Tuberculosis And Airborne

1. Tuberculosis Among Thai
Healthcare Workers:
a Human or System Failure
Anucha Apisarnthanarak, M.D.
Assistant Prof.
Thammasat University Hospital
[email protected]
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
tuberculosisInfection in Health Care
Workers in Resource-Limited Settings
Apisarnthanarak A, et al. Post-exposure detection of TB in Thai HCWs. CID, 2008
No. (%) of patients
Second TST With
M.turberculosi
s infection at 2-
year follow-up
(n = 6)
Initial TST
reaction size
Initial TST
(n = 95)
No change
(n = 87)
Increase of
>10 mm
(n = 8)
> 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)

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

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

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?
Alonso-Echanove, et al. TB among HCWs in Peru. CID, 2002
1994 199719961995
Year
Rate per
100
,
000
HCWs
500
2000
7000
1500
1000
0
709
488
187
60
1163
709
233
187
1418
581
466
334
181
6977
932
792
709
121
Laboratory
Medicine
ED/ICU
All hospital
Other areas

18. Evaluation of potential risk factors for Mycobacterium
tuberculosisinfection among health care workers
(HCWs) from clinical and laboratory areas
Variable
Clinical areas Laboratory areas
n/N PRR
(95% Cl)
P n/N PRR
(95% Cl)
P
Employment in medicine
wards
92/1212.1(1.5-2.9)<.001 _ _ _
Helped in sputum
collection
57/711.5(1.2-1.9)<.001 1/1 _ NS
Contact with person with
active tuberculosis
106/1423.2(1.9-5.3)<.00134/391.9(1.3-2.7)<.001
Duration of
employment≥1 year
102/1561.5(1.0-2.2).0137/521.2(0.8-1.8)NS
Use of common staff
areas
106/1711.1(0.8-1.7)NS 41/462.7(1.6-4.5).001

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

23. Components of TB
Infection Control Plan
Screen clientsto identify persons withsymptoms of TB
disease or on treatment for current TB
Educate onTB in general and on cough hygiene; provide
face masks or tissues to symptomatic (suspect) or known
cases
Expedite TB suspect/casereceipt of services
Investigate on site or refer TB diagnostic servicesand
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 TBdisease in
themselves
Train and educate staff onTB 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. tuberculosisin 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 door29.3-93.2 ACH
Open window(100%) + Closed door15.1-31.4 ACH
Open window(50%) + Closed door10.5-24 ACH
Open window + Open door 8.8 ACH
Y. Li et al. J Hosp Infect. In press.

36. Rapid decay with
windows open:
12 air-changes/hour0
1000
2000
3000
4000
5000
6000
5 10 15 20 25 30 35
Measurement of Natural Ventilation
Escombe AR, et al. PloS Med 2007;4:e68
Windows & doors openedCO
2release
CO
2
concentration
(ppm)
Time (minutes)
Slow CO
2concentration decay
with windows closed: 0.5
air-changes/hour

37. Measurement of Natural Ventilation
Escombe AR, et al. PloS Med 2007;4:e680
2000
4000
6000
8000
10000
Absolute ventolation m
3
/h
Low wind
2 km/h
Wind
>2 km/h
Natural ventilation
Mechanical
ventilation
Windows & doors:
Fully closed
Partially open
Fully open

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
Mixing fans can help
disperse aerosols in
when wind is still
Window area approx
10 m
2
on each side
Excellent
potential for
cross-ventilation
Patient wearing
mask to reduce
aerosol generation

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

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
Single air conditioner per room
Door ajar due to
negative pressure

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

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
Yanai H, Limpakarnnanarat K, Uthaivoravit W, et al. Int J Tuberc Lung Dis 2003;7:36-45.
TB rate: 9.3/100 HCWs (1995-1997) to 2.2/100 HCWs (1998-1999)

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
CASE CONTACT
Site of TB
Cough
Bacillary load
Treatment
Closeness and
duration of contact
Immune status
Previous infection
Ventilation
Filtration
U.V. light
Patient ContactEnvironmental

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

50. Work Practice and
Administrative Controls
Prompt recognition and separationof persons with
infectious TB
Prompt provision of TBand 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
Exhaust
fan is:
The door connecting
the room to the
corridor is:
The door and windows
connecting room to the
balcony and outside air is:
ACH
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
Exhaust fan and
ceiling mixing fan
Vents to clinical
exam rooms
Wall-mounted Commercial “air
cleaners” with ultraviolet light
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.
Room air cleaners usually
useless –can’t clean enough air
Doors closed;
exhaust fan not
properly used

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

60. Supply Air
Supply Air
ห้องตรวจ
1
Supply Air Supply Air
Supply Air
Exhaust Air
Exhaust Air
ห้อง
treatment
ห้องตรวจ
2
6.00 6.006.00
2.90 2.90 2.90 2.90
Supply Air
Exhaust AirExhaust Air
Exhaust Air
ห้องตรวจ
3
2.902.90