Gerald is Associate Dean Clinical at The University of Queensland and Director of Gastroenterology and Hepatology at the Princess Alexandra Hospital in Brisbane.

In 2004, Gerald was appointed Director of Gastroenterology & Hepatology at the Royal Adelaide Hospital, and Professor of Medicine at the University of Adelaide. He is also a Fellow of the Royal College of Physicians in London and fellow of the Royal Australasian College of Physicians. Gerald's research is focused in the field of Neurogastroenterology and has continuously attracted peer reviewed funding from national and international funding bodies such as the National Health and Medical Research Council (NHMRC) and the German Research Foundation.

He has published more than 300 articles and book chapters in leading journals including the NEJM, Lancet and Gastroenterology. Besides his clinical and academic activities, Gerald completed a Master in Business Administration (MBA) at the University of South Australia.