Tuberculosis - Minnesota Dept. of Health

Tuberculosis Quick Guide

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Screening and Diagnosis
Full Provider Guide Chapter: Tuberculosis

Screening and Diagnosis

Initial TB Screening

Bacillus Calmette-Guerin (BCG) vaccine

    • Many refugees have been vaccinated against TB with the BCG vaccine.
    • IGRA or TST testing are not contraindicated in BCG-vaccinated persons, and TST reactions in such persons should be interpreted using the same criteria used for those not BCG-vaccinated. IGRAs are more specific to Mycobacterium tuberculosis and do not detect prior BCG vaccination.
    • The provider should be aware of and explain to the refugee that BCG vaccine primarily is useful in preventing disseminated TB disease in infants and young children but has not been shown to prevent LTBI or pulmonary TB disease.

Chest X-ray

  • Should be done if:
    • the IGRA or TST result is positive (≥ 10 mm induration in most instances),
    • the refugee has a TB Class A or B1 condition identified during their overseas exam,
    • the refugee has TB-related symptoms, or
    • the refugee is infected with HIV.

Culture Confirmation/Clinical Diagnosis

  • The gold standard is culture confirmation, though clinically diagnosed TB disease (i.e., culture-negative or cultures not obtained, with clinical signs and symptoms that improve with treatment) accounts for nearly one-fourth of the TB cases reported in Minnesota.
    • If suspected active TB collect high quality specimens for both acid-fast bacilli (AFB) smear and mycobacterial culture whenever feasible.
    • Be aware that negative AFB cultures do not necessarily rule out active TB disease.

Reporting Cases

  • Refugees with a positive TST or IGRA, no TB-related symptoms, and a negative chest X-ray are candidates for treatment of LTBI, unless they have been previously treated or have medical contraindications. In Minnesota, LTBI is not reportable.
  • In Minnesota, confirmed or suspected cases of TB should be reported to MDH within one working day of identification. Both pulmonary and extrapulmonary forms of TB disease (including culture negative active disease) are reportable. Do not wait for culture confirmation.


  • Drug-resistant TB and extrapulmonary TB
    • Both are more common among foreign-born persons.
    • Common extrapulmonary sites are: lymphatic, pleural, peritoneal and bone/joint.
  • Active TB disease should be carefully ruled out before starting treatment for LTBI.
  • Develop an individualized treatment plan to increase the patient's chances of successful therapy.
    • Plan may include patient education, incentives and enablers, transportation and social service support, referrals to local public health nursing services for treatment monitoring, and coordinating TB treatment with services of other providers.
  • TB medications are available at no cost from MDH. Clinicians may request medications for their patients by going to or calling 651-201-5414.


Foreign-Born TB Cases

  • Consistent with 2009 findings, national TB surveillance in 2010 reported fewer TB cases among foreign-born persons than during 1993-2008. Even with the decline in cases among foreign-born persons, the TB case rate among foreign-born persons in 2010 was 11 times greater than among U.S.-born persons (i).

Latent TB Infection

  • Approximately 5 to 10 percent of LTBI patients will develop active TB disease at some point in their lifetime, without prophylaxis (ii).
  • The risk is higher for children, newly infected persons, and those with certain medical conditions like HIV. Completing therapy for LTBI can reduce the likelihood of developing TB disease by up to 90 percent (iii).

Overseas Screening

  • All refugees are screened overseas for TB prior to arrival, but previously undetected TB cases may appear due to varying quality of the overseas medical examinations and the potential for a lengthy lag period between medical clearance and arrival in Minnesota.

Full Provider Guide Chapter: Tuberculosis


i. Centers for Disease Control and Prevention. Trends in Tuberculosis— United States, 2010. MMWR 2011;60:333-337. Attention: Non-MDH link

ii. Centers for Disease Control and Prevention. Latent Tuberculosis Infection: A Guide for Primary Health Care Providers. Accessed Dec 14, 2009. Attention: Non-MDH link

iii. Centers for Disease Control and Prevention. Targeted tuberculin testing and treatment of latent tuberculosis infection. MMWR. 2000; 49(RR06):1-54. Accessed Dec 14, 2009. Attention: Non-MDH link

Updated Wednesday, November 23, 2011 at 01:04PM