Tuberculosis classification system

The current clinical classification system for tuberculosis (TB) is based on the pathogenesis of the disease.

Health care providers should comply with local laws and regulations requiring the reporting of TB. All persons with class 3 or class 5 TB should be reported promptly to the local health department. See list of notifiable diseases.

Classification System for TB

Class	Type	Description
0	No TB exposure Not infected	No history of exposure Negative reaction to tuberculin Tuberculin Tuberculin is the name given to extracts of Mycobacterium tuberculosis, M. bovis, or M. avium that is used in skin testing in animals and humans to identify a tuberculosis infection. Several types of tuberculin have been used for this, of which purified protein derivative is the most important....  skin test
1	TB exposure No evidence of infection	History of exposure Negative reaction to tuberculin skin test
2	TB infection No disease	Positive reaction to tuberculin skin test Negative bacteriologic studies (if done) No clinical, bacteriologic, or radiographic evidence of TB
3	TB, clinically active	M. tuberculosis cultured (if done) Clinical, bacteriologic, or radiographic evidence of current disease
4	TB Not clinically active	History of episode(s) of TB or Abnormal but stable radiographic findings Positive reaction to the tuberculin skin test Negative bacteriologic studies (if done) and No clinical or radiographic evidence of current disease
5	TB suspect	Diagnosis pending TB disease should be ruled in or out within 3 months

CDC TB classification for immigrants and refugees

The U.S. Citizenship and Immigration Services has an additional TB classification for immigrants and refugee

Refugee

A refugee is a person who outside her country of origin or habitual residence because she has suffered persecution on account of race, religion, nationality, political opinion, or because she is a member of a persecuted 'social group'. Such a person may be referred to as an 'asylum seeker' until...

s developed by the Centers for Disease Control and Prevention

Centers for Disease Control and Prevention

The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

(CDC). The B notification program is an important screening strategy to identify new arrivals who have a high risk for TB.

United States Immigrant/Refugee TB Classification - revised 2009

No TB Classification (Normal)

Class A TB with waiver, infectious

Class B1 TB, Pulmonary

Class B1 TB, Extrapulmonary

Class B2 TB Latent TB Infection (LTBI) Evaluation

Class B3 TB, Contact Evaluation