Tb

Are you being treated for active TB or latent TB? If you received a positive skin test (above 10mm or 15mm depending on your risk group) and a negative CXR, you should be treated with 9 months of INH. This is the appropriate therapy for latent TB.

No. I just had a general question. Our infection control dept informed us that even w/ BCG vaccine pts should be treated for 9mos if they have a positive ppd. I was never aware of this. I was under the impression that if a pt was vaccinated, a positive ppd meant immunity not exposure. Just a bit confused.

Our infection control dept informed us that even w/ BCG vaccine pts should be treated for 9mos if they have a positive ppd. I was never aware of this. I was under the impression that if a pt was vaccinated, a positive ppd meant immunity not exposure.

BCG provides protection against disseminated TB in children. It provides no protection against pulmonary TB or TB in adults. PPD reaction from BCG usually wanes, so that a positive PPD in an adult who had received BCG as a child is a relatively specific indicator of TB infection.

As for the specifics of treatment of latent TB, I recommend the Core Curriculum on Tuberculosis from the CDC. http://www.cdc.gov/tb/pubs/corecurr/

Because antitubercular drugs are toxic, treatment of latent TB is not automatically recommended for everyone with LTBI - but I've forgetten the specifics - it's in the Core Curriculum.

I had a pos ppd at 10 mm and a negative cxr. I was treated c/ 7mo of INH. The following year, I again had a ppd only this time, it had NO reaction! I wish I had demanded a repeat test before starting the treatment. It is toxic! Further, my PCP (at the time) did not explain the full implications of INH.

I had a pos ppd at 10 mm and a negative cxr. I was treated c/ 7mo of INH. The following year, I again had a ppd only this time, it had NO reaction! I wish I had demanded a repeat test before starting the treatment. It is toxic! Further, my PCP (at the time) did not explain the full implications of INH.

Hmmm, was your "positive" PPD indurated, or just red? Redness is NOT a positive PPD - it has to be indurated to be positive.

Mine often turn red, but that's just irritation from the injection, not an immune reaction to the TB antigen.

ok so now I'm more confused.... if you were vaccinated and test positive )5mm or more induraton) w/ the antigen how do u really know that u have a latent infection? And also, now you go months being treated w/ INH or Rifampin (which is the second line treatment of choice) how r u safe from re-exposure? After tx shouldn't ur ppd still be positive if you had the antigen? my head is spinning:uhoh3:

And also, now you go months being treated w/ INH or Rifampin (which is the second line treatment of choice) how r u safe from re-exposure? After tx shouldn't ur ppd still be positive if you had the antigen? my head is spinning:uhoh3:

I would like to know the answer to those two questions also! I believe there is a lot of misinformation about TB.

ok so now I'm more confused.... if you were vaccinated and test positive )5mm or more induraton) w/ the antigen how do u really know that u have a latent infection? And also, now you go months being treated w/ INH or Rifampin (which is the second line treatment of choice) how r u safe from re-exposure? After tx shouldn't ur ppd still be positive if you had the antigen? my head is spinning

After a person receives BCG she/he will have a positive PPD for a period of time (I can't tell you specifically how long, but it's usually a moot point anyway - BCG is given to children). The reaction to the BCG wanes by the time the person reaches adulthood, so that unless a person has been exposed to M. tuberculosis she/he will test negative. (BCG is not the only vaccine for which the immunity wanes over time - pertussis and smallpox are two that come to mind).

Therefore, if a person who has received BCG as a child has a positive PPD as an adult, it is a relatively specific indicator that that person has LTBI.

Again, the immunity conferred from BCG is only against disseminated TB in children - and the amount of immunity conferred is controversial.

It sounds to me that what HappyDay is saying is that he was treated for a what was presumed to be a positive PPD, but later had a negative PPD that indicated that he had not had LTBI - but HappyDay will need to clarify that. A positive PPD is indurated. If the PPD becomed reddened, but is not indurated, it is still a negative result - it just looks positive.

BTW, I really don't think it's appropriate for a PCP to treat LTBI - the public health department should have been notified and should have guided treatment.

"A diagnosis of M. tuberculosis infection and the use of treatment for infection should be considered for any BCG-vaccinated person who has a tuberculin skin-test reaction of >= 10 mm of induration"

http://www.cdc.gov/tb/pubs/corecurr/Chapter9/Chapter_9_Interpretation.htm

"The TST [tuberculin skin test] should not be performed on a person who has a documented history of either a positive TST result or treatment for TB disease."

"The BCG (bacillus CalmetteGuerin) vaccine is currently used in many parts of the world where TB is common to protect infants and young children from serious, lifethreatening disease, specifically miliary TB and TB meningitis. The World Health Organization (WHO) recommends BCG vaccination once in infancy in TB endemic countries. The question of the effect of BCG vaccine on TST results often causes confusion. TST reactivity caused by BCG vaccine generally wanes with the passage of time, but periodic skin testing may prolong (boost) reactivity in vaccinated persons."

"A history of BCG vaccine is not a contraindication for tuberculin skin testing or treatment for LTBI in persons with positive TST results. TST reactions should be interpreted regardless of BCG vaccination history"

POSTTREATMENT FOLLOW UP

• Patient should receive documentation of TST or QFT [QuantiFERON TB test] results and treatment completion that includes name, dates, chest radiograph, and dosage and duration of medication. The patient should be instructed that he or she should present this document any time future testing is required.
  
• Patient should be reeducated about the signs and symptoms of TB disease and told to contact his or her medical provider if he or she develops any of these signs or symptoms.
  
• Regardless of whether the patient completes treatment for LTBI, serial or repeat chest radiographs are not indicated unless the patient develops signs or symptoms suggestive of TB disease.

http://www.cdc.gov/tb/pubs/ltbi/pdf/targetedltbi05.pdf

I hope this helps. IMO, the CDC is the best source of information on TB availalbe on the Internet.