In this article, the fifth in a series reviewing the role of food workers in foodborne outbreaks, background information on the routes of infection for food workers is considered. Contamination most frequently occurs via the fecal-oral route, when pathogens are present in the feces of ill, convalescent, or otherwise colonized persons. It is difficult for managers of food operations to identify food workers who may be excreting pathogens, even when these workers report their illnesses, because workers can shed pathogens during the prodrome phase of illness or can be long-term excretors or asymptomatic carriers. Some convalescing individuals excreted Salmonella for 102 days. Exclusion policies based on stool testing have been evaluated but currently are not considered effective for reducing the risk of enteric disease. A worker may exhibit obvious signs of illness, such as vomiting, but even if the ill worker immediately leaves the work environment, residual vomitus can contaminate food, contact surfaces, and fellow workers unless the clean-up process is meticulous. Skin infections and nasopharyngeal or oropharyngeal staphylococcal or streptococcal secretions also have been linked frequently to worker-associated outbreaks. Dermatitis, rashes, and painful hand lesions may cause workers to reduce or avoid hand washing. Regardless of the origin of the contamination, pathogens are most likely to be transmitted through the hands touching a variety of surfaces, highlighting the need for effective hand hygiene and the use of barriers throughout the work shift.