I mean, depending on where you live in the world, a lot of infectious diseases can spread by either wounds on the hand or vectors invading through the palm of the hand.
GAHHHHH! All the children must wear hand-shoes all the time!! Otherwise they'll all die! Maybe we adults (alleged adults. I refuse to believe I am one.) should too.
/s
You're just being silly and worrisome.
edit: to be less vague:
(1) Tetanus spores are present in soil all over the world and can easily infect a cut on the foot - between 1 and 2 in 10 cases are fatal (https://www.cdc.gov/tetanus/index.html).
(2) Hookwork larvae are present in soil all over the USA (and many other places) and can infect through intact skin - not fatal but can have unpleasant complications (https://www.cdc.gov/parasites/hookworm/)
(3) bilharzia infects through skin contact with contaminated water which includes puddles and just wet soil - not in the USA but many other countries - and kills tens of millions every year (https://www.cdc.gov/parasites/schistosomiasis/index.html)
What's wrong with kids running around barefoot?