“Should the Doctor Shake a Patient’s Hand?”

Dirty hands can transmit many types of infection. If you think shaking hands is a friendly gesture, thing again. It is a well-known health hazard. Dirty hands can transmit infections such as noroviruses and salmonella that cause diarrhea and vomiting, rhinoviruses that can give you a cold, as well as the viruses that cause flu and chickenpox. Diseases that spread rapidly and can be fatal, such as methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile, can also lurk on hands. The bugs can be transferred to surfaces and door handles for other people to share. So, should we keep our hands to ourselves? These days, hospitals and offices are oozing with indestructible bacteria and patients are trigger-happy with lawsuits over perceived offenses. When you shake hands with someone, you’re greeting dozens, if not hundreds, of species of bacteria. In one study, researchers found that the typical person’s hand has more than 150 distinct species of bacteria living on it. And the bacteria are diverse. The microbes on the other person’s hand are vastly different from the ones on your hand. Specifically, researchers found more than 4,700 different bacteria species among 102 human hands, with just 5 species shared among all participants—a commonality of only 13%. Even your right hand has only 17% of the same bacteria as your left hand, the researchers found. Surprisingly, the researchers also showed that the overall diversity of bacteria on individual hands was not significantly affected by regular handwashing. Either the bacterial colonies rapidly re-establish after hand washing or washing does not remove most bacteria found on the skin surface. Still, that’s no excuse to skip washing your hands.

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