The elusive great masquerader: the efficient spread of tuberculosis from a nursing home into the community.

Abstract

Older people represent a somewhat hidden and substantial reservoir of Mycobacterium tuberculosis infection in many nations, including the United States.1 Estimates of mortality from tuberculosis (TB) overall vary widely, but reliable sources report an approximate 2 million to 3 million deaths per year worldwide; projections based on skin-test surveys suggest that up to one-third of the world's population (2 billion people) is currently infected with quiescent but viable tubercle bacilli.2-4 Ijaz et al's study in this issue of the Journal of the American Geriatrics Society5 stresses that TB transmission is very efficient within closed environments, resulting in increased morbidity and mortality; Stead et al.6 have also documented nosocomial spread within such facilities and other closed environments such as prisons and jails. Ijaz et al's article demonstrates the effect of unrecognized TB in a nursing home; the authors have also substantiated the efficient transmissibility of TB from an older source patient with TB disease to healthcare workers and secondary spread to two other nursing homes, a community hospital, and the community. This paper provides emphasis on the importance of strict TB prevention and control measures in facilities providing long-term care to older people in an effort to minimize morbidity and mortality from this treatable illness.7, 8 In their study, the authors evaluate the cause for increased tuberculin skin test (TST) conversion in nursing home employees by tracking the source case using traditional and molecular methods ((1) smears and (2) culture and genotyping, respectively). Furthermore, as also demonstrated, increase TST conversion in one particular location of the long-term care facility must alert healthcare providers to the existence of a likely source case located in that area, necessitating strict TB infection control measures and surveillance techniques. Screening for TB for community-dwelling and institutionalized older people should also include the two-step tuberculin test as part of the initial geriatric assessment to avoid overlooking potentially false-negative reactions.9 Once recognized drug therapy for TB infection (based on TST reactivity criteria) using the newly published latent TB treatment guidelines, substantially reduces the risk of progression of TB infection to TB disease.10-12 (TB infection refers to contained and asymptomatic primary infection with a positive TST reaction; TB disease indicates overt clinical manifestations of TB.) Evaluation for TB disease is indicated for positive TST reactors. (A chest radiograph and prompt recommended therapy should be instituted in documented cases of TB disease.13) Such simple and standard practice can prevent the spread of TB from a source patient to other patients, healthcare providers, and visitors and consequent tertiary spread to other nursing homes, hospitals, and the community, thus reducing unnecessary morbidity and mortality, as this article has effectively shown. The Advisory Committee for the Elimination of Tuberculosis of the Centers for Disease Control and Prevention (CDC) has established guidelines for surveillance, containment, assessment, and reporting of TB infection and disease in long-term care facilities for older people; healthcare professionals, administrators, and staff at such extended care programs must be continually alerted to these recommendations.7, 8 This will in turn tie into the Strategic Plan (updated in 1999) for the elimination of TB in the United States, which includes the necessary actions to meet the CDC goal of elimination of TB by 2010, defined as a case rate of less than one per 1 million population per year.14 In addition, the Institute of Medicine report, Ending Neglect: The Elimination of TB in the US, undertaken with sponsorship from the CDC, reviews the lessons learned from the neglect of TB between the late 1960s and the early 1990s and reaffirms commitment to a more realistic goal of elimination of TB in the United States.15