Rats and Mice compete with humans for food. In some developing countries. It can cause starvation. Rodents are also hosts for human diseases, they transmit more than 131diseases including plague, urine typhoid fever, salmonellosis, Leptospirosis, Rat bite fever. Rats also occasionally bite people. In addition, they cause other damage, mainly by gnawing.
As far as possible, rodent populations should be controlled by limiting their access to food and shelter. Individual animals or small groups may be removed conveniently by trapping. However, there will always be a need for poisons in rodent control.