Self-Study Modules on Tuberculosis
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5: Infectiousness and Infection Control
Answers To Study Questions
5.1. Why does the site of disease affect the infectiousness of a TB
Usually, only people with pulmonary or laryngeal TB (TB of the
larynx) are infectious. This is because these people may be coughing
and expelling tubercle bacilli into the air. People with extrapulmonary
TB only (no pulmonary TB) generally are not infectious.
5.2. List five other factors that affect the infectiousness
of a TB patient.
- Does the chest x-ray show that the patient has a cavity in the
- Is the patient coughing? If so, how often and how forcefully?
- Does the patient cover his or her mouth when coughing?
- Are there acid-fast bacilli on the sputum smear?
- Is the patient receiving adequate treatment?
5.3. When can a TB patient be considered noninfectious?
List all three criteria.
Patients can be considered noninfectious when they meet
all of the following criteria:
- They have been receiving adequate treatment for 2 to 3 weeks
- Their symptoms have improved (for example, coughing less and
no longer have a fever)
- They have THREE consecutive negative sputum smears from sputum
collected on different days
5.4. In what circumstances is TB most likely to be transmitted
in health care facilities?
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.
5.5. What is the main goal of an infection control program?
What three types of controls should this program involve?
The main goal of an infection control program is to detect
TB disease early and to promptly isolate and treat people who have
TB disease. The infection control program should involve three types
- Administrative controls
- Engineering controls
- Personal respiratory protection
5.6. What would make a health care worker suspect that
a patient has TB disease?
Clinicians and other health care workers should suspect
TB disease in any patient who has a persistent cough, bloody sputum,
weight loss or loss of appetite, fever, or night sweats. They should
be especially alert for TB in areas where TB is very common. Also,
health care workers who admit patients to the facility should be
trained to ask appropriate questions to help detect patients who
have signs or symptoms of TB.
5.7. What should be done when a health care worker suspects
that a patient has TB disease?
The patient should be placed in an area away from other
patients (preferably in a TB isolation room) and promptly given
a diagnostic evaluation. The patient should be given a surgical
mask and instructed to keep it on; he or she should also be given
tissues and asked to cover his or her nose and mouth when coughing
or sneezing, even when in an area away from other patients. If the
patient is likely to have TB, he or she should start appropriate
treatment at once.
5.8. What is a TB isolation room? What are the important
characteristics of an isolation room?
TB isolation rooms are rooms in the facility that have
special characteristics to prevent the spread of droplet nuclei
expelled by a TB patient. One characteristic of TB isolation rooms
is that they are at negative pressure relative to other parts of
the facility. Another characteristic is that the air from the isolation
room is exhausted directly to the outdoors or passed through a special
filter that removes all of the droplet nuclei.
5.9. How often should health care workers who may be exposed
to TB be tuberculin skin tested?
Health care workers who may be exposed to TB should be
skin tested upon employment (two-step testing) and at least once
a year thereafter.
5.10. How do ventilation systems help prevent the spread
Ventilation systems are necessary to maintain negative
pressure and to exhaust the air properly. These systems can also
be designed to minimize the spread of TB in other areas of the health
5.11. Give four examples of settings where personal respirators
should be used.
Personal respirators should be used in
- TB isolation rooms
- Rooms where cough-inducing procedures are done
- Ambulances and other vehicles transporting infectious TB patients
- The homes of infectious TB patients
5.12. Where should sputum induction, bronchoscopy, and
other cough-inducing procedures be done?
These medical procedures should be done in special isolation
rooms or booths to prevent any droplet nuclei that are expelled
during the procedure from reaching other parts of the facility.
5.13. How can the health department help health care facilities
in preventing the spread of TB?
The health department can
- Help health care facilities report confirmed or suspected
TB cases as quickly as possible
- Do contact investigations
- Make sure there is a plan for TB patients to receive follow-up
care after they are discharged
- Help the facilities with screening, surveillance, outbreak
investigations, and other aspects of a TB infection control
5.14. What precautions should a health care worker take
when visiting the home of a TB patient who may be infectious?
Health care workers who visit TB patients at home should
take these precautions to protect themselves from the spread of
- Instruct patients to cover their mouth and nose with a tissue
when coughing or sneezing
- Wear a personal respirator when visiting the home of an infectious
TB patient or when transporting an infectious TB patient in
- When it is necessary to collect a sputum specimen in the home,
collect the specimen in a well-ventilated area, away from other
household members; if possible, the specimen should be collected
- Participate in a TB screening and prevention program