Roof rats and mice have a long history of disease transmission in the human population. It is also true that their risks to poultry health are nearly as bad. Rats are known to harbour diseases like Salmonella and fowl cholera, and because they travel back and forth from contaminated poultry bedding to feeders and drinkers, these rodents are potential mechanical vectors of both parasitic and bacterial diseases of poultry.
Besides transmitting diseases, they also consume poultry feeds and destroy water lines and electrical installations, thus causing huge financial losses to farmers. Due to their migration habits, they may introduce diseases and parasites from nearby farms and, at the same time, make it much harder to restrict a disease problem to one house on a farm.