It is becoming more available in the US and indeed in other countries. eg Japan have recently abandened their PPD testing resorting to annual X rays to test their various populations until quantiferon TB Gold was approved last year and is now being recommended in their updated guidelines. In the US, Sanfrancisco were the first city to completely switch to the first version of quantiferon and more recently to the Quantiferon TB Gold for certain populations such as the homeless. They are now extending their testing to a wider population as logistics expand in the laboratory.
A newer version, quantiferon TB Gold Intube, is currently being evaluated and under FDA approval which removes the 12 hour limit of getting blood samples to the LAB. This version has special tubes to collect the blood sample and the antigens begin reacting immediately, thus making the test more sensitive. The USAF are currently evaluating this version. They are looking at replacing their PPD testing of soldiers with the quantiferon test. So over the coming years you will find this test being used more often in situations where the PPD has its problems of false negatives and false positives.
It is certainly worthwhile having a quantiferon test if available in your area prior to beginning a regime of TB treatment to confirm the PPD diagnosis. This is where the big savings are being experienced as resources are not being wasted treating people wrongly diagnosed as having TB.
I believe the test is offered in a growing number of labs and hostipals around the country. Some that I know of are
San Francisco Dept Health Labs
Nabraska University medical Centre (www.nphl.org/documents/TBInterferon2.pdf
Texas Department of State Health Services (www.dshs.state.tx.us/lab/refman.pdf
There are at least 40 major health departments, universities and labs offering the quantiferon TB test as a service. Over the coming years it will become available in all states and counties in the same manner as other blood tests. Check with your local health department for more information.