Why are rats considered pests?
The presence of rodents and mice within buildings is usually undesirable from the viewpoint of food spoilage and contamination, physical damage and the transmission of diseases to humans.
Eating and contamination of stored foods - Rants and mice are responsible for enormous losses of food in storerooms either by directly eating the food or rendering it unusable through contamination. As the rodent moves in and around stored food areas they contaminate the food with droppings, urine and hair.
Gnawing Physical Damage – The constant gnawing of rodents can be the cause of serious damage to a range of materials. Typically they may damage doors, skirting and other parts of building upholstery, books, food containers and parts of equipment and machinery. The gnawing of wires and cables has caused the breakdown of telephone systems and short circuiting which may result in equipment break down or even fires in rare situations.
Disease Transmission – Historically the role that rats and mice have played in the transmission of diseases has been of profound importance. Known as the Black Death, Bubonic plague has claimed more that 25 million lives in the 14th century Europe is perhaps the most demonstrated case. Among the many disease transmitted to humans by rodents perhaps, the most sinister and widespread problem involves the distribution of food poisoning organisms eg. Salmonella bacteria.
Gerozisis, John, and Phillip Hadlington. Urban Pest Management in Australia. Sydney: UNSW Press, 2001. N. pag. Print.