Thursday, March 28, 2013

Tuberculosis Made Easy

Tuberculosis (TB) is a contageous infection that is caused by a bacterium called Mycobacterium tuberculosis. One third of the world population has been infected with TB and it caused over 1.5 million deaths in 2010.  We don't hear as much about TB in the developed world but new infections in third world countries occur at a rate of about 1 per second.    Risk factors for TB are:
  • A weakened immune system such as diabetes or HIV
  • Working in health care or refugee camps
  • Traveling to countries where TB is endemic
  • Living in overcrowded situations or extreme poverty
 The disease usually affects the lungs and is spread when people cough or sneeze and spray moisture droplets.  In the old days, TB was called "consumption" and at the turn of the century it was treated by isolating patients in sanitariums for months to years and hoping they recovered. In the 19th Century, TB killed more people in New England than any other disease.


Active TB is when a person has symptoms (fever, cough, night sweats, fatigue, wasting) and has a positive ppd skin test.  These people can spread the bacteria.

Latent TB is when a person with no symptoms has a positive ppd skin test and the bacteria is in a dormant or inactive state.  These people are not contagious.  A chest XRay can distinguish between active and latent TB.

We treat patients who have active TB with antibiotics and treatment usually lasts for 6 months to get rid of the infection.  Persons with latent TB are also treated as a preventive for the infection flaring up again.  Multidrug-resistant TB is a form of active TB caused by bacteria that do not respond to the medications most commonly used to treat TB.

Health care workers, child care workers, home-care professionals and immigrants should all have regular ppd tests to make sure they have not been exposed to TB.  Once a ppd test is positive, it will always remain positive, even if the infection has been treated and resolved.

6 comments:

Anonymous said...

MAC, not well known, has been called a second cousin to TB. I'd like to know if there is current research going about Microbacterium Avium Complex. It is increasing in numbers, not affecting men as well as older women and there is a high recurrence rate after the present very high dosage antibiotic treatment. Love your blog

Raymond Bouchayer said...

When I was leaving in France I had to go get a BCG , they srached my shoulder with some kind of med. it is supposed to prevent TB and many other desease. Now I show a positive TB test
Is it done here in the US ?

Toni Brayer, MD said...

Anon 5:41AM: MAC(mycobacterium Avium Complex) is indeed a different bacteria that deserves it's own blog post. It is increasing in number, especially in women for reasons that are unknown. These organisms are common in the environment and multidrug treatment is needed for a long period of time. According to CenterWatch, there are no ongoing patient trials in MAC.

Toni Brayer, MD said...

Raymond Bouchayer: You are correct that in developing countries (was that France?) BCG is used as a vaccine for TB. It is a weak vaccine and that is why it is not used everywhere. Once a person is vaccinated with BCG, they will always have a positive ppd skin test so there is no reason to ever get the ppd test again. If TB is suspected, a Chest Xray and tissue sample is needed for diagnosis.

Susan Yoga said...

Now TB is curable and if the infected person get a proper medication and food he/she can be cured easily. It is really a shocking news for me that the 1/3 world is affected by Tuberculosis. The action has to be taken very fast to cure this.

Gina said...

Toni, your blog is a great idea. Could you please send me the precise reference for the figure from Nat Rev Microbiol ? Would like to find it..