So you are a farmer too, Fred! You are fortunate your dogs (or are you arable?) have never contracted sarcoptic mange (it's called "scabies" in people by the way- are you sure you've never heard of it?), because it takes up to 6 months of vet treatment to cure it. Our local foxhounds are regularly dipped against it as a preventative measure. As for the other diseases: toxocariasis can cause liver and eye disease in people, and is what the tabloid press have a regular 'hissy-fit' about, and echinococcosis ("Hyatid disease" in man) causes liver, lung and brain cysts. Unless the foxes in your locality are regularly wormed, they are likely to be carrying all these problems. Rural foxes are generally healthier than urban ones, mainly due to their lower population density, but a responsible person needs to be aware of the risks to know what action to take in the event of their own or their animals' illness. PS - I forgot Leptospirosis ("Weil's disease") which can be fatal to both dogs and people.