Figure 4.

Schematic representation of the living environment of five secondary cases and index cases. In the first round of screening, we identified two individuals with LTBI who shared a room with the index patient, one of whom received prophylaxis because of a strongly positive PPD and IGRA(+). In the second round of screening, we identified 5 close contacts who developed ATB (secondary cases), including case 2, case 3, case 4, case 5, and case 6. Interestingly, case 3, case 4, and case 5 lived in the same dormitory (Room B) with the index case, and case 2 (Room A) and case 6 (Room C) were close friends who did not live in the same dormitory with the index case.