Table 2. Tuberculosis incidence by subgroup of subjects defined by detection method and eligibility for chemoprophylaxis by exposureg roup.*.
| Subgroup of subjects (defined by detection method and eligibility for chemoprophylaxis) | Number of subjects observed |
Subjects who developed tuberculosis |
Number of bacteriologically positive cases |
||
| Number | % of the subjects observed |
||||
| Group 1 | |||||
| Subjects with tuberculosis diagnosed before having the contact investigation | 1 | 1 | 100 | 0 | |
| Subjects who had the contact investigation | Subjects with tuberculosis diagnosed in the contact investigation | 6 | 6 | 100 | 2 |
| Subjects who were eligible for and completed chemoprophylaxis | 19 | 2 | 10.5 | 1 | |
| Subjects who were eligible for and did not complete chemoprophylaxis | 1 | 0 | 0 | 0 | |
| Subjects who were not required to receive chemoprophylaxis | 3 | 0 | 0 | 0 | |
| Total | 30 | 9 | 30.0 | 3 | |
| Group 2 | |||||
| Subjects with tuberculosis diagnosed before having the contact investigation | 1 | 1 | 100 | 0 | |
| Subjects who had the contact investigation | Subjects with tuberculosis diagnosed in the contact investigation | 2 | 2 | 100 | 0 |
| Subjects who were eligible for and completed chemoprophylaxis | 40 | 0 | 0 | 0 | |
| Subjects who were eligible for and did not complete chemoprophylaxis | 1 | 0 | 0 | 0 | |
| Subjects who were not required to receive chemoprophylaxis | 28 | 3 | 10.7 | 1 | |
| Total | 72 | 6 | 8.3 | 1 | |
| Group 3 | |||||
| Subjects with tuberculosis diagnosed before having the contact investigation | 0 | - | - | - | |
| Subjects who had the contact investigation | Subjects with tuberculosis diagnosed in the contact investigation | 0 | - | - | - |
| Subjects who were eligible for and completed chemoprophylaxis | 43 | 1 | 2.3 | 0 | |
| Subjects who were eligible for and did not complete chemoprophylaxis | 4 | 1 | 25.0 | 1 | |
| Subjects who were not required to receive chemoprophylaxis | 57 | 3 | 5.3 | 2 | |
| Total | 104 | 5 | 4.8 | 3 | |
| Group 4 | |||||
| Subjects with tuberculosis diagnosed before having the contact investigation | 0 | - | - | - | |
| Subjects who had the contact investigation | Subjects with tuberculosis diagnosed in the contact investigation | 1 | 1 | 100 | 0 |
| Subjects who were eligible for and completed chemoprophylaxis | 35 | 0 | 0 | 0 | |
| Subjects who were eligible for and did not complete chemoprophylaxis | 1 | 1 | 100 | 1 | |
| Subjects who were not required to receive chemoprophylaxis | 323 | 2 | 0.6 | 1 | |
| Total | 360 | 4 | 1.1 | 2 | |
| All groups | |||||
| Subjects with tuberculosis diagnosed before having the contact investigation | 2 | 2 | 100 | 0 | |
| Subjects who had the contact investigation | Subjects with tuberculosis diagnosed in the contact investigation | 9 | 9 | 100 | 2 |
| Subjects who were eligible for and completed chemoprophylaxis | 137 | 3 | 2.2 | 1 | |
| Subjects who were eligible for and did not complete chemoprophylaxis | 7 | 2 | 28.6 | 2 | |
| Subjects who were not required to receive chemoprophylaxis | 411 | 8 | 1.9 | 4 | |
| Total | 566 | 24 | 4.2 | 9 | |
*: Group 1, homeroom classmates; Group 2, students who shared special classes or extracurricular activities with the case; Group 3, third-grade students after excluding those who belonged to exposure group 1 and group 2; Group 4, first- or second-grade students after excluding those who belonged to exposure group 2.