Epidemiology and Infection

  • Epidemiology and Infection / Volume 137 / Issue 05 / May 2009, pp 654-661
  • Copyright © 2008 Cambridge University Press 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/S0950268808001416 (About DOI), Published online: 08 October 2008