Corrections_Today_January_February_2019

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These tools and tests should include an interferon gamma release assay (IGRA) blood test , which the Centers for Disease Control (CDC) now recommends for most of the U.S. testing population. 7 Unlike the traditionally-used tuberculin skin test (TST), IGRA tests can be completed in one visit, making them better suited for intake and contact screening by eliminating incomplete TST testing of inmates with shorter sentences or who are transferred between facilities. 8 IGRA tests are also more cost-effective in corrections facilities: a 2016 study found that the cost per LTBI case detected was three times higher for the TST than for a specific IGRA blood test. 9 Additionally, TB blood tests do not cross-react with Bacillus Calmette–Guérin (BCG) TB vaccine, resulting in fewer false-positives and quicker identification of individuals with true LTBI.

STUDIES HAVE SHOWN that using a blood test in correctional settings may improve identification of LTBI-positive individuals at high risk for TB. 5

BENEFITS OF TB BLOOD TESTS

Only requires a single visit to the clinic, while the skin test requires at least two visits

Results are objectively determined by a lab, while the skin test requires a subjective visual assessment

Higher test specificity than the skin test, reducing false positive results and unnecessary follow-up (i.e. chest x-ray)

Results are unaffected by the BCG vaccine , which confounds skin test results and is common among persons from high- burden countries

BLOOD TEST

Fortunately, QuantiFERON ® -TB Gold Plus , developed by QIAGEN ® , provides a testing solution that is more accurate in detecting LTBI than the traditional skin test. Facility administrators can strengthen their TB infection-control efforts by requiring TB testing with an IGRA like QuantiFERON-TB Gold Plus for an entire correction facility community. This approach not only limits the introduction of a TB outbreak in the facility, it is also useful for TB infection-control.

BLOOD TEST

SKIN TEST

One visit to the clinic

Two visits to the clinic

Tuberculin is injected into the skin

A small sample of blood is taken Results are unaffected by the BCG vaccine

Results may be affected by the BCG vaccine

Results are determined in a laboratory

Results are determined by subjective/ visual assessment

Though the general incidence rate of TB remains low, corrections facilities must adopt preventive measures to meet the challenges of TB infections. It’s important for facilities to implement proper protocols to ensure they are part of the public health response to TB, detecting and treating latent TB for the safety of residents, employees, and the greater community.

7. Lewinsohn, D.M. et al. (2017) Official ATS/CDC/IDSA Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children. Clin. Infect. Dis. 64, 111-115. 8. Katyal M. et al. (2018) “IGRA-Based Screening for Latent Tuberculosis Infections in Newly Incarcerated in New York City Jails.” Journal of Correctional Health Care. 24(2): 156-170. 9. Nijhawan A, et al. “Cost analysis of tuberculin skin test and the QuantiFERON-TB Gold In-tube test for tuberculosis screening in a correctional setting in Dallas, Texas, USA.” BMC Infectious Diseases. 2016: 16:564. DOI 10.1186/ s12879-016-1901-8

QuantiFERON-TB Gold Plus (QFT®-Plus) is an in vitro diagnostic aid for detection of Mycobacterium tuberculosis infection. QFT-Plus is an indirect test for M. tuberculosis infection (inclu-ding disease) and is intended for use in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations. The performance of the USA format of the QFT-Plus test has not been extensively evaluated with specimens from individuals who have impaired or altered immune functions, such as those who have HIV infection or AIDS, those who have transplantation managed with immunosuppressive treatment or others who receive immunosuppressive drugs (e.g., corticoste- roids, methotrexate, azathioprine, cancer chemotherapy), those who have other clinical conditions, such as diabetes, silicosis, chronic renal failure, and hematological disorders (e.g., leukemia and lymphomas).

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