The presence of rats and mice in buildings is usually regarded as undesirable from the viewpoint of food spoilage and contamination, physical damage, and the transmission of diseases to humans. There are 3 types of common pest rodents. The small House Mouse, medium-sized Roof Rat and large Norway Rat.

Eating and Contamination of Stored Food

Rats and mice are responsible for enormous losses of food stores, either by directly eating the foods or by rendering them inedible through contamination. As the rodents move in and around stored foods, they contaminate the food with dropping and hairs.

The constant gnawing of rodents can cause serious damage to a range of materials. Typically, they may damage doors, skirtings and other parts of buildings, upholstery, books, food containers or packaging. The gnawing of wires and cables has caused the breakdown of phone systems and short-circuiting, which may result in equipment breakdown or, at worst, very costly fires. Fire damage has also resulted from the gnawing of matches collected in the nest.

Disease Transmission

Rats & mice may transmit disease to humans by a variety of means:

  1. Contamination of food or utensils with rodent urine or faeces, e.g. Salmonella, Choriomeningitis, Tapeworm
  2. Contamination by direct contact with the urine or faeces, where bacteria seem to enter the skin through small scratches, e.g. Weil’s Disease.
  3. Indirect contamination via blood-sucking insects (rat fleas), e.g. Plague, Murine Typhus Fever.
  4. Indirect contamination via pets to humans, e.g. Favus, Skin disease
  5. Contamination by directly biting humans, e.g. Rat Bite Fever, Relapsing Fever Bacteria
  6. Indirect contamination by being eaten by an intermediate carrier, e.g. Trichinosis.

House rats & mice in buildings pose a serious threat to human health. The disease threat alone is a justifiable cause for concern and for the implementation of sound control procedures.