Human and animal feces contain germs such as Salmonella, E. coli O157, and norovirus which can cause diarrhea. Furthermore, adenovirus and hand-foot-mouth disease can be spread through respiratory infections.
People run the risk of coming into contact with these organisms after using the restroom or changing a diaper; handling raw meat can also lead to contamination due to the presence of invisible feces particles.
A single gram of human feces contains one trillion germs on average. Germs can accumulate on hands if they come into contact with an object that has been exposed to droplets from a cough or sneeze or is otherwise contaminated. If left uncleaned, these germs can easily be passed between people, resulting in illness.