Rodents

Rodents cause extensive damage all over the world because they destroy both human food and feed for animals. Both rats and mice are responsible for these kinds of losses. The damage rodents cause is not just a loss of food. The animals gnaw and contaminate goods and make them un-appetizing and unsaleable (three times the amount of stored products eaten by rodents is contaminated by them). If rats or mice gnaw one tiny hole in a sack of grain, the entire contents can no longer be eaten by people and at best can only be used for animal feed. Rodents destroy other materials, too, even plastics (electric cables) or metal. Add to that the damage they cause before harvest, e.g., in rice, corn and coconut fields.

Certain rodents have spread throughout all continents as a result of global trade and the movement of goods. Three key species are the most significant pests: the Norway rat (Rattus norvegicus), the black rat (Rattus rattus) and the house mouse (Mus musculus). These rodents are not only found in the tropics (where they came from), they are also found in temperate and cold climates.

There, they have followed human civilization and permanently live in human homes (black rat, house mouse) or move in during colder months (Norway rat). Poorly built buildings are open invitation for these rodents. They enter apartments, animal stalls or storerooms through cracks and openings to search for food.

Plague
The “Great Plague” of London killed half the city’s population. In the 14th Century, the “Black Death” of Europe lasted 50 years and killed 25 million people.

In the first quarter of the last century, an estimated 11 million people died in Asia from plague. The pathogen is transmitted to people primarily by the oriental rat flea. The flea bites an infected rat, and then, by feeding on humans, inoculates people with the bacteria that cause the disease. Although no global outbreak of plague has occurred since 1924, this is not a disease of the past. Plague still exists in several areas of the world.

Murine typhus is a relatively mild disease in humans. As with plague, murine typhus is transmitted from rats to humans by a rat flea. In this case, however the disease organism enters the bloodstream when feces of infected fleas are scratched into a flea bite.

Rodents are intelligent animals that can adapt well to new circumstances. But they are very wary of changes in their territory.