Wild animals harbour a diverse range of pathogens. In Europe and North America, cervids (Family Cervidae) can act as reservoirs for viral, prion, bacterial, and parasitic infections. Wild deer often inhabit agricultural land, therefore representing a biosecurity risk due to their potential ability to transmit diseases to livestock. Multiple studies have investigated the infection status of wild deer in Australia, mostly during the 1970s and 1980s, and deer populations have increased greatly in abundance and distribution since then. Those studies provide an important baseline for the pathogens carried by wild deer in Australia but are limited by small sample size, the small number of deer species studied, and the disease detection methods used. Recent investigations using ELISA (Enzyme-Linked Immunosorbent Assay), PCR-based assays, and next-generation sequencing have substantially increased our understanding of viral and parasitic infections in Australian deer. These studies indicate that deer may act as reservoirs for pathogens such as Pestivirus, Neospora caninum and Entamoeba bovis. The use of next-generation sequencing has led to the discovery of novel viruses such as Picobirnavirus and a novel species of the genus Bopivirus, both of which pose transmission risks for domestic animals. Recent research confirms that wild deer could be a future source of viral and parasitic infections for domestic livestock and other wildlife species.