Challenges in assessing transmission of Mycobacterium tuberculosis in long-term-care facilities

In 2012, the Centers for Disease Control and Prevention (CDC) reported 3.2 cases of tuberculosis (TB) per 100,000 persons in the United States.1 Although TB incidence has declined during the past several decades, the 2010 goal of < 1 case per 1,000,000 persons—as established in the national strategic plan for TB elimination—has yet to be achieved.2 Although persons aged ≥ 65 years accounted for only 14% of the population in 2012, this group represented 22% of reported cases of TB.3,4 An analysis of 1993–2008 cases reported in the United States showed that the rate of TB among elderly adults was as much as 30% higher than among younger adults.5 Even more striking are the disproportionate rates documented among those living in long-term-care facilities (LTCFs). Previous reports have estimated that adults aged ≥ 65 years residing in LTCFs may have between 4 and 50 times the risk of developing TB disease than elderly persons living in the community.5–7 As of April 2014, approximately 3.2 million workers were employed in LTCFs.8 The size of this occupational group will grow significantly in the coming years if LTCF resident populations increase as expected. Past estimates suggest the TB case rates are 3 times higher among LTCF workers compared with those working in any other job.9 Therefore, prevention and control of TB in LTCFs are essential to protect both the residents and employees in these settings. The goal of this article is to summarize findings of an LTCF TB outbreak investigation to highlight the unique challenges posed by Mycobacterium tuberculosis transmission in these settings.