Rodents

Different ways...

Rats and mice are known carriers of several microorganisms that can cause disease in cattle. Particularly dangerous for lifestock is the transmission risk of bacteria of the genuses Salmonella, Leptospira, Yersinia, Ricketsiae, as well as some viruses. Weils's Disease (caused by Leptospira icterohaemorrhagiae) is a disease afflicting cattle and pigs; it can also affect humans, and is in fact, an occupational disease among persons involved who come into direct contact with infected animals, soil or water contaminated with rats' urine. The transmission of bovine brucellosis, the most common species being Brucella abortus, is also attributed to rats. There is evidence that wild rats in the U.K. could constitute an significant reservoir of Coxiella burnetti, the rickettsia causative of Q-fever in dairy farmsteads. This disease is currently considered the most serious and potentially chronic zoonosis transmissible to humans from lifestock animals through the air. Yersiniosis (pseudotuberculosis) is also associated with the presence of rats in farms. There is also a number of lifestock diseases in which the role of commensal rodents is not yet clear, however various causative microorganisms have been isolated from commensal rodents which lead to tuberculosis, vibriosis, listeriosis, foot and mouth disease, etc.

...of rodent control

Rodents can also cause severe damage to humans through loss of foodstuffs being consumed and/or contaminated by rats' urine, saliva and droppings. Rats contaminate at least three times as much food as they eat themselves!

Rats can also cause structural damage through their burrowing and gnawing habits. They can severely weaken the foundations of farm buildings.