Dose-response relationship between treatment delay of smear-positive tuberculosis patients and intra-household transmission: a cross-sectional study.
In order to document the effect of treatment delay on tuberculosis (TB) latent infection among the household contacts of TB patients, a cross-sectional TB infection prevalence survey was conducted among household contacts in Yunnan Province, southern China. In total, 1360 household contacts of 393 smear-positive pulmonary TB patients were enrolled, together with 308 household contacts of 90 non-TB patients. Using the contacts of non-TB patients as the baseline of TB infection, there was a dose-response relationship between household infection and delay of TB treatment (TB infection prevalence 9.7, 7.8, 19.9, 25.7 and 26.9% for non-TB case, TB case with delay < or =30 d, 30-60 d, 60-90 d and >90 d, respectively). Older age, TB index patient with lung cavitation, and sleeping in the same bedroom with a TB patient were all associated with an increased risk of being tuberculin-skin-test positive. In conclusion, 30 d delay in treatment seems to be the turning point at which a significant increase in risk for TB infection occurs. Apart from conventional indicators, magnitude of treatment delay should be considered as a performance indicator for TB control programmes in high-TB-burden countries. Measures for the detection of early cases should be intensified.
Lin
Xu
X
Yunnan Provincial Centers for Disease Control and Prevention, Yunnan, China. xulinth@hotmail.com
Chongsuvivatwong
Virasakdi
V
Lin
Lu
L
Geater
Alan
A
Lijuan
Ren
R
D000328:Adult; D017677:Age Distribution; D002681:China; D016358:Contact Tracing; D003430:Cross-Sectional Studies; D004305:Dose-Response Relationship, Drug; D042241:Early Diagnosis; D005191:Family Characteristics; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D012307:Risk Factors; D012959:Socioeconomic Factors; D013183:Sputum / Q000382:microbiology; D013997:Time Factors; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy / Q000635:transmission