Handwashing
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Hands to food: germs are transmitted from unclean hands to food, usually by an infected food preparer who didn't handwash after using the toilet. The germs are then passed to those who eat the food.
Infected infant to hands to other children: during diaper changing, germs are passed from an infant with diarrhea to the hands of a parent; if the parent doesn't immediately wash his or her hands before handling another child, the germs that cause diarrhea are passed to the second child.
Food to hands to food: germs are transmitted from raw, uncooked foods, such as chicken, to hands; the germs are then transferred to other foods, such as salad. Cooking the raw food kills the initial germs, but the salad remains contaminated.
Nose, mouth, or eyes to hands to others: germs that cause colds, eye infections, and other illnesses can spread to the hands by sneezing, coughing, or rubbing the eyes and then can be transferred to other family members or friends.
Food to hands to infants: germs from uncooked foods are transferred to hands and then to infants. If a parent handling raw chicken, for example, doesn't wash his or her hands before tending to an infant, they could transfer germs such as salmonella from the food to the infant.
Handwashing can prevent the transfer of germs in all five of these scenarios. CDC recommends vigorous scrubbing with warm, soapy water for at least 15 seconds.