What role do harmful microorganisms play in foodborne illness?

Harmful microorganisms, such as bacteria, viruses, and parasites, are the primary agents that cause foodborne diseases. When these pathogens contaminate food or water, they can multiply and produce toxins, leading to various health issues upon consumption. Symptoms can range from mild gastrointestinal discomfort to severe illness or even life-threatening conditions, depending on the type of microorganism and the individual's health status. Understanding this role is crucial in implementing proper sanitation and safety practices to prevent foodborne illnesses and protect public health. The other options, while they may describe the roles of certain benign microorganisms (like some used in fermentation or food preservation), do not pertain to the harmful effects associated with foodborne illness.