The movement of humans and the spread of Salmonella into existing and pristine ecosystems

The spread of infectious diseases by the international and national movement of people, animals, insects and products has a documented history dating back several centuries(1). The role of human movements has been fundamental to this, and has increased as global travel has risen in amount and speed. This has been exemplified by international epidemics of influenza, antimicrobial resistant bacteria, SARS coronavirus, dengue, chikungunya virus, Zika viruses and many others. Foodborne pathogens have also regularly come to our attention for their ability to move internationally, and outbreaks of salmonellosis due to importation of contaminated foods are well described(2,3). An extensive collection of non-typhoidal Salmonella and related species isolated from human, food, animal and environmental sources has been accumulated within Western Australia (WA) since the mid-20th century, and has proven an important historical source of information about the role of humans in the dissemination of microorganisms across and within diverse ecosystems(4-6). It is clear that the movement of microorganisms into and out of Australia is by no means a new phenomenon, and that humans have been important contributors to that spread. These are important markers of our impact on established and pristine ecosystems.