Athlete's Foot
The Athlete's Foot (tinea pedis) fungus sometimes has other manifestions with other names, but all are essentially caused by the same species of fungus. However, going barefoot is NOT what causes this fungus to spread. It's an oft-repeated myth that Athlete's Foot is contagious in this way. The spores appear to be generally available and just waiting for a ripe environment ... the hot sweaty insides of shoes. The main point is not how the spores are transmitted (dried fungal spores can float through the air) but HOW receptive is the host environment. The following is from the Athletes Foot pamphlet at the American Academy of Dermatology website.

Athlete's foot does not occur among people who traditionally go barefoot. It's moisture, sweating and lack of proper ventilation of the feet that present the perfect setting for the fungus of athlete's foot to grow.
It's commonly believed that athlete's foot is highly contagious -- that you can easily catch it from walking barefoot in the locker room. This is not true. Experiments to infect healthy skin with athlete's foot have failed and often one family member may have it without infecting others living in the same house.

The full pamplet is available here at the American Academy of Dermatology website.

So, having your child spend as much time as possible with their feet in the air and light will, in fact, greatly diminish the chance that athlete's foot will be able to take hold.

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