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Outbreak of Mycobacterium tuberculosis Among Employees of an Elephant Refuge Rendi Murphree, PhD CDR, USPHS Tennessee Department of Health EIS Field Assignments.

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Presentation on theme: "Outbreak of Mycobacterium tuberculosis Among Employees of an Elephant Refuge Rendi Murphree, PhD CDR, USPHS Tennessee Department of Health EIS Field Assignments."— Presentation transcript:

1 Outbreak of Mycobacterium tuberculosis Among Employees of an Elephant Refuge Rendi Murphree, PhD CDR, USPHS Tennessee Department of Health EIS Field Assignments Branch, DAS (proposed), SEPDPO (proposed)

2 Background

3 Captive Elephants in North America 270 Asian elephants 12% have active TB disease 220 African elephants 2% have active TB disease

4 Tuberculosis in Humans and Elephants TBHumansElephants Inactive Infection Active Disease Treatment

5 Tuberculosis in Humans and Elephants TBHumansElephants Inactive Infection Positive TST Asymptomatic Non-infectious Treatment recommended ? Active Disease Treatment

6 Tuberculosis in Humans and Elephants TBHumansElephants Inactive Infection Positive TST Asymptomatic Non-infectious Treatment recommended ? Active Disease Sputum or chest X-ray Symptomatic Infectious Treatment required Respiratory secretions Rarely symptomatic Infectious Treatment difficult Treatment

7 Tuberculosis in Humans and Elephants TBHumansElephants Inactive Infection Positive TST Asymptomatic Non-infectious Treatment recommended ? Active Disease Sputum or chest X-ray Symptomatic Infectious Treatment required Respiratory secretions Rarely symptomatic Infectious Treatment difficult TreatmentEfficacious ?

8 The Elephant Refuge in Tennessee

9 Elephant Refuge South-central Tennessee Founded in 1995 Care of sick, old, abused or needy elephants Nonprofit organization accredited, regulated and closed to the public

10 Elephant Refuge 2700 acres with 3 distinct areas – 2 African elephants – 6 Asian elephants 1 “cured” of TB disease in 2006 – 7 Asian elephants All quarantined since 2006 for exposure to TB disease

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13 The Outbreak Notification – October, 2009 – 5 tuberculin skin test (TST) conversions among employees of the refuge Investigation objectives – Determine extent of outbreak – Identify risk factors for TST conversion in humans – Prevent ongoing transmission

14 Methods

15 Cohort Study Interviews Review occupational health records TST screening

16 Onsite Assessment Facility design Barn management Husbandry practices

17 Outbreak Case Definition Refuge employee or intern, 2006–2009 At least one negative TST, followed by a TST of ≥5-mm induration

18 Results

19 Employee Cohort, 2006– employees interviewed – 30 caregivers – 11 administrators – 5 maintenance workers 9 (20%) had positive TST – 8 had conversion during 2009

20 Risk Factors for TB Among Refuge Employees, 2006–2009 Case (n = 9) No. (%) Noncase (n = 37) No. (%) Relative Risk (95% CI) Foreign-born 2 (22) 4 (11)0.5 (0.1–2.0) International travel in last 5 years 5 (56) 14 (38)1.8 (0.6–5.8) Exposure to person(s) with tuberculosis 0 ( 0) 4 (11)* Previous healthcare facility work 1 (11) 7 (19)0.6 (0.1–4.1) Previous correctional facility live/work 0 (0) 4 (11)* Previous homeless shelter live/work 0 (0) 1 ( 3)* Close contact with elephant(s) 2 (22) 9 (24)0.9 (0.2–3.8) Quarantine facility exposure in (89) 5 (14)20.3 (2.8–146.7) *Risk estimate not computed when at least one cell contained a zero

21 Risk Factors for TB Among Refuge Employees, 2006–2009 Case (n = 9) No. (%) Noncase (n = 37) No. (%) Relative Risk (95% CI) Foreign-born 2 (22) 4 (11)0.5 (0.1–2.0) International travel in last 5 years 5 (56) 14 (38)1.8 (0.6–5.8) Exposure to person(s) with tuberculosis 0 ( 0) 4 (11)* Previous healthcare facility work 1 (11) 7 (19)0.6 (0.1–4.1) Previous correctional facility live/work 0 (0) 4 (11)* Previous homeless shelter live/work 0 (0) 1 ( 3)* Close contact with elephant(s) 2 (22) 9 (24)0.9 (0.2–3.8) Quarantine facility exposure in (89) 5 (14)20.3 (2.8–146.7) *Risk estimate not computed when at least one cell contained a zero

22 Risk Factors for TB Among Refuge Employees, 2006–2009 Case (n = 9) No. (%) Noncase (n = 37) No. (%) Relative Risk (95% CI) Foreign-born 2 (22) 4 (11)0.5 (0.1–2.0) International travel in last 5 years 5 (56) 14 (38)1.8 (0.6–5.8) Exposure to person(s) with tuberculosis 0 ( 0) 4 (11)* Previous healthcare facility work 1 (11) 7 (19)0.6 (0.1–4.1) Previous correctional facility live/work 0 (0) 4 (11)* Previous homeless shelter live/work 0 (0) 1 ( 3)* Close contact with elephant(s) 2 (22) 9 (24)0.9 (0.2–3.8) Quarantine facility exposure in (89) 5 (14)20.3 (2.8–146.7) *Risk estimate not computed when at least one cell contained a zero

23 Risk Factors for TB Among Refuge Employees, 2006–2009 Case (n = 9) No. (%) Noncase (n = 37) No. (%) Relative Risk (95% CI) Foreign-born 2 (22) 4 (11)0.5 (0.1–2.0) International travel in last 5 years 5 (56) 14 (38)1.8 (0.6–5.8) Exposure to person(s) with tuberculosis 0 ( 0) 4 (11)* Previous healthcare facility work 1 (11) 7 (19)0.6 (0.1–4.1) Previous correctional facility live/work 0 (0) 4 (11)* Previous homeless shelter live/work 0 (0) 1 ( 3)* Close contact with elephant(s) 2 (22) 9 (24)0.9 (0.2–3.8) Quarantine facility exposure in (89) 5 (14)20.3 (2.8–146.7) *Risk estimate not computed when at least one cell contained a zero

24 TST Conversion Timeline Among Quarantine Facility Employees, 2009

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26 Quarantine Facility Quarantine Barn Admin Area

27 Quarantine Barn Admin Area Quarantine Facility Elephant with TB

28 Characteristics of Quarantine Facility Employees, 2009 Case (n = 8) No. (%) Noncase (n = 5) No. (%) Position Caregiver Administrative Maintenance 5 (63) 3 (38) 0 ( 0) 3 (60) 0 ( 0) 2 (40) Close contact with elephant(s) 1 (13) 2 (40) Participated in elephant(s) trunk wash 0 ( 0) 1 (20) Pressure washed 5 (63) 3 (60) Annual N95 fit testing 2 (25) 3 (60) “Always” compliant with N95 wear 2 (25) 3 (60)

29 Characteristics of Quarantine Facility Employees, 2009 Case (n = 8) No. (%) Noncase (n = 5) No. (%) Position Caregiver Administrative Maintenance 5 (63) 3 (38) 0 ( 0) 3 (60) 0 ( 0) 2 (40) Close contact with elephant(s) 1 (13) 2 (40) Participated in elephant(s) trunk wash 0 ( 0) 1 (20) Pressure washed 5 (63) 3 (60) Annual N95 fit testing 2 (25) 3 (60) “Always” compliant with N95 wear 2 (25) 3 (60)

30 Characteristics of Quarantine Facility Employees, 2009 Case (n = 8) No. (%) Noncase (n = 5) No. (%) Position Caregiver Administrative Maintenance 5 (63) 3 (38) 0 ( 0) 3 (60) 0 ( 0) 2 (40) Close contact with elephant(s) 1 (13) 2 (40) Participated in elephant(s) trunk wash 0 ( 0) 1 (20) Pressure washed 5 (63) 3 (60) Annual N95 fit testing 2 (25) 3 (60) “Always” compliant with N95 wear 2 (25) 3 (60)

31 Observation: Delay in Recognizing Increased Risk

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33 Observation: High Risk Practices

34 Observation: Unrestricted Air Flow

35 Conclusions

36 Findings Zoonotic Mtb transmission from an elephant to humans Insufficient infection control – Inconsistent use of respirators – Aerosol generating procedures – Unrestricted air flow

37 Limitations Small study population 11 employees not contacted Formal air flow studies pending

38 Recommendations Relocate nonessential personnel Increase use of respirators Revise infection control practices

39 Acknowledgments Elephant refuge employees and leadership Tennessee Wildlife Regulatory Authority – Walter Cook TN South-central Regional Health Office – Lang Smith, MD – Joy Smith, RN Lewis County Health Department Tennessee Department of Health – John R. Dunn, DVM, PhD – Jon V. Warkentin, MD, MPH – Timothy F. Jones, MD Vanderbilt University School of Medicine – William S. Schaffner, MD CDC – W. Randolph Daley, DVM, MPH The findings and conclusions in this report are those of the author and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

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