An outbreak of measles in Sydney has been predominantly linked to return travellers from Southeast Asia.A report from NSW Health said of the 60 cases of the highly infectious disease seen in the state since the start of last year, over half had come from people who had travelled in the region.While Australia has officially been measles-free since 2014, it is common in several Southeast Asian countries, including Indonesia, which is a popular tourist destination for Australians.LIVE UPDATES: Fireball after