April 11, 2007
A large contact study has found that two new interferon-gamma blood test assays can detect latent tuberculosis infection exposure better than traditional tuberculin skin tests.
The results were published in the second March issue of the American Journal of Respiratory and Critical Care Medicine.
The blood tests detected the infection of supermarket customers in Holland where an employee had smear-positive tuberculosis.
More than 20,000 customers who shopped at the supermarket for more than 10 months had contact with the infected employee, who had been contagious since February 2004. The large-scale contact investigation began in January 2005.
The skin test results were associated with age, while the blood test results were significantly associated with cumulative shopping time the study found. The study did not reveal which test was better at detecting whether someone exposed would develop TB.
One of the two blood tests has been approved for use in the United States, the other for Europe.