Prevalence and evolution of Mycobacterium tuberculosis infection in tuberculosis case contacts

INTRODUCTION : The tuberculin test is a diagnostic method for detecting latent tuberculosis (TB) infection, especially among disease contact cases. The objective of this study was to analyze the prevalence and evolution of Mycobacterium tuberculosis infection among TB contact cases. METHODS : A retrospective cohort study was performed in a reference center for TB. The study population consisted of 2,425 patients who underwent a tuberculin test from 2003 to 2010 and whose results indicated contact with individuals with TB. The data were collected from the registry book of the tuberculin tests, patient files and the Information System Records of Notification Grievance. To verify the evolution of TB, case records through September 2014 were consulted. Data were analyzed using the Statistical Package for the Social Sciences (SPSS). In all hypothesis tests, a significance level of 0.05 was used. RESULTS : From the studied sample, 435 (17.9%) contacts did not return for reading. Among the 1,990 contacts that completed the test, the prevalence of latent TB infection was 35.4%. Of these positive cases, 50.6% were referred to treatment; the dropout rate was 42.5%. Among all of the contacts, the TB prevalence was 1.8%, from which 13.2% abandoned treatment. CONCLUSIONS : The collected data indicate the need for more effective public policies to improve TB control, including administering tests that do not require a return visit for reading, enhancing contact tracing and encouraging actions that reinforce full treatment adherence.

研究背景：结核菌素试验（tuberculin test）是检测潜伏性结核（TB, Tuberculosis）感染的诊断手段，尤其适用于结核病接触人群。本研究旨在分析结核病接触者群体中结核分枝杆菌（Mycobacterium tuberculosis）感染的流行率与演变特征。
研究方法：本研究于一所结核病诊疗参考中心开展回顾性队列研究。研究对象为2003年至2010年间接受结核菌素试验、且检测结果提示存在结核病接触史的2425名患者。研究数据来源于结核菌素试验登记手册、患者病历档案以及传染病通报申诉信息系统记录。为验证结核病的病情演变情况，本研究查阅了截至2014年9月的病例记录。数据分析采用社会科学统计软件包（SPSS, Statistical Package for the Social Sciences）完成，所有假设检验均以0.05作为显著性水平。
研究结果：本次纳入的研究样本中，共有435名（17.9%）接触者未返回进行结果判读。在完成全部试验流程的1990名接触者中，潜伏性结核感染的流行率为35.4%。其中50.6%的阳性病例被转诊接受规范治疗，治疗失访率达42.5%。在所有纳入研究的接触者中，活动性结核病的流行率为1.8%，该群体中13.2%的患者出现治疗中断情况。
研究结论：本次收集的数据表明，亟需制定更有效的公共卫生政策以强化结核病防控工作，包括推广无需返回现场判读结果的结核检测技术、加强接触者追踪管理，以及开展各类宣教与支持行动以提升患者全程治疗依从性。