Final answer:
Prions are another cause of foodborne illnesses, along with bacteria, viruses, parasites, and mold.
Step-by-step explanation:
Foodborne illnesses can be caused by a variety of microorganisms, toxins, or adulteration of food by foreign bodies. Apart from bacteria, viruses, parasites, and mold, another cause of foodborne illnesses is prions, which are responsible for diseases like mad-cow disease. These prions can be transmitted to humans through the ingestion of contaminated beef.