Epidemiology and Infection

  • Epidemiology and Infection / Volume 139 / Issue 07 / July 2011, pp 967-985
  • Copyright © Cambridge University Press 2011 The online version of this article is published within an Open Access environment subject to the conditions of the Creative Commons Attribution-NonCommercial-ShareAlike licence <http://creativecommons.org/licenses/by-nc-sa/2.5/>. The written permission of Cambridge University Press must be obtained for commercial re-use.
  • DOI: http://dx.doi.org/10.1017/S0950268811000574 (About DOI), Published online: 15 April 2011