248259 Case finding during an outbreak of tuberculosis in a homeless shelter − Illinois, 2010

Tuesday, November 1, 2011: 9:20 AM

Julia Howland, MPH , CDC/CSTE Applied Epidemiology Fellow, Illinois Department of Public Health, Chicago, IL
Elaine Darnall, RN, BSN, CIC , Department of Communicable Diseases, Illinois Department of Public Health, Springfield, IL
Michael Arbise, BS(MT)MS , Department of Communicable Diseases, Illinois Department of Public Health, Springfield, IL
Background: Homeless shelters are high-risk settings for tuberculosis transmission and present unique challenges for outbreak control. From November 2009- May 2010, an outbreak of tuberculosis with a matching genotype pattern occurred among residents and staff of a homeless shelter in Illinois.

Methods: Outbreak associated cases were defined as cases with a genotype matching the outbreak strain and an epidemiologic link to the shelter. Culture negative cases with an epidemiologic link to the shelter were also classified as outbreak-associated. Strategies for identifying active cases included mass screenings, alerting of local physicians and laboratories, and ongoing “cough watch” by shelter staff. Direct costs of mass screening events were calculated using billing data and health department records.

Results: Among 760 exposed residents, 18 residents with active tuberculosis were identified. During three mass screenings, 481 residents and 137 staff were evaluated using symptom screen, QuantiFERON Gold in-tube assay, chest x-rays and sputum smear and culture. Sixteen cases had genotype-matched isolates. Two cases were culture negative. Two cases were identified at the screening events, seven through the cough watch and nine in the community. Four-hundred (52.5%) potentially exposed residents did not attend any screening, including two residents later identified as cases. The mass screenings cost approximately $40,000, excluding the cost of sputum testing and staff time.

Conclusion: Difficulty reaching exposed residents, due to transiency and low participation, reduced the yield of mass screening events. In this homeless shelter outbreak, well-informed local providers and symptom screening by shelter staff identified more cases than resource-intensive mass screenings.

Learning Areas:
Protection of the public in relation to communicable diseases including prevention or control

Learning Objectives:
1). Describe an outbreak of tuberculosis in a homeless population, 2). Identify effective techniques for locating cases in a transient population. 3). Discuss the ongoing elevated risk of tuberculosis in the homeless community in the United States

Keywords: Outbreaks, TB

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I participated in the investigation and control of this outbreak and I have training in epidemiology, infectious diseases, outbreak investigation, and community health sciences.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.

See more of: Infectious Disease Epidemiology
See more of: Epidemiology