Terms of Use for Article Epidemiol Infect. 2016 Jan 22; 144(2):225-233 Read the license and copyright statements in the XML or PDF files for this article before reusing or redistributing any part of the article. The license and copyright statements define what uses of the article are permitted, and apply to all associated files, including images and supplementary material. The terms and conditions of use are not identical for all articles. Contact the publisher if you have any questions about the permissible uses of the article.