only test on cdc list., page-10

Around 50% of immigrants have BCG vaccination and come from active TB areas. They usually have poor living conditions, so they are a high risk group.

Another problem is that if the TB becomes active it can be the Drug Resistant TB [DRTB] strain so it is important to test this group to minimise spread.

Additionally, they can be candidates for HIV which with compromised immunity allows TB to become active. In South Africa HIV leading to TB is the direct cause of most deaths.

The Mantoux test is ineffective on these immigrants so a CDC priority area is an effective test.