Tuberculosis classification

Main article: Tuberculosis

Tuberculosis classification system

The current clinical classification system for tuberculosis (TB) is based on the pathogenesis of the disease.^[1]

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 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 refugees developed by the Centers for Disease Control and Prevention (CDC).^[2] The B notification program is an important screening strategy to identify new arrivals who have a high risk for TB.^[3]

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

See also

• Tuberculosis radiology for CXR details
• Tuberculosis diagnosis

References

1. Diagnostic Standards and Classification of Tuberculosis in Adults and Children. Am. J. Respir. Crit. Care Med., Volume 161, Number 4, April 2000, 1376-1395. This Official Statement of the American Thoracic Society and the Centers for Disease Control and Prevention was Adopted by the ATS Board of Directors, July 1999. This Statement was endorsed by the Council of the Infectious Disease Society of America, September 1999. Class 0-5 are explained on pages 1391-1392.
2. CDC Immigration Requirements: Technical Instructions for Tuberculosis Screening and Treatment. October 1, 2009. Classifications, see pages 21-22.
3. Revised CDC TB Classification system for overseas screening of immigrants and Refugees with Class B1/B2 TB Conditions. State of Wisconsin, Department of Health Services, Division of Public Health, International Health and Respiratory Disease Unit, Bureau of Communicable Diseases and Emergency Response. September 29, 2009. Accessed 2011-07-27.