The worldwide spread of drug-resistant strains of tuberculosis (TB) bacteria is out of control and incidents of harder-to-cure TB illness are rising. This article explores the present and potential impact of extensively drug-resistant tuberculosis (XDR-TB) – a deadly, contagious and virtually incurable disease – on human health and state capacity. Detected cases of XDR-TB can occasion the implementation of extraordinary control measures, because some governments are sufficiently fearful of the disease as to frame it as an issue of national security. Such framing has the potential to precipitate more financial resources and stronger legal powers to bolster public health, but it might also increase the risk that emergency response measures will be counterproductive and/or unjust. Framing XDR-TB as a security issue is empirically plausible, and doing so is a good thing provided that increased response efforts promote rather than hinder the provision of universal access to adequate TB treatment over the long term. Two disease-control measures that are motivated particularly by security concerns are: border control and patient isolation. The article offers an assessment of each measure by reference to public health ethics in order to differentiate good and bad securitization.