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    TB and Hansen's Disease Branch

    MC 1939
    P.O. Box 149347
    Austin, TX 78756-9347

    Fax: 512-533-3167

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Epi Profile Section 5 - Recent Transmission

The Centers for Disease Control and Prevention (CDC) estimated 18% of TB cases in Texas were attributed to recent transmission, compared to 13% of cases nationally.[1] The CDC defines a TB case as a recent transmission if a likely source case can be identified in a person who:

  • has the same Mycobacterium tuberculosis genotype;
  • has an infectious form of TB disease;
  • resides within ten miles of the index TB case;
  • is ten years of age or older; and
  • was diagnosed within two years before the index TB case

Of the 18% of the recent transmission cases, 8% were defined as extensive recent transmission.  Extensive recent transmission is defined as when a TB case meets the criteria above for recent transmission, and the case belongs to a likely transmission chain of six or more cases.[2]

The infectiousness of a patient can contribute to recent transmission. A positive AFB sputum smear indicates the patient is considered infectious and chest x-ray results with cavitation indicate advanced TB disease.

In 2017, 37.7% of cases had a positive AFB smear and non-cavitary chest x-ray, and 23.1% of cases had a cavitary chest x-ray regardless of AFB smear result, of those 15.8% had a cavitary chest x-ray and a positive AFB smear.


[1] Centers for Disease Control and Prevention (CDC). Report of Verified Case of Tuberculosis Instruction Manual, 2009.  Atlanta, GA: US Department of Health and Human Services, CDC; 2019.

[2] Centers for Disease Control and Prevention (CDC). Reported Tuberculosis in the United States, 2017. Atlanta, GA: US Department of Health and Human Services, CDC; 2019.


Table of Contents | An Overview of Tuberculosis in Texas | Distribution of Tuberculosis in Texas | Affected Populations | Case Diagnosis | Recent Transmission | Mortality | Risk Factors Associated with Tuberculosis | Drug Resistant TB | Targeted Testing | Reporting Requirements | References

Last updated June 24, 2019