A lot of it is from cross contamination with other snakes, we have always had a policy that if we visit somewhere with reptiles whether its a shop or a private house when we return home we strip and put all clothes in the washer and then we shower before going near our own reptiles.
May be slightly extreme but we have had no mites in two years
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May you have more good days than bad

You never know how strong you are - until being strong is your only choice
There are no dark clouds - just well hidden silver linings!!