Studies on within-person variability of Interferon gamma release assays in high and low burden countries.

*India and South Africa are high prevalence TB countries with high risk of exposure to health care workers (HCW). HCW's were divided into two groups – medical doctors or laboratory workers.+South Africa is a high prevalence TB country with high risk of exposure to health care workers (HCW). HCW's were stratified into: High risk (daily potential TB exposure) Medium risk (HCW, but no daily expected TB exposure) Low risk group (pre-clinical medical students and non-clinical volunteers).#updated preliminary data presented at the Second Global Symposium on IGRAs. Daley C. Evaluation of interferon-g release assays in the diagnosis of latent TB infection in US healthcare workers: preliminary results of Task Order #18. 31 May 2009; Second Global Symposium on IGRAs, Dubrovnik, Croatia2009.