Religious festivals attract a large number of pilgrims from worldwide and are a potential risk for the transmission of infectious diseases between pilgrims, and to the indigenous population. The gathering of a large number of pilgrims could compromise the health system of the host country. The threat to global health security posed by infectious diseases with epidemic potential shows the importance of advanced planning of public health surveillance and response at these religious events.

We welcome your Editorial plea ('Orphan giant' Nature 459, 1034; 2009) for stronger advocacy for tackling tuberculosis (TB), a shared global strategy and increased commitment to research and innovation. The emerging threat of drug-resistant TB in Europe, highlighted in a recent report from the European Academies Science Advisory Council (EASAC; http://www.easac.eu. (Correspondence)