Unit 3. Infection control (IC)
basics and the WHO
set of measures for TB IC
TB Infection Control Training for
Managers
at National and Subnational Level
Objectives
After this unit, the participant will
• understand the mechanisms of TB
transmission
• be able to describe the factors affecting
the risk of TB transmission (patient,
recipient, bacterial and institutional
factors)
• be able to list the WHO set of measures
for TB infection control
2
Standard precautions
•
Use with every patient, at every health
care visit
Main elements include:
•
–
–
–
–
–
Hand hygiene
Respiratory hygiene, cough etiquette
Use of personal protective equipment to
avoid direct contact with patient’s blood, body
fluids, secretions, and non intact skin
Prevention of needle stick/sharp injury
Cleaning and disinfection of the environment
and equipment
3
Additional precautions
Added to standard precautions
depending on transmission mode of the
patient’s suspected pathogen:
• Airborne (measles, chickenpox)
• Droplet (SARS, avian influenza)
• Contact (staphylococcus aureus)
4
Airborne vs. droplet transmission
Airborne
• Small droplet nuclei <5 microns diameter
• Stay suspended in air
• When inhaled, can reach the alveoli and cause
infection
Droplet
• Large droplets > 5 microns in diameter.
• Do not remain suspended in the air, so no
special air handling or ventilation is required
• If inhaled, do not reach alveoli
5
Fate of
droplet nuclei vs. droplets
Droplet nuclei (airborne transmission)
• A 1.0 μm droplet nucleus will settle at a
rate of 0.0035 cm/sec (or 3 m in 24 hours)
Large droplets (droplet transmission)
• Fall to ground or other horizontal surface
relatively fast
6
A sneeze
7
Number and size of organisms
Number of organisms released
Talking
0-200
Coughing 0-3,500
Sneezing 4,500- 1,000,000
Size of the droplets (function of air velocity)
Sneeze ~3-10 m/s
75% are ~10 μm in diameter
< 25% are droplet nuclei (1-5 μm in
diameter).
Wells 1955, Duguid 1945, Wells/Riley 1961, et al.
8
Airborne precautions
• Place patient in airborne precaution
room which has:
– 12 or more air changes per hour
– Control of airflow direction
• Limit the movement of the patient
– Ensure patients wear a surgical mask if
outside their rooms
• Use a particulate respirator whenever
entering and providing care
9
What is the risk for TB
transmission?
10
Who can infect whom?
Patient to
Worker to
Visitor to
Patient
Worker
Visitor
11
Factors affecting the risk of
transmission
•
•
•
•
Patient
Recipient
Bacterial
Institutional
12
Patient factors
• Infectiousness: sputum smear, cavitation, force
and frequency of cough*
• Cough-inducing procedures
• Treatment (time since start of correct treatment
and adherence)*
• Understanding of TB, cough etiquette*, and
adherence to IC practices
• General health status (immune status,*
nutrition, co-morbidities, e.g. diabetes)
*Influence the number of infectious bacilli
released
13
When is TB most infectious
• When it occurs in the lungs or larynx
• Until the person has
– Completed at least 2 weeks of
appropriate therapy, preferably with
direct observation
– Has become smear negative
– Has improvement in symptoms
14
Recipient factors
• Closeness, duration and frequency of contact*
• Risk of TB infection (prior treatment, age,
homelessness, contact of known case, etc.)
• Adherence to IC practices*
• Susceptibility either intrinsic or acquired (i.e.
immune status, general health, other diseases,
nutrition, age)
*Influence dose of inhaled bacilli
15
Recipient factors
16
Bacterial factors
• Intrinsic virulence of MDR-TB bacilli may
not be greater than drug susceptible bacilli
• However, patients with MDR-TB may
infect more people due to their prolonged
period of infectiousness
• Previously treated cases (treatment
failure, default, relapse) have increased
levels of MDR-TB
17
Institutional factors (1)
• Exposure in small, enclosed spaces
• Lack of adequate ventilation
• Re-circulation of contaminated air
18
Institutional factors (2)
• Fixed characteristics (type, location, structure)
• Variable characteristics (temperature, humidity,
rain)
• Type and number of people served by institution
(crowding)
• Resources available
• Policies and practices governing patient
movement and housing
• Time lag between detection of disease or drug
resistance (reporting and proper treatment)
19
Institutional factors
20
Institutional factors (3):
path of the patient
•
•
•
•
•
•
In-patients versus out-patients
Diagnosed TB cases vs. undetected
Intake, triage, registration
Waiting area
Laboratory, radiology, pharmacy
High risk procedures
21
Areas visited by TB patients
Reception
General wards
Home/referral clinics
OPD
TB Department
VCT
Maternity ward
Unsuspected
TB patients
Radiology
TB wards
Laboratory
Pharmacy
Other departs
22
Institutional factors (4)
path of the specimen
•
•
•
•
•
•
•
•
Collection location and procedures
Registration and identification number
Storage
Transportation
Lab log entry
Processing procedures
Smear, culture, drug susceptibility testing
Disposal procedures
23
Reorganization for optimal
services (functionality)
•
•
•
•
Maximise infection control
Minimize risk of TB transmission
Maximise quality of patient services
Minimize cost (capital and recurring)
24
Set of measures for TB infection
control, WHO, 2009
1. National and subnational levels
•
Managerial activities
2. Facility level
•
•
•
•
Managerial activities
Administrative controls
Environmental controls
Personal protection
25
What are managerial activities?
Activities used by programme managers
to support and facilitate the
• implementation
• operation
• maintenance
• evaluation
of TB infection control at the national, subnational and facility levels
26
Managerial activities
—national level (1)
• Identify and strengthen a coordinating body
• Develop a comprehensive plan for IC to
include
– Budget
– Human resource requirements
• Ensure that health facility design,
construction, renovation and use are
appropriate
27
Managerial activities
—national level (2)
• Conduct surveillance of TB disease
among health care workers
• Assess TB transmission risk at all levels of
the health system and congregate settings
• Address advocacy communication and
social mobilization (ACSM),
engagement of civil society
• Monitor and evaluate TB IC measures
• Enable and conduct operational research
28
Set of measures--facility level
•
•
•
•
Managerial activities
Administrative controls
Environmental controls
Personal protective equipment
29
Managerial activities at the
facility level
•
•
•
•
•
•
Identify and strengthen coordinating body,
develop facility plan
Rethink use of available spaces
Assess facility, conduct surveillance of TB
disease among health workers
Address ACSM for health workers, patients
and visitors
Monitor and evaluate set of TB IC measures
Participate in research efforts
30
Administrative controls—
facility level
• Promptly identify people with TB symptoms
(triage),
• Separate them
• Cough etiquette
• Minimize time in health care settings.
• Provide a package of prevention and care for
health workers, including HIV prevention
–For HIV-positive health workers,
antiretroviral therapy and isoniazid preventive
therapy
31
Environmental controls—
facility level
Reduce the concentration of infectious
particles in the air via:
• Ventilation
– Natural, mechanical, or mixed mode
– Can direct the flow of infectious air away
from health care workers and other patients
• Ultraviolet germicidal irradiation (UVGI)
32
Personal protective equipment
Use particulate respirators
• Along with administrative and
environmental controls
• In situations where there is an increased
risk of TB transmission
• With comprehensive training program
• With fit testing
33
Controls work at different points
of the chain of transmission
Patient coughs droplet nuclei into air
(administrative controls)
Droplet nuclei are suspended in the air
(environmental controls)
Exposed person breathes in M. tuberculosis
(particulate respirators)
34
Priority measures for IC
Control
Why?
1
Administrative
Prevent the generation of droplet
nuclei. First line defence.
2
Environmental
2nd line defence, since cannot
eliminate all TB exposure.
3
Particulate
respirators
Use only with the other 2 controls,
in situations with a high risk of TB
transmission. Protect only the
health care worker, not other
patients or visitors
Managerial IC activities are required for all facilities 35
Summary
• TB is spread through droplet nuclei that
stay airborne for prolonged periods, and
can be inhaled
• Patient, recipient, bacterial and
institutional factors influence the risk of
TB transmission
• WHO recommends a set of TB infection
control measures including managerial,
administrative, environmental, and
personal protective equipment
36