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Self-Study Modules for Effective TB Interviewing
The TB interview
Infectious Period
In order to bring focus to the interview process, the infectious
period must be determined. This period is a time frame in which
potential exposure to others may have occurred while the patient
was infectious or able to transmit TB. Often, the beginning of
the infectious period is when the onset of symptoms occurs, especially
coughing. Local or state standards should be used to determine
the beginning of the infectious period. Some health department
guidelines denote a specified period prior to the patient recollection
of the onset of symptoms, particularly coughing.
For the purpose of the contact investigation, the end of the infectious
period is determined by the existence of all of the following
criteria
- Symptoms, such as frequency and intensity of cough, have improved
- Patient has been receiving adequate treatment for at least 2
weeks
- Patient has shown some evidence of a bacteriological response,
such as the reduction of the grade of the AFB sputum smear or
negative sputum smears
or
- Exposure to contacts has ended
The infectious period should be stated in the form of start date
to end date. The infectious period provides a timeframe for the
patient when identifying information on contacts.
The determination of the infectious period is based on several
factors and should result from a collection of all relevant information
from both the patient and the patient’s medical record. The infectious
period may exceed 6 months; however, the patient’s memory of details
beyond that time frame may be unreliable. Regardless, if review
of the patient’s medical record or other source indicates that the
patient has had signs and symptoms of pulmonary or laryngeal TB
for more than 6 months, collection of contact and congregate setting
information prior to that time should be done. Using a retrospective
timeline, the results of contact evaluations will help determine
when to stop identifying more contacts. This timeline should start
with the date of the interview and work its way back in time.
A patient will most likely not be able to provide you with exact
onset dates for symptoms. Asking the patient to associate symptoms
with events may assist. For example, a patient can be asked if
he or she remembers coughing around a major event or holiday (e.g.,
his or her birthday, Christmas).
In a source case investigation for a child, the infectious period
generally begins 3 months prior to the date of the interview. The
infectious period end date is the interview date. The factors regarding
treatment and sputum conversion for ending the infectious period
in source case investigations do not apply because most young children,
as well as persons with latent TB infection, are not usually infectious.
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