Former Director of the WHO Collaborating Centre for the Collection and Dissemination of Data on Virus Diseases of South-East Asia and the Western Pacific in the Department of Microbiology at The University of Western Australia from 1984 to 1994. Member of the steering committee of the Global Outbreak Alert and Response Network of the World Health Organization from 2002-2016 (Chair in 2009-10), and the Asia-Pacific Strategy for Emerging Diseases 2005-2016. Chaired the WHO International Health Regulations Emergency Committee for Pandemic H1N1 influenza in 2009-10, was a member of the Emergency Committee for COVID-19, and currently a member of the Emergency Committee for the Transmission and International Spread of Poliovirus. In 2003-04 he worked as a temporary Medical Officer at WHO to support post-SARS response efforts. Led a WHO mission into China investigating the origin of SARS in March 2003, and was a member of the WHO Indian Ocean Tsunami response team in Aceh in early 2005. Was a member of the initial term of the FAO-UNEP-WHO-WOAH One Health High Level Expert Panel until the end of 2023. He continues to be a member of the WHO Roster of Experts.

With his colleague, Prof Martyn Jeggo, initiated the International One Heath Congresses, the first being held in Melbourne in 2011. In 2015, co-founded the One Health Platform, a non-profit Foundation based in Belgium, and its successor, the Global One Health Community also based in Belgium, with his colleague Prof Albert Osterhaus, which have been responsible for the recent International One Health Congresses, of which the 8^th was held in Cape Town in 2024, and the next will be held in Lisbon in September 2026. He was elected as a Fellow of the American Academy of Microbiology in 1996 and was elected as a Fellow of the Australian Academy of Technological Sciences and Engineering in 2015. In 2002, appointed as Officer in the Order of Australia for services to microbiology research, particularly as a leading contributor in the understanding of the genetics, pathogenesis and public health implications of viruses, and to education. Recipient of various awards including the inaugural winner of the Akademi Sains Malaysia’s Mahathir Science Award for Excellence in Tropical Research; the Distinguished Service Award and Life Membership of The Australian Society for Microbiology; and the Excellence in Virology Award of the Asian-Pacific Society for Medical Virology Elected as a Distinguished International Fellow of the American Society of Tropical Medicine and Hygiene in 2021 and Distinguished Member, World Society for Virology in 2018

Served on a number of international and Australian committees, including as the Secretary-General of the International Union of Microbiological Sciences from 1999 to 2005; President of the Australian Society for Microbiology from 1992 to 1994, Foundation Member of the Executive Board of the Asian-Pacific Society for Medical Virology (President 2000-03); on the United Nations Group of Specialised Experts to Advise on Updating the Technical guidelines and Procedures for the Alleged Use of Chemical and Biological weapons (2007-08); on the Australian National Arbovirus and Malaria Advisory Committee; on the Australian National Certification Committee for the Eradication of Poliovirus; on the Strategic Science Advisory Panel of the Crown Research Institute of Environmental Science and Research, New Zealand (2011-2017); and on the Technical Reference Group of the Australian Department of Foreign Affairs and Trade’s Indo-Pacific Institute for Health Security.

His research has largely been directed at understanding the ecologies of mosquito-borne arboviral diseases and on factors and drivers of disease emergence. He has published widely on Japanese encephalitis, Murray Valley encephalitis, West Nile and Ross River viruses, and the ecological factors in their epidemiology and spread. Since he retired in 2008, he has been closely involved in developing the concept of One Health, an integrated, unifying approach that aims to sustainably balance and optimize the health of people, animals and ecosystems, recognising that the health of humans, domestic and wild animals, plants, and the wider environment (including ecosystems) are closely linked and inter-dependent.