Muecke C, Isler M, Menzies D, Allard R, Tannenbaum T N, Brassard P
Department of Public Health, McGill University Health Centre, Montreal, Quebec, Canada.
Int J Tuberc Lung Dis. 2006 May;10(5):530-5.
A 25-year-old university student was diagnosed with cavitary pulmonary and laryngeal tuberculosis following symptoms of underlying cough of 6 months' duration.
To estimate the hourly risk of infection (HRI) and examine the role of environmental factors, including room size and ventilation, in modulating this risk.
Contact investigation.
Of 1100 contacts identified, 78.3% (n = 896) received a tuberculin skin test (TST), of whom 27.5% had a positive result. Among 634 Canadian-born contacts tested, 22.7% had a positive TST. The independent risk factors for a positive TST among Canadian-born university students were: > 35 h spent with the index case (adjusted OR 6.6, 95% CI 1.0-44.9) and smaller classroom size (aOR 5.0, 95% CI 1.4-10.0). In the first school term, the HRI among Canadian-born student contacts was 0.9%; in the second term, it was 1.6%.
There are inherent limitations in generalising findings from an outbreak investigation, due to the considerable variation in the infectiousness of cases. Nevertheless, in situations where the index case has a high degree of infectiousness, and there are numerous contacts with low expected prevalence of infection, the HRI can, together with ventilation measurements, be useful in guiding the extent of contact investigation needed.
一名25岁的大学生在出现持续6个月的潜在咳嗽症状后，被诊断为空洞性肺结核和喉结核。
估计每小时感染风险（HRI），并研究环境因素，包括房间大小和通风，在调节这种风险中的作用。
接触者调查。
在确定的1100名接触者中，78.3%（n = 896）接受了结核菌素皮肤试验（TST），其中27.5%结果呈阳性。在634名在加拿大出生的接受检测的接触者中，22.7%的TST呈阳性。在加拿大出生的大学生中，TST呈阳性的独立风险因素为：与索引病例相处时间> 35小时（调整后的OR为6.6，95% CI为1.0 - 44.9）以及教室规模较小（aOR为5.0，95% CI为1.4 - 10.0）。在第一学期，在加拿大出生的学生接触者中的HRI为0.9%；在第二学期，为1.6%。
由于病例传染性存在相当大的差异，疫情调查结果的推广存在固有局限性。然而，在索引病例传染性高且接触者众多但预期感染患病率低的情况下，HRI连同通风测量结果，可有助于指导所需接触者调查的范围。
