If mice get into a person's food or water supply, he or she can be infected with Salmonella, develop tapeworms, contract infectious jaundice or Lymphocytic choriomeningitis. Mites found on mice can also cause problems such as house mouse mite dermatitis, or Rickettsial pox.
Rodent pests can cause considerable damage to your home while contributing to the unsanitary aspect of it. Especially in households with children who are more susceptible to illness.
The main problems with wildlife in your yard will likely be the destruction that animals can cause while they try to eat everything edible they can find in your yard and the damage they cause while they try to nest in your house and yard.