medical field (ahem!) are more likely to have a positive PPD reading as they are frequently exposed to patients who are carrying that bacteria. It is best to always wear a mask and take good care of your immune system to avoid getting the TB. 

SideNote: I still believe that my PPD reading was false-positive because we fooled around my injection site when it got red. See how I developed a bruise on the site? lol. My chest x-ray was clear! :)

Tuberculosis can be cured, if diagnosed early. The Philippine government has this program called TB DOTS (Direct Observed Treatment Shortcourse). They give free medicines and monitor the patient's progress through the help of RHUs. It is just sad that people are scared to be tested because of the stigma that surrounds this disease.

Piece of unsolicited advice: "Prevention is STILL better than cure. So, if you suspect somebody, or you know somebody who has TB, persuade him/her to get tested and of course, treated. We do not want to spread the disease, do we?"

Keep safe everyone!

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  1. My father did this kind of a test. Yes, he really had TB but then after 6 months of taking medicines he had his sputum test. HE IS NOW NEGATIVE from TB.

  2. Now I know that the injection test for tuberculosis is called Mantoux Test. Today, people with tuberculosis has nothing to worry about because it can be completely cured now with medicines unlike before wherein people see it as a contagious plague.

  3. If one person used this method and the result is positive, he/she might go crazy and then after having another diagnose with the physician, the result can turn out to be the opposite. So I'm interested to know...What is the accuracy rate of this PPD reading?

  4. I like this post! Very informative.. yes, I definitely agree that prevention is better than cure! So let's all go back to basics.. eat more fruits and veggies!!!

  5. There's a stigma indeed. I hope people will smarten up and allow themselves to be tested instead of just living with it and "hope it goes away."

  6. I remember my grandma having this test. She DID have TB and she went on to have an operation. She's fine now :)

  7. These are helpful tips for easy detection of HIV and also promotes awareness on the disease.

  8. wow this is very helpful post dear! i would love to read more of this! for my family's safety also! xx

  9. my uncle had TB but is well now, thanks to medicines. this information is worth taking note. thanks

  10. I can't remember if this test was done to me. Basta ang alam ko, I have most of a TB symptoms. But that ages ago. Drugs and alcohol was the culprit.

  11. Now I am learning. Great to know some more info about it. I am seeing a lot of hospitals displaying some sort of banner with the letters DOTS in them. Now I know what does it mean. Thanks!

  12. I didn't had to go under this test when I was diagnosed to have PTB. I immediately coughed out blood that time. Good thing TB nowadays can be cured with medicines.

  13. It may sound technical to me, but I do believe this post is such a great help especially in promoting awareness on the disease.

    Rochelle Caparas

  14. I love how you've made me read a topic that I've thought would be boring. It was informative. And I really think it's painful because they'll inject something in which was more painful than just giving blood samples.