Human Salmonellosis: A Continuous Global Threat in the Farm-to-Fork Food Safety Continuum

Abstract

<i>Salmonella</i> is one of the most common zoonotic foodborne pathogens and a worldwide public health threat. <i>Salmonella enterica</i> is the most pathogenic among <i>Salmonella</i> species, comprising over 2500 serovars. It causes typhoid fever and gastroenteritis, and the serovars responsible for the later disease are known as non-typhoidal <i>Salmonella</i> (NTS). <i>Salmonella</i> transmission to humans happens along the farm-to-fork continuum via contaminated animal- and plant-derived foods, including poultry, eggs, fish, pork, beef, vegetables, fruits, nuts, and flour. Several virulence factors have been recognized to play a vital role in attaching, invading, and evading the host defense system. These factors include capsule, adhesion proteins, flagella, plasmids, and type III secretion systems that are encoded on the <i>Salmonella</i> pathogenicity islands. The increased global prevalence of NTS serovars in recent years indicates that the control approaches centered on alleviating the food animals' contamination along the food chain have been unsuccessful. Moreover, the emergence of antibiotic-resistant <i>Salmonella</i> variants suggests a potential food safety crisis. This review summarizes the current state of the knowledge on the nomenclature, microbiological features, virulence factors, and the mechanism of antimicrobial resistance of <i>Salmonella</i>. Furthermore, it provides insights into the pathogenesis and epidemiology of <i>Salmonella</i> infections. The recent outbreaks of salmonellosis reported in different clinical settings and geographical regions, including Africa, the Middle East and North Africa, Latin America, Europe, and the USA in the farm-to-fork continuum, are also highlighted.