IFNG and influenza: Latent tuberculosis (positive purified protein derivative [PPD] or interferon-gamma release assays) was diagnosed more commonly in long-term than in short-term travelers (11 vs. 4/1,000; OR 3.26, p<0.0001), whereas influenza was diagnosed less commonly in long-term travelers (5 vs. 8/1,000, OR 0.60, p = 0.0183).