Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]
Overview
Classification
Below is a table with the current classification system of tuberculosis (TB), based on its pathogenesis:[1]
|
Class
|
Type of Tuberculosis
|
Description
|
0
|
- No TB exposure
- Not infected
|
- No history of TB exposure
- Negative result to a TST or IGRA
|
1
|
|
- History of TB exposure
- Negative result to a TST (given at least 8-10 weeks after exposure) or IGRA
|
2
|
- TB infection
- No TB disease
|
- Positive result to a TST or IGRA
- Negative smears and cultures (if done)
- No clinical or x-ray evidence of active TB disease
|
3
|
|
|
4
|
- Previous TB disease (not clinically active)
|
- Medical history of TB disease
- Abnormal but stable x-ray findings
- Positive result to a TST or IGRA
- Negative smears and cultures (if done)
- No clinical or x-ray evidence of active TB disease
|
5
|
|
|
CDC TB Classification for Immigrants and Refugees
|
Class
|
Description
|
No TB Classification
|
Applicants with normal tuberculosis screening examinations
|
Class A TB with waiver
|
All applicants who have tuberculosis disease and have been granted a waiver
|
Class B1 TB, Pulmonary
|
No treatment:
- Have negative acid-fast bacilli sputum smears
- Have negative cultures
- Are not diagnosed with tuberculosis
- Can wait to have tuberculosis treatment started after immigration
Completed treatment:
- Applicants who were diagnosed with pulmonary tuberculosis and successfully completed directly observed therapy prior to immigration
- The cover sheet should indicate if the initial sputum smears and cultures were positive and if drug susceptibility testing results are available
|
Class B1 TB, Extrapulmonary
|
Applicants with evidence of extrapulmonary tuberculosis
The anatomic site of infection should be documented
|
Class B2 TB, LTBI Evaluation
|
Applicants who have a tuberculin skin test ≥10 mm or positive IGRA but otherwise have a negative evaluation for tuberculosis
The size of the TST reaction or IGRA result, the applicant’s status with respect to latent TB infection treatment, and the medication(s) used should be documented
For applicants who had more than one TST or IGRA, all dates and results and whether the applicant’s TST or IGRA converted should be documented
Contacts with TST ≥5 mm or positive IGRA should receive this classification (if they are not already Class B1 TB, Pulmonary)
|
Class B3 TB, Contact Evaluation
|
Applicants who are a recent contact of a known tuberculosis case
The size of the applicant’s TST reaction or IGRA response should be documented
Information about the source case, name, alien number, relationship to contact, and type of tuberculosis should also be documented.
|
References
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