These are some of the interesting names for small microorganisms that can cause big health problems when consumed in contaminated foods or beverages. The world of foodborne microbes contains a mix of approximately 250 different types of bacteria, viruses, parasites, molds, and algae that are known to cause disease in humans and are therefore called foodborne pathogens. What they all have in common is that they are most often too small to be seen without a microscope, they have simpler structures and functions than higher plants and animals, and they are able to be cultured in laboratory settings with prescribed methods that aid in their identification. Bacteria are the largest group of problematic foodborne pathogens by far. They are small, one-celled microbes that come in many shapes and are capable of reproducing themselves. Viruses are thought to be the leading cause of foodborne illness in the United States based on the percentage of people ill, even though there are only a few viruses that are important foodborne pathogens. Viruses are much smaller than bacteria and cannot live outside a host, such as an animal or the human body.