Rats are carriers of diseases via fleas (foot-and-mouth disease, typhus, plague, etc). They cause enormous damage by gnawing on doors, woodwork, beams, electrical wires and pipelines.
Mice can transmit a number of diseases to humans and livestock including:
• salmonella to humans and domestic animals
• encephalomyocarditis (EMC) virus to pigs
• leptospirosis to humans, dairy cattle and domestic pigs
• tapeworms, roundworms and fungal skin diseases (ringworm) to cats and humans.
Mouse droppings can also cause bacterial poisoning of human and livestock foods.
The damage caused by plagues of mice is enormous. They will attack virtually all cereal and grain crops, plus many vegetables and fruits.
It should be stressed that a mouse plague, while it may arise from seasonally variable conditions, is not necessarily limited to a season's duration. Plagues have been known to last through a mild winter into the following growing year. The damage from plagues can then run into millions of dollars.