PURPOSE: To use Quanti-feron TB ® (QFT) as an aid to diagnose tuberculosis (TB) infection in a field-based targeted TB testing and treatment program (TTP) amongst foreign-born persons in Suffolk County, New York.
METHODS: In 2003, the TTP used QFT instead of the tuberculin skin test (TST) as an aid to diagnose TB infection in two groups of participants (110 persons) a TTP amongst foreign-born persons.
RESULTS: There were 31% QFT positive (34/110) reactors in the two groups tested. This number compared favorably with the TST positive rate of 36% (426/1193) for the entire TTP.
CONCLUSION: The QFT assay gave comparable positivity rates to the TST in this foreign-born population. This is not surprising as this generation of the QFT assay used PPD as a test antigen. All patients tested with QFT had a result, there was no need for a second visit as is required for reading and interpreting the TST. The logistical management of our field-based TTP was simplified and improved because the exact number of positive reactors was known prior to our initial field-based clinic at which a medical evaluation, chest radiography and initiation of treatment for latent TB infection (LTBI) were done. This enabled the TTP to assess our logistical needs in certain areas (e.g., the number of x-ray cassettes our portable x-ray contractor needed to bring to the site of our initial field-based clinic, etc.) prior to the clinic. This would have been impossible using the TST to diagnose LTBI because the number of positive reactors is unknown until TST reading takes place in the field whereas with QFT assay the number of positive reactors is known after the assay has been resulted from the laboratory. This simplified the logistical management of our field-based TTP.
CLINICAL IMPLICATIONS: QFT or other blood assays for Mycobacterium tuberculosis may be prove useful in other field-based TB control activities because it simplifies and improves the logistical management any of field-based operations that require testing for and treatment of LTBI.
DISCLOSURE: Lewis Mooney, No Financial Disclosure Information; No Product/Research Disclosure Information