Over the more than two years between December 2009 and March 2012, four serotypes of dengue were detected in Australian soldiers deployed to East-Timor. Some cases were not indicated by serological testing. We isolated a significant number of dengue viruses in Australian soldiers deployed to East-Timor, some representing infections that had not been reported from the field. Our data confirms the rapid displacement patterns of dengue virus that have been shown in other studies, demonstrating that accurate predictions of serotype re-emergence can be made on the basis of previous displacement data. A similar screening of sera from soldiers deployed to the Solomon Islands over the same period found no indication of dengue infection.