What on earth IS the BCG??

This is one of the burning questions you will have when looking over your child's immunization record. The BCG is a vaccination for tuberculosis given to babies to help prevent tuberculosis. Tuberculosis itself is a very common and difficult to treat infection spread by coughing, usually involving the lungs but occasionally spreading out to the brain and other organs-- it is one of the number one killers of all time and is particularly dangerous in young children who are even more likely to have it spread out of the lungs if they are malnourished. China is on the WHO (World Health Organization) top 20 lists of countries where tuberculosis is most common.

The BCG is given to prevent any infection from getting out of the lungs and causing the worst types of TB infections in infants. The immunization itself is a live weakened TB bacteria and the children are immunized as infants. In most cases if the child was immunized, you will see a small round scar on their left or right upper outer arm. It protects 80 out of 100 children from TB spreading out of the lungs but isn’t particularly effective at preventing the lung version of TB. 

Young children have weak immune systems and so the effectiveness of BCG wears off with time which then means the child may get lung TB even though they have had the vaccine. In older children and adults here in the US, physicians perform skin testing to see if someone has been exposed to TB. This is done by injecting a small amount of tuberculin (PPD) under the skin and measuring the size of the bump, not the red area at the site in 48-72 hours. All of you adoptive parents had this done for your initial medicals for your dossiers.

If the test is positive we usually follow this with a chest X-ray to see if there is any evidence of TB in the lungs hibernating (called latent infection). In addition, all children at least two years old in China are tested for TB with this skin test before the US consulate can issue a visa. This requires an additional 2-3 days in Guangzhou waiting for the PPD to be read. If the PPD is positive, a chest xray will be required, and this is a US government requirement. It's a good requirement. It protects you, the parents, and your children and everyone one else on the plane breathing the same recycled air for 14 hours.

What confuses things further is that the BCG, because it is tuberculosis, can cause the skin testing for TB  to be positive even if the child doesn’t have real TB! If a child is coming from an area like China where TB is so common and tests positive with the skin test they are assumed to have been exposed and possibly have lung TB and will be required to get the X-ray. The assumption is that the BCG has worn off,  the child was exposed to TB, and has possible become infected.
What if my child had the BCG, had a PPD test and it is negative? Does she have TB? Not likely. The immunity from the BCG has worn off and your child has not been exposed to TB. Exceptions would be if they are very malnourished or the test was interpreted wrong.

What if the PPD is positive? Should she have a PPD in the future? No. Once it is positive, it is considered positive forever and retesting can cause a severe reaction at the test site.

Stay tuned for further discussions of treatment.