Factor/Category (index cases) Incidence of infection (contacts) Test
No. tested ***Infected (%)
Sex Male 348 48(13.8) NS
  Female 265 40(15.1)
Age -39 304 34(11.2) NS
  40-59 190 35(18.4)
  60- 119 19(16.0)
*Chest X-ray Lung area Unilateral 269 34(12.6) NS
  Bilateral 341 54(15.8)
Cavity Absent 254 26(10.2) P＜0.05
  Present 356 62(17.4)
Extent 1 60 5(8.3) NS
  2 407 58(14.3)
  3 143 25(17.5)
Grade of smear positivity 1+ 45 4(8.9) P＜0.05
  2+ 297 35(11.8)
  3+ 271 49(18.1)
**Duration of cough Less than 2 months 261 33(12.6) NS
  2 months or over 348 55(15.8)
         
Total 　 613 88(14.4) 　

*Laryngeal tuberculosis; 2 cases, **Unknown duration of cough; 2 cases ***Infected; Positive-QFT case, non-infected; Negative-QFT case
Table 3: Incidence of infection according to the related factors.