Microorganisms in food

According to a data review conducted by the FDA in 2015, viral pathogens account for an estimated 5.5 million foodborne illnesses each year, with norovirus responsible for most foodborne illnesses on an annual basis (58%) (Scallan et al., 2011).
Among the bacterial pathogens causing foodborne illnesses, the three most common are Salmonella spp. (11%), Clostridium perfringens (10%) and Campylobacter spp. (9%) (Scallan et al., 2011). Other bacterial pathogens causing relatively large numbers of illness include Bacillus cereus, E. coli O157:H7, non-O157 Shiga-toxin producing E. coli, Shigella spp., Staphylococcus aureus, and Yersinia enterocolitica (Scallan et al., 2011).

Source: Center for Food Safety and Applied Nutrition, Food and Drug Administration, U.S. Department of Health and Human Services, "Qualitative Risk Assessment: Risk of Activity/Food Combinations for Activities (Outside the Farm Definition) Conducted in a Facility Co-Located on a Farm", 2015