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Research Support IPC

Evidence Based

Matsie Mphahlele, MPhil, MSc

MDR-TB Program

Jhpiego-SA

Why is TB Infection Control

Important

� High burden of undiagnosed TB in health care settings and other

congregate settings

� Prevalence of undiagnosed PTB in VCT/ART clinics 8-27%

� (Mohammed et al. Int J Tuberc Lung Dis. 2004; 8(6):792-5, Edwards et al. 16th

Conference on Retroviruses and Opportunistic Infections. Montreal; 2009,

� Prevalence of undiagnosed PTB in mines

� Day et al. IJTLD. 2006;10:523-9, Corbett et al. Am J Respir Crit Care Med

2004;170:673-79)

� High rates of TB infection and disease in HCWs demonstrated in

studies implicating nosocomial transmission

The problem

The problem

Guidelines and recommendations:

International guidelines to reduce TB transmission in resource-limited settings are available

Evidence of the efficacy of TBIC interventions

� It not possible to measure infectiousness of TB or MDR-TB directly, nor can the efficacy of environmental infection control interventions to reduce or prevent transmission be measured directly.

� Lack of evidence on efficacy of most interventions is due to:

� inability to culture Mtb from air under real life conditions

� Molecular amplification methods

� detect nucleic acid from tubercle bacilli in the air, but cannot distinguish living from dead organisms

� nor quantify those with infectious potential.

Evidence of the efficacy of TBIC interventions

� IPC guided by research, studies and evidence-based practices developed to facilitate safe and effective clinical interventions

� Easy to use, reliable, and evidence based strategies appropriate for resource-limited, high TB-HIV prevalence settings are needed

Hierarchy of TB-IC

Prevention of nosocomial

transmission in Russia

• Separation of TB patients according to sputum smear status, drug resistance and treatment regimen •

• Upper Room UVGI fixtures in high and medium risk areas

• Mechanical ventilation designed, installed, commissioned and maintained

• Personal respiratory protection program

• Laboratory biosafety program

Dr. GRIGORY VOLCHENKOV, Vladimir Oblast TB Dispensary

How infectious is MDR-TB, and can it be interrupted?

Results from the field

Purpose of the AIR Facility

To develop an evidence base for

affordable and effective

transmission control

interventions for TB (including

MDR and XDR TB) in

congregate settings within the

context of dual TB and HIV

epidemics.

The AIR Facility

Witbank, Mpumalanga Province, SA

AIR Facility, Experimental Plan

A B

Odd days Even days

Patient room intervention on/off on alternate days

Guinea pig air sampling

UVGI or

other

intervention

Air sampling

from breathing zone

3 2-bed rooms,

corridor and

common room

Infection rate with

patient room

Intervention on

Control infection

rate, patient room

Intervention off

Tuberculosis, 2011. 91(4): p. 329-38.

Reported:

1)High rates of transmission from patients to guinea pigs

2)Transient TB infection

3)Reinfection

4)Limited disease progression

74% guinea pigs infected

� Many guinea pigs reverted their skin test back to 0 mm

0

20

40

60

80

100

TST1 2 3 4 5

0

5

10

15

20

0 4 8 12 18

GP 8

0

5

10

15

20

0 4 8 12 18

GP 33

Timing of TST (weeks)

Timing of TST (weeks)

TST size in mm

TST size in mm

AIR Pilot Study

Effects of natural ventilation in health care settings

� Used CO2 clearance� Naturally ventilated rooms – 28 ACH� Pre-1950’s – 40 ACH

� Mechanically ventilated negativepressure rooms - 12 ACH

� Calculated risk of TB transmissiono 39% in mechanically ventilated –vepr roomso 33% in naturally ventilated modernroomso 11% in naturally ventilated pre-1950’s rooms

Escombe AR et al; PLoS Medicine 2007

Two predominant types of traditional home construction in Tugela Ferry. A. Round-shaped

home with thatched roof B. Box-shaped home with metal roof.

Lygizos et al. BMC Infectious Diseases 2013 13:300 doi:10.1186/1471-2334-13-300

Natural ventilation reduces high TB transmission risk in traditional homes in rural KwaZulu-Natal, South Africa

Natural ventilation reduces high TB transmission risk in

traditional homes in rural KwaZulu-Natal, South Africa

Table 1

ACH and estimated TB risk in predominant home types

All homes Box-shaped, Metal-roofed

Round-shaped, Thatch-

roofed

ACH Mean (SD) Mean (SD) Mean (SD)p-value

 Closed 3 (2.9) 3 (2.7) 3 (3.3)0.50

 Windows Open 9 (7.1) 13 (8.1) 5 (2.9)0.01

 Windows & Door

20 (13.1) 27 (9.7) 13 (12.8)0.01 Open

*TB Risk (10h exposure)

 Closed 55.4 (27.8) 58.3 (24.7) 52.5 (31.5)0.62

 Windows Open 21.5 (14.1) 24.7 (18.1) 18 (8.4)0.32

 Windows & Door

9.6 (4.7) 8.9 (3.6) 10 (5.6)0.44 Open

Wells Riley equation: C = S(1 − e− Iqpt/Q) where C = number of new cases, S = number of susceptible individuals, I = number of infectors (presumed to be 1 per household), q = number of infectious quanta produced per hour per infector (assumed to be 13 based on previous studies) [22], p = pulmonary ventilation rate of susceptible individuals (0.6 m3/h, previously established), t = exposure time of susceptible individuals, Q = absolute room ventilation (ACH*room volume). The probability of a new case was C/S.Lygizos et al.

Lygizos et al. BMC Infectious Diseases 2013 13:300 doi:10.1186/1471-2334-13-300

Wind-driven turbine roof ventilators

Wind-Driven Roof Turbines: A Novel Way to Improve Ventilation for TB Infection Control in Health Facilities. HCox, R Escombe et al. PLoS One 2012

UPPER ROOM-ULTRAVIOLET GERMICIDAL IRRADIATION

(UVGI)

UVGI

WHO recommendations:

� Priority should be given to achieving adequate air changes per hour using ventilation systems

� If not possible, UVGI is a complementary intervention

- Escombe AR et al. Plos Med 2009 (March) ; 6

Lima Peru- Escombe et al

73% efficacy

EXPERIMENTAL DESIGN:

ODD DAYS:

EVEN DAYS:

ANIMAL ROOM 1

ANIMAL ROOM 2

254 nm Irradiance: 250µµµµW/ cm2

Ventilation ducts in patient rooms Paddle Fans Assure Good Air Mixing

Results

UV1 Intervention Control

TST-1 0 1TST-2 0 3TST-3 0 5TST-4 0 0TOTAL 0 9

UV2

TST-1 3 17TST-2 12 30TST-3 0 1TOTAL* 15 48

*p<0.0005

Combined hazard ratio 4.9 (CI.95: 2.8, 8.6)

Efficacy:80%

Hazard

of becom

ing infe

cte

d

EFFECT OF ACH AND

MIXING FAN ON UV

EFFECTIVENESS

AIR MIXING

Personal Respiratory Protection

Special filters in place to prevent inhalation ofdroplet nuclei

• N95 (or greater) or FFP2 (or greater)• Evidence based on:Mathematical modelingLaboratory testing using surrogate particlesExpert opinion

Personal Respiratory Protection

EXPERIMENTAL DESIGN:

ODD DAYS:

EVEN DAYS:

ANIMAL ROOM 1

ANIMAL ROOM 2

Results

2.3-fold (95% CI, 1.5–3.4; P , 0.0005) lower risk among guinea pigs exposed to air exhausted from the ward whenpatients wore face masks.

*56% (95% CI, 33–71%) risk reduction in transmission

While the evidence-base has grown, there are several challenges...

� Lack of expertise and experience in ventilation design, construction, commissioning and maintenance

� Practical implementation and application

� Long term hospitalization with poor isolation tradition; neglect of administrative infection control principles is quite common

� Investments for TB control often lack prioritization

� Sustainability of IC interventions

� Critical gaps related to knowledge and skills in TB IC among HCW

� Enforcement of community supported treatment and management of patients

Summary

� Health care workers are at risk for contracting TB and need much higher levels of protection than they currently receive.

� Experiments have demonstrated that MDR TB transmission can be interrupted through implementation of existing transmission control strategies and technology.

� Experiments have demonstrated that standardized treatment of patients for MDR-TB rapidly suppresses MDR-TB transmission.

THANK YOU