It doesn't differentiate between active and latent disease.

它并不能区分活跃期还是潜伏期。

After doing a screening test with PPD or IGRA, anyone with a positive result typically gets a chest x-ray to look for signs of active TB disease.

在做了PPD或者IGRA的筛查实验后，任何有阳性结果的人员都应该去做一个X线胸片，以探寻是否有TB在体内活跃的表现。