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{{Tuberculosis}}
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{{CMG}}; {{AE}} {{Mashal Awais}}; {{JS}}


==Overview==
==Overview==
Tuberculosis can be classified into 6 main categories according to exposure, symptoms, and diagnostic testing. The classification ranges from Class 0, in people with no previous exposure to TB and negative tuberculin skin testing and/or interferon-gamma release assay (2 methods of screening for TB), to Class 3 for active TB infection and Class 5 for suspected TB infection based on signs and symptoms of the disease. The U.S. Citizenship and Immigration Services has also designed a special classification for immigrants and refugees according to the risk of infection.


==Classification==
==Classification==
Below is a table with the current classification system of [[tuberculosis]] ([[TB]]), based on its [[pathogenesis]]:<ref name=CDC>{{cite web | title = TB Classification | url = http://www.cdc.gov/tb/publications/slidesets/selfstudymodules/module1/classification.htm }}</ref>  
Below is a table of the current classification system of [[tuberculosis]] ([[TB]]), according to its [[pathogenesis]]:<ref name="CDC">{{cite web | title = TB Classification | url = http://www.cdc.gov/tb/publications/slidesets/selfstudymodules/module1/classification.htm }}</ref>  
{| style="border: 0px; font-size: 90%; margin: 3px;" align=center
{| style="border: 0px; font-size: 90%; margin: 3px;" align="center"
|valign=top|
| valign="top" |
|+
|+
! style="background: #4479BA; width: 50px;" | {{fontcolor|#FFF|Class}}
! style="background: #4479BA; width: 50px;" |{{fontcolor|#FFF|Class}}
! style="background: #4479BA; width: 250px;" | {{fontcolor|#FFF|Type of Tuberculosis}}
! style="background: #4479BA; width: 250px;" |{{fontcolor|#FFF|Type of Tuberculosis}}
! style="background: #4479BA; width: 250px;" | {{fontcolor|#FFF|Description}}
! style="background: #4479BA; width: 250px;" |{{fontcolor|#FFF|Description}}
|-
|-
| style="padding: 5px 5px; background: #DCDCDC; font-weight: bold" |
| style="padding: 5px 5px; background: #DCDCDC; font-weight: bold" |
0
0
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*No [[TB]] exposure
No [[TB]] exposure<br>
*Not infected
Not infected
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*No history of [[TB]] exposure
No history of [[TB]] exposure<br>
*Negative result to a [[TST]] or [[IGRA]]
A negative [[TST]] or [[IGRA]]
|-
|-
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
1
1
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*[[TB]] exposure
[[TB]] exposure<br>
*No evidence of [[infection]]
No evidence of [[infection]]
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*History of [[TB]] exposure
History of [[TB]] exposure<br>
*Negative result to a [[TST]] (given at least 8-10 weeks after exposure) or [[IGRA]]
A negative [[TST]] (given at least 8-10 weeks after exposure) or [[IGRA]]
|-
|-
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
2
2
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*[[TB]] infection
[[TB]] infection<br>
*No [[TB]] disease     
No [[TB]] disease     
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*Positive result to a [[TST]] or [[IGRA]]
Positive [[TST]] or [[IGRA]]<br>
*Negative smears and cultures (if done)
Negative smears and cultures (if done)<br>
*No clinical or [[x-ray]] evidence of active [[TB]] disease
Absent clinical picture of active [[TB]] disease
or abnormal [[x-ray]] findings
|-
|-
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
3
3
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*Clinically active [[TB]]
Clinically active [[TB]]
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*Positive culture (if done) for ''[[M. tuberculosis]]''
Positive culture (if done) for ''[[M. tuberculosis]]''<br>
*Positive result to a [[TST]] or [[IGRA]], and clinical, bacteriological, or [[x-ray]] evidence of [[TB]] disease  
Positive [[TST]] or [[IGRA]], and clinical, bacteriological, or [[x-ray]] evidence of [[TB]] disease  
|-
|-
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
4
4
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*Previous [[TB]] disease (not clinically active)
Previous [[TB]] disease (not clinically active)
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*Medical history of [[TB]] disease
Medical history of [[TB]] disease<br>
*Abnormal but stable [[x-ray]] findings
Abnormal but stable [[x-ray]] findings<br>
*Positive result to a [[TST]] or [[IGRA]]
Positive [[TST]] or [[IGRA]]<br>
*Negative smears and cultures (if done)
Negative smears and cultures (if done)<br>
*No clinical or [[x-ray]] evidence of active [[TB]] disease
Absent clinical picture of active [[TB]] disease
or abnormal [[x-ray]] findings
|-
|-
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
| style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
5
5
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*Suspected [[TB]]
Suspected [[TB]]
| style="padding: 5px 5px; background: #F5F5F5;" |
| style="padding: 5px 5px; background: #F5F5F5;" |
*[[Signs]] and [[symptoms]] of [[TB]] disease, but evaluation not complete
Clinical manifestations of [[TB]] disease, but incomplete evaluation.
The diagnosis s pending.
The patient should not be in this class for more than three months.
|-
|-
|}
|}


==CDC TB Classification for Immigrants and Refugees==
==CDC TB Classification for Immigrants and Refugees==
The [[U.S. Citizenship and Immigration Services]] has an additional TB classification for [[immigrant]]s and [[refugee]]s developed by the [[Centers for Disease Control and Prevention]] (CDC).  The 'B Notification Program' is an important screening strategy to identify new arrivals who have a high risk for TB.
Based on the U.S. Citizenship and Immigration Services, developed by the [[Centers for Disease Control and Prevention]] ([[CDC]]), tuberculosis for immigrants and refugees s classified into the following categories: <ref name="CDC2">{{cite web | title = TB Classification US Citizenship and Immigration Services | url = http://www.cdc.gov/immigrantrefugeehealth/pdf/tuberculosis-ti-2009.pdf }}</ref>
{| border="1" cellpadding="5"
{| class="wikitable" style="border: 0px; font-size: 90%; margin: 3px;" align="center"
|+ United States Immigrant/Refugee TB Classification
| valign="top" |
 
|+
|- align="center"|
! style="background: #4479BA; width: 100px;" |{{fontcolor|#FFF|Class}}
|Class || Chest X-ray || AFB smear || Restrictions
! style="background: #4479BA; width: 500px;" |{{fontcolor|#FFF|Description}}
 
!Travel Clearance
|-
|-
| A - TB, infectious|| Active TB || Positive || No entry to U.S. until treated and smears are negative
! style="padding: 5px 5px; background: #DCDCDC; font-weight: bold" |
 
No [[TB]] Classification   
| style="padding: 5px 5px; background: #F5F5F5;" |
Applicants with normal tuberculosis [[screening]] examinations. No discernible HIV infection and normal CXR.  
|Valid for 6 months from evaluation
|-
|-
| B1 - TB, clinically active, not infectious || Active TB || Negative || Report to local health department for further medical evaluation within 30 days of arrival in U.S.
! style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
 
Class A [[TB]]
| style="padding: 5px 5px; background: #F5F5F5;" |
All applicants who have tuberculosis disease including applicants with extrapulmonary TB. In addition, CXR indicates pulmonary TB disease, regardless of sputum smear and culture results.
|Not cleared for travel until treatment is completed. Exceptions are available for granted waivers.
|-
|-
| B2 - TB, not clinically active|| Inactive TB || Not required unless symptomatic || Same as above
! style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |Class B0 TB, Pulmonary
 
|Applicants who were previously diagnosed with TB or came to the physician during the TB treatment course. Additionally, successful completion of the Division of Global Migration and Quarantine (DGMQ) prior to immigration is required.
|It can be valid for 3 months from the last negative culture results.
|-
|-
| No class (Normal) || Normal || Not required || None
! style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
Class B1 [[TB]], [[Pulmonary]]
| style="padding: 5px 5px; background: #F5F5F5;" |
'''No treatment:'''


|}
*Applicants with a medical history, [[physical exam]], or [[CXR]] findings that indicate [[pulmonary]] tuberculosis but:


:*Have negative [[acid-fast]] [[bacilli]] sputum smears
:*Have negative cultures
:*Are not diagnosed with tuberculosis
:*They can initiate tuberculosis treatment  after immigration


'''Completed treatment:'''


*Applicants who had a previous diagnosis of pulmonary tuberculosis and successfully completed directly observed therapy prior to immigration
*The cover sheet must include whether the initial sputum smears and cultures were positive and if drug susceptibility testing results are available
|It can be valid for 3 months from the last negative culture results.
|-
! style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
Class B1 TB, Extrapulmonary   
| style="padding: 5px 5px; background: #F5F5F5;" |
Applicants with evidence of [[extrapulmonary tuberculosis]], with normal CXR and negative sputum smears and cultures.<br>
The anatomic site of [[infection]] should be documented
|It can be Valid for 3 months from the last negative culture results.
|-
! style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
Class B2 TB, LTBI Evaluation   
| style="padding: 5px 5px; background: #F5F5F5;" |
Applicants who have a [[TST]] ≥10 mm or positive [[IGRA]] but otherwise tuberculosis evaluation is negative <br>
The [[TST]] reaction size or [[IGRA]] result, the applicant’s status regarding latent TB infection (LTBI) treatment, and the medication(s) used must be included<br>
Applicants with more than one [[TST]] or [[IGRA]], all results and dates must be ncluded<br>
Contacts with [[TST]] ≥5 mm or positive [[IGRA]] should be classified according to this classification (if they are not already Class B1 TB, Pulmonary)
|Valid for 6 months from completion of evaluation.
|-
! style="padding: 5px 5px; background: #DCDCDC;font-weight: bold" |
Class B3 TB, Contact Evaluation   
| style="padding: 5px 5px; background: #F5F5F5;" |
Applicants who have been in contact of a known tuberculosis case<br>
The size of the applicant’s [[TST]] reaction or [[IGRA]] result must be included<br>
The name, source case, alien number, relationship to contact, and type of tuberculosis must be included.
|Valid for 6 months from completion of the evaluation.
|-
|}<br />
{| class="wikitable"
|+
!Risk Classification
!Necessity of testing
!Frequency of testing
!
|-
|Low Risk
|Settings where Tb infected individuals are unlikely to be present
|Not required unless there has been exposure to TB
|
|-
|Medium Risk
|Settings where health care workers (HCWs) are likely to encounter individuals with TB
|Testing should be repeated every year
|
|-
|Potential Ongoing Transmission
|Settings wehere person to person transmission of TB was documented in the past year
|Testing should be repeated every 8 weeks until making sure that there has been no ongoing transmission.
|
|}
<br />
==References==
==References==
{{reflist|2}}
{{reflist|2}}
{{WH}}
{{WS}}


[[Category:Disease]]
[[Category:Disease]]
[[Category:Infectious disease]]
[[Category:Pulmonology]]
[[Category:Pulmonology]]
[[Category:Bacterial diseases]]
[[Category:Bacterial diseases]]
[[Category:Primary care]]
{{WH}}
{{WS}}

Latest revision as of 15:56, 3 March 2021

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mashal Awais, M.D.[2]; João André Alves Silva, M.D. [3]

Overview

Tuberculosis can be classified into 6 main categories according to exposure, symptoms, and diagnostic testing. The classification ranges from Class 0, in people with no previous exposure to TB and negative tuberculin skin testing and/or interferon-gamma release assay (2 methods of screening for TB), to Class 3 for active TB infection and Class 5 for suspected TB infection based on signs and symptoms of the disease. The U.S. Citizenship and Immigration Services has also designed a special classification for immigrants and refugees according to the risk of infection.

Classification

Below is a table of the current classification system of tuberculosis (TB), according to its pathogenesis:[1]

Class Type of Tuberculosis Description

0

No TB exposure
Not infected

No history of TB exposure
A negative TST or IGRA

1

TB exposure
No evidence of infection

History of TB exposure
A negative TST (given at least 8-10 weeks after exposure) or IGRA

2

TB infection
No TB disease

Positive TST or IGRA
Negative smears and cultures (if done)
Absent clinical picture of active TB disease or abnormal x-ray findings

3

Clinically active TB

Positive culture (if done) for M. tuberculosis
Positive TST or IGRA, and clinical, bacteriological, or x-ray evidence of TB disease

4

Previous TB disease (not clinically active)

Medical history of TB disease
Abnormal but stable x-ray findings
Positive TST or IGRA
Negative smears and cultures (if done)
Absent clinical picture of active TB disease or abnormal x-ray findings

5

Suspected TB

Clinical manifestations of TB disease, but incomplete evaluation. The diagnosis s pending. The patient should not be in this class for more than three months.

CDC TB Classification for Immigrants and Refugees

Based on the U.S. Citizenship and Immigration Services, developed by the Centers for Disease Control and Prevention (CDC), tuberculosis for immigrants and refugees s classified into the following categories: [2]

Class Description Travel Clearance

No TB Classification

Applicants with normal tuberculosis screening examinations. No discernible HIV infection and normal CXR.

Valid for 6 months from evaluation

Class A TB

All applicants who have tuberculosis disease including applicants with extrapulmonary TB. In addition, CXR indicates pulmonary TB disease, regardless of sputum smear and culture results.

Not cleared for travel until treatment is completed. Exceptions are available for granted waivers.
Class B0 TB, Pulmonary Applicants who were previously diagnosed with TB or came to the physician during the TB treatment course. Additionally, successful completion of the Division of Global Migration and Quarantine (DGMQ) prior to immigration is required. It can be valid for 3 months from the last negative culture results.

Class B1 TB, Pulmonary

No treatment:

  • Have negative acid-fast bacilli sputum smears
  • Have negative cultures
  • Are not diagnosed with tuberculosis
  • They can initiate tuberculosis treatment after immigration

Completed treatment:

  • Applicants who had a previous diagnosis of pulmonary tuberculosis and successfully completed directly observed therapy prior to immigration
  • The cover sheet must include whether the initial sputum smears and cultures were positive and if drug susceptibility testing results are available
It can be valid for 3 months from the last negative culture results.

Class B1 TB, Extrapulmonary

Applicants with evidence of extrapulmonary tuberculosis, with normal CXR and negative sputum smears and cultures.
The anatomic site of infection should be documented

It can be Valid for 3 months from the last negative culture results.

Class B2 TB, LTBI Evaluation

Applicants who have a TST ≥10 mm or positive IGRA but otherwise tuberculosis evaluation is negative
The TST reaction size or IGRA result, the applicant’s status regarding latent TB infection (LTBI) treatment, and the medication(s) used must be included
Applicants with more than one TST or IGRA, all results and dates must be ncluded
Contacts with TST ≥5 mm or positive IGRA should be classified according to this classification (if they are not already Class B1 TB, Pulmonary)

Valid for 6 months from completion of evaluation.

Class B3 TB, Contact Evaluation

Applicants who have been in contact of a known tuberculosis case
The size of the applicant’s TST reaction or IGRA result must be included
The name, source case, alien number, relationship to contact, and type of tuberculosis must be included.

Valid for 6 months from completion of the evaluation.


Risk Classification Necessity of testing Frequency of testing
Low Risk Settings where Tb infected individuals are unlikely to be present Not required unless there has been exposure to TB
Medium Risk Settings where health care workers (HCWs) are likely to encounter individuals with TB Testing should be repeated every year
Potential Ongoing Transmission Settings wehere person to person transmission of TB was documented in the past year Testing should be repeated every 8 weeks until making sure that there has been no ongoing transmission.


References

  1. "TB Classification".
  2. "TB Classification US Citizenship and Immigration Services" (PDF).

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