Transcript Presentation - PHS Commissioned Officers Foundation for the

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)
Background
Captive Elephants in North America
270 Asian elephants
12% have active TB disease
220 African elephants
2% have active TB disease
Tuberculosis in Humans and Elephants
TB
Inactive
Infection
Active
Disease
Treatment
Humans
Elephants
Tuberculosis in Humans and Elephants
TB
Humans
Elephants
Inactive
Infection
Positive TST
Asymptomatic
Non-infectious
Treatment recommended
?
Active
Disease
Treatment
Tuberculosis in Humans and Elephants
TB
Humans
Elephants
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
Tuberculosis in Humans and Elephants
TB
Humans
Elephants
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
Efficacious
?
The Elephant Refuge in Tennessee
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
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
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
Methods
Cohort Study
• Interviews
• Review occupational health records
• TST screening
Onsite Assessment
• Facility design
• Barn management
• Husbandry practices
Outbreak Case Definition
• Refuge employee or intern, 2006–2009
• At least one negative TST, followed by a TST
of ≥5-mm induration
Results
Employee Cohort, 2006–2009
• 46 employees interviewed
– 30 caregivers
– 11 administrators
– 5 maintenance workers
• 9 (20%) had positive TST
– 8 had conversion during 2009
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 2009
8 (89)
5 (14)
20.3 (2.8–146.7)
*Risk estimate not computed when at least one cell contained a zero
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 2009
8 (89)
5 (14)
20.3 (2.8–146.7)
*Risk estimate not computed when at least one cell contained a zero
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 2009
8 (89)
5 (14)
20.3 (2.8–146.7)
*Risk estimate not computed when at least one cell contained a zero
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 2009
8 (89)
5 (14)
20.3 (2.8–146.7)
*Risk estimate not computed when at least one cell contained a zero
TST Conversion Timeline Among
Quarantine Facility Employees, 2009
TST Conversion Timeline Among
Quarantine Facility Employees, 2009
Quarantine Facility
Quarantine Facility
Elephant with TB
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)
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)
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)
Observation:
Delay in Recognizing Increased Risk
Observation:
Delay in Recognizing Increased Risk
Observation:
High Risk Practices
Observation:
Unrestricted Air Flow
Conclusions
Findings
• Zoonotic Mtb transmission from an elephant
to humans
• Insufficient infection control
– Inconsistent use of respirators
– Aerosol generating procedures
– Unrestricted air flow
Limitations
• Small study population
• 11 employees not contacted
• Formal air flow studies pending
Recommendations
• Relocate nonessential personnel
• Increase use of respirators
• Revise infection control practices
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.