Earlier, I was all sarcastic about some advice on protecting your child from syphilis by making sure that no visiting relatives have it. But in the 1920 book The care and feeding of children: a catechism for the use of mothers and children’s nurses, page 195:

“Are there any valid objections to kissing infants?
There are many serious objections. Tuberculosis, diphtheria, syphilis, and many other grave diseases may be communicated in this way. The kissing of infants upon the mouth by other children, by nurses, or by people generally, should under no circumstances be permitted. Infants should be kissed, if at all, upon the cheek or forehead, but the less even of this the better.”

Jeez! How long did this myth persist? “No, really, honey, I got it from kissing a baby!”

Later note: OK, turns out I wasn’t paying enough attention in health class. Syphilis can be passed by kissing if the sores are on the mouth. Never again will I mock old medical or child-rearing advice.