1. Tuberculosis Among Thai
Healthcare Workers:
a Human or System Failure
Anucha Apisarnthanarak, M.D.
Assistant Prof.
Thammasat University Hospital
anapisarn@yahoo.com
Adjunct Visiting Prof.
Washington University School of Medicine, USA

2. Objectives
 Case presentation
 Is this a human error?
 Is this a system error?
 How to develop intervention to reduce TB
transmission in resource limited setting

3. An ICN notified you that one OR
nurse had been admitted for
active tuberculosis
She had SLE and on
prednisone for the past 3
months. She had been
contacting to her roommate
and others OR nurses. Her
symptoms of coughing
persisted for the past 3 weeks.

4. What will you do next?
A) Leave it alone
B) Contact tracing and give INH for all contacts
C) Contact tracing and give INH for those who
had positive PPD
D) Contact tracing, double steps PPD, repeat in
the next 3 months, and gave INH for those who
had evidence of recent converter
E) I am not sure what to do

5. Transmission

7. Arguing for not doing PPD
skin test
 Difficult to educate physicians to perform
CXR prior to INH prescription
 Lack of specificity
 INH resistant incidence is high (12-15%)
 Benefit may wane after 5 years
 Etc.

8. What we did?

9. Postexposure Detection of Mycobacterium
tuberculosis Infection in Health Care
Workers in Resource-Limited Settings
No. (%) of patients
Second TST With
M.turberculosi
Increase of s infection at 2-
Initial TST Initial TST No change >10 mm year follow-up
reaction size (n = 95) (n = 87) (n = 8) (n = 6)
> 15 mm 20 (21) 18 (21) 2 (25) 2 (33)
10-15 mm 65 (68) 63 (72) 2 (25) 1 (17)
No reaction 10 (10) 6 (7) 4 (50) 3 (50)
Apisarnthanarak A, et al. Post-exposure detection of TB in Thai HCWs. CID, 2008

10. Influence of Bacille Calmette-Guerin Vaccination on
Size of Turculin Skin Test Reaction: To What Size?
Tissot, et al. Service of Infectious Diseases, University Hospital,Lausanne, Switzerland.
Clin Infect Dis, 2004

11. Among Thai HCWs and in
other resource-limited settings
Khawcharoenporn T, Apisarnthanarak A, et al. TST among MS with prior BCG. ICHE, 2008 (in press)

12. Among HCWs around the world
Study TB case TST BCGV effect
location rate per Definition BCGV reactions
Effect on 1st step TST Booster effect on 2nd step
year 100,000 of BCGV rate 10 mm. positivity TST
Brazil, 2001 62 BCGV scars 70% 57% Yes, at cut-off level 10 mm. Yes, for  6 mm. increase
Chile, 1990 ND BCGV scars 84% 48% Yes, at cut-off level 10 mm. Yes, for  6 mm. increase
Israel, 1997 10 Recall 63% 60% No, at cut-off level 10 mm. Yes, for  6 mm. increase
Ivory Coast, 172 BCGV scars 83% 79% No, at cut-off level 10 mm. ND
1997 and recall
Malaysia, 66 Recall 99% 78% No, at cut-off level 10 ND
2001 and 15 mm.
Mexico, 52 BCGV scars 84% 64% Yes, at cut-off level 10 mm. ND
1998
Thailand, 64 BCGV scars 77% 68% Yes, at cut-off level 10 mm. ND
1996 No, at cut-off level 15 mm.
Turkey, 96 BCGV scars 93% 83% Yes, at cut-off level 10 mm. ND
2002 and recall
Uganda, 402 BCGV scars 41% 57% No, at cut-off level 10 mm. ND
2001
Our study 85 BCGV scars 58% 62% Yes,at cut-off level10-19mm. Yes, for 6-9 mm. increase
No, at cut-off level 20 mm. No, for  10 mm. increase
Khawcharoenporn T, Apisarnthanarak A, et al. TST among MS with prior BCG. ICHE, 2008 (in press)

13. Given the experience with
Avian Influenza, do HCWs in
your hospital comply with
isolation precaution and use of
PPE for TB?
A) Yes
B) No
C) Maybe

14. Impact of Knowledge
and Positive Attitude
About H5N1 on Infection
Control Practices For
Airborne Diseases
Among Thai HCWs
Apisarnthanarak A, et al.
Infect Control Hosp Epidemiol, 08

15. Do our HCWs lack of knowledge
and awareness for TB?
 Knowledge & Practices
 98% of HCWs had good knowledge on
AI prevention.
 Only 33% follow all appropriate IC
protocol for other airborne diseases.

16. Teaching Point
“Good knowledge doesn’t always translate
into good IC practices and
behaviors…additional interventions are
needed”

17. Is this a system error?
7000 Laboratory
6977
Medicine
ED/ICU
Rate per 100,000 HCWs
All hospital
Other areas
2000
1500 1418
1163
1000 932
709
792
709 581
709
500 488 466
233
334
187
60 187 121
0 181
1994 1995 1996 1997
Year
Alonso-Echanove, et al. TB among HCWs in Peru. CID, 2002

18. Evaluation of potential risk factors for Mycobacterium
tuberculosis infection among health care workers
(HCWs) from clinical and laboratory areas
Clinical areas Laboratory areas
n/N PRR P n/N PRR P
Variable (95% Cl) (95% Cl)
Employment in medicine 92/121 2.1(1.5-2.9) <.001 _ _ _
wards
Helped in sputum 57/71 1.5(1.2-1.9) <.001 1/1 _ NS
collection
Contact with person with 106/142 3.2(1.9-5.3) <.001 34/39 1.9(1.3-2.7) <.001
active tuberculosis
Duration of 102/156 1.5(1.0-2.2) .01 37/52 1.2(0.8-1.8) NS
employment≥1 year
Use of common staff 106/171 1.1(0.8-1.7) NS 41/46 2.7(1.6-4.5) .001
areas

20. Teaching Point
“TB is most likely to be transmitted
when health care workers and
patients come in contact with
patients who have unsuspected TB
disease, who are not receiving
adequate treatment, and who have
not been isolated from others.”

21. How to develop
intervention to reduce
TB transmission in
resource limited
setting?

22. How to develop intervention to
reduce TB transmission in resource
limited setting?
Hierarchy of Infection Controls
 Work Practice and Administrative Controls are policies
and practices to reduce risk of exposure, infection, and
disease
 Environmental Controls are equipment or practices to
reduce the concentration of infectious bacilli in air in
areas where contamination of air is likely
 Respiratory Protection is used to protect personnel who
must work in environments with contaminated air

23. Components of TB
Infection Control Plan
 Screen clients to identify persons with symptoms of TB
disease or on treatment for current TB
 Educate on TB in general and on cough hygiene; provide
face masks or tissues to symptomatic (suspect) or known
cases
 Expedite TB suspect/case receipt of services
 Investigate on site or refer TB diagnostic services and
treatment

24. Pathway for avian influenza
is well established

25. Components of TB
Infection Control Plan (2)
 Use and maintain environmental control measures
 Train and motivate staff to recognize TB disease in
themselves
 Train and educate staff on TB and the TB infection
control plan
 Monitor and improve plan’s implementation

26. Don’t be bias: Thailand is
a model country for WHO
TB intervention campaign

28. Environmental Control
Measures
 Goal: reduce droplet nuclei containing
M. tuberculosis in the air
 Means: maximize controlled natural ventilation
 Design of waiting areas, special exam rooms
for those with symptoms
 Fans and fixed open windows and doors

29. Environmental Controls
 Ventilation (natural and mechanical)
 Filtration
 Upper room UVGI (but expensive and less effective
when humidity >70%)
 Optimal use of interior space (also an admin issue)
 Perform sputum-induction procedures outside or in
special ventilated booths

30. Natural Ventilation
Door
Air Mixing and Directional Flow

31. Direction of Natural Ventilation or Incorrect
Working Locations
Direction of Natural Ventilation or Correct
Working Locations

32. However, wind direction may
not be predictable all the time
Natural Ventilation
Stack pressure driving air flow

33. Evaluate Infection Control (IC)
Interventions and Measure Impact!!!
 Periodic observation of IC practices
 Analyze HCW surveillance data
 Environmental interventions testing
 Chart reviews and audits
 Time intervals
 Admission to TB suspicion, AFB smears,
sputum collection, laboratory reporting,
initiation of treatment

35. Naturally ventilated
Airborne Precautions Room
Open window(100%) + Open door 29.3-93.2 ACH
Open window(100%) + Closed door 15.1-31.4 ACH
Open window(50%) + Closed door 10.5-24 ACH
Open window + Open door 8.8 ACH
Y. Li et al. J Hosp Infect. In press.

36. Measurement of Natural Ventilation
CO2 release Windows & doors opened
6000
5000
CO2 concentration
4000
(ppm)
Slow CO2 concentration decay Rapid decay with
3000 with windows closed: 0.5 windows open:
air-changes/hour 12 air-changes/hour
2000
1000
0
5 10 15 20 25 30 35
Time (minutes)
Escombe AR, et al. PloS Med 2007;4:e68

37. Measurement of Natural Ventilation
10000
8000 Windows & doors:
Absolute ventolation m3/h
Fully closed
6000
Partially open
Fully open
4000
2000
0
Low wind Wind
2 km/h >2 km/h
Mechanical
Natural ventilation ventilation
Escombe AR, et al. PloS Med 2007;4:e68

38. Pitfalls in Environmental Control
Setting 1 : Inpatient Chest Disease
Ward
Mixing Fan Window detail

39. Pitfalls in Environmental Control
Setting 1 : Inpatient Chest Disease
Strengths
Excellent Mixing fans can help Window area approx
potential for disperse aerosols in 10 m2 on each side
cross-ventilation when wind is still
Patient wearing
mask to reduce
aerosol generation

40. Pitfalls in Environmental Control
Setting 1 : Inpatient Chest Disease
Weaknesses
Window potential under-
utilized. Only 5% of floor
area on each side.
What happens at night?
Shutters closed =
zero ventilation

41. Modified “negative-pressure”
during SARS
 Exhaust fan was mounted in room
 Unilateral air flow from nursing area into
room
 Smoke test and ajar door test

42. Exhaust fan mounted on panel
inside the room to create a
negative pressure
Air was sucked out from
nurse station through the room
Door ajar due to
negative pressure
Single air conditioner per room

43. Respiratory Protection
Sneeze without a Sneeze with a
surgical mask surgical mask
Granville-Chapman, J et al. BMJ 2007;335:1293
Copyright ©2007 BMJ Publishing Group Ltd.

44. Impact of TB Infection Control Measures on
TB Transmission in Chiang Rai, Thailand,
1995 - 1999
TB infection control measures implemented (1996)
 Administrative
 Infection control plan and SOPs
 HCW TST testing, with isoniazid preventive therapy
 TB patient education and training for HCW (including lab staff)
 Environmental
 Natural ventilation maximized in high-risk areas
 Negative pressure ventilation in TB isolation rooms
 Class II biosafety cabinet for laboratory
 HCW respiratory protection (N-95 masks)
 Known exposure to infectious TB patient
 Laboratory staff processing TB cultures
TB rate: 9.3/100 HCWs (1995-1997) to 2.2/100 HCWs (1998-1999)
Yanai H, Limpakarnnanarat K, Uthaivoravit W, et al. Int J Tuberc Lung Dis 2003;7:36-45.

45. Conclusions
 TB among HCWs occurred from a combination
of human error and system error
 Education to raise HCWs awareness doesn’t
always associated with improved IC behaviors
 Although controversial, use of PPD skin test
with different cut point might be applicable after
post-exposure prophylaxis
 Administrative control, respiratory control and
respiratory protection can be readily applicable
to control TB in developing countries

46. Thank you very much for
your attention
“Kob-Koon-Krub”
ขอบคุณครับ

47. Factors Affecting the
Transmission of Tuberculosis
Patient Environmental Contact
CASE CONTACT
Site of TB Ventilation Closeness and
Cough Filtration duration of contact
Bacillary load U.V. light Immune status
Treatment Previous infection

48. Post-exposure management
 PPD, CXR after exposure
 If positive PPD, negative CXR repeat another
PPD in 12 weeks
 If positive PPD, positive CXR rule out active
diseases
 If PPD negative, CXR positive rule out active
diseases
 If PPD negative, CXR negative repeat another
PPD in 12 weeks

49. Post-exposure management
 For Those with 2nd PPD positive
 CXR to rule out active disease
 If CXR negative, will offer INH for treatment of
latent infection
 For Those with 1st & 2nd PPD positive
 Depends on the size of PPD test, may offer
treatment for latent infection

50. Work Practice and
Administrative Controls
 Prompt recognition and separation of persons with
infectious TB
 Prompt provision of TB and other services (esp HIV,
including HCW)
 Infection control plan, including administrative support and
quality assurance
 Staff training
 Coordination of care
 Patient education (cough etiquette; “Ward cough officer”)

51. Environmental Controls
Natural Ventilation
Free flow of ambient air in and out
through open windows
Negative Pressure Room
Illustrates airflow from outside a room,
across patients’ beds and exhausted
out the far side of the room

52. Ventilation rates in a
naturally/hybrid- ventilated room
under different test conditions
The door connecting The door and windows
Exhaust connecting room to the ACH
the room to the
fan is:
corridor is: balcony and outside air is:
Off Closed Closed 0.71
Off Closed Open 14.0
Off Open Open 8.8-18.5
On Closed Closed 12.6
On Closed Open 14.6
On Open Open 29.2

53. Pitfalls in Environmental Control
Setting 2 : Clinic Waiting Area
Vents to clinical
exam rooms
Wall-mounted Commercial “air Exhaust fan and
cleaners” with ultraviolet light ceiling mixing fan
and HEPA filtration

54. Pitfalls in Environmental Control
Do not block windows

55. Pitfalls in Environmental Control
Setting 2 : Clinic Waiting Area
Strengths
Vents and open
doors may allow for
cross-ventilation if
attached rooms are
well ventilated.

56. Pitfalls in Environmental Control
Setting 2 : Clinic Waiting Area
Weaknesses
Crowded waiting area
without screening, or cough
hygiene No reminders of
cough hygiene visible.
Doors closed;
exhaust fan not
Room air cleaners usually properly used
useless – can’t clean enough air

57. Respiratory Protection (RP)
Controls
 Implement RP program
 Isolation rooms
 High-risk areas
 High-risk procedures
 Laboratory testing
 Train HCWs in RP
 N-95 masks
 Fit-testing

58. What are we doing?
 Creating TB fast track started from triage
 Creating semi-negative pressure unit for
handle all TB, HIV and EID cases
 Creating areas for in-patients admission,
while waiting for budget on negative
pressure rooms

59. PRE FILTER
MEDIUM FILTER
RECIRCULATING COIL
HIGH STATIC PLUG FAN
C
C
CDU
OPD
NAGATIVE
EXHAUST FAN PRESSURE SUPPLY AIR
RETURN AIR &
EXHAUST AIR
Ionization

60. Exhaust Air
2.90
6.00
ห้อง treatment
2.90
Exhaust Air
Supply Air
Exhaust Air
2.90
ห้องตรวจ 1
Supply Air
6.00
ห้องตรวจ 2
Supply Air
2.90
Exhaust Air
Supply Air
Exhaust Air
2.90
ห้องตรวจ 3
Supply Air
6.00
2.90
Supply Air