Just as an example of a superstition, take the "Virgin Cleansing Myth". It's a myth existing all over the world, by especially prevalent in Africa, that having sex with a virgin will cleanse you of diseases, especially nowadays HIV. [1]

This is believed by some to be one of the reasons why HIV, and rape, is so prevalent in South Africa - people with HIV will often rape virgins to cure themselves, thus also spreading the disease.

[1] - https://en.wikipedia.org/wiki/Virgin_cleansing_myth