(Page 12 of 40) Module 6: Contact Investigations for Tuberculosis

Module 6
Contact Investigations for Tuberculosis
Page 12 of 40

Medical Record Review (continued)
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The Period of Infectiousness

Determining the period of infectiousness can help focus the contact investigation efforts on those persons who were exposed while the patient was infectious.

The beginning of the infectious period is usually estimated by determining the date of onset of the patient's symptoms (especially coughing).

The period of infectiousness is the time period during which a person with TB disease is capable of transmitting M. tuberculosis. Determining the period of infectiousness can help focus the contact investigation efforts on those persons who were exposed while the patient was infectious. There is no universal, well-established method to determine the period of infectiousness. The beginning of the infectious period is usually estimated by determining the date of onset of the patient's symptoms (especially coughing). Sometimes when it is difficult to obtain a reliable history from the patient about the onset of symptoms, the beginning of the infectious period is estimated to be earlier than the onset of symptoms. Estimating the period of infectiousness should be done by clinical and supervisory staff after a complete assessment of the information available.

The period of infectiousness ends when symptoms have improved, the patient has been receiving adequate treatment for at least 2 to 3 weeks, and the patient has had three consecutive negative sputum smears from sputum collected on different days.

The period of infectiousness ends when all the following criteria are met:

Symptoms have improved
The patient has been receiving adequate treatment for at least 2 to 3 weeks
The patient has had three consecutive negative sputum smears from sputum collected on different days

The medical record review is summarized in Table 6.2 (see Module 5, Infectiousness and Infection Control, for detailed information on infectiousness; see Module 8, Tuberculosis Surveillance and Case Management in Hospitals and Institutions, for more information on medical record reviews).

Table 6.2
Medical Record Review

Information Collected
During the Review Conditions that Increase Likelihood of Infectiousness and Relative Priority of
Contact Investigation

Site of TB disease Pulmonary or laryngeal TB disease

TB symptoms and approximate date symptoms began Coughing, producing a lot of sputum
Hoarseness (may indicate laryngeal TB)

Sputum smear and culture results, including the dates of specimen collection Positive AFB smear results
M. tuberculosis identified in the culture

Chest x-ray results Cavityin the lung

TB treatment, date treatment started, and method of administration No treatment or recently started treatment

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