Brown Rat

Brown Rat (Rattus norvegicus)

Taxonomy

It belongs to rodents (Rodentia), which are an order of placental mammals, which includes many species. Of these, the species of particular health interest are the so-called symbiotic rodents, which include mice. Mice belong to the family Muridae, where the genus Mus is classified. Main species of mice are Rattus norvegicus (Norway Rat) and Rattus rattus (Brown Rat) and the house mouse Mus musculus. All three species are particularly widespread in Greece.

Rattus Norvegicus

This species gives birth to 8-12 pups per litter, which are amenable to fertilization after 2 to 3 months, often earlier. On average the female gives birth 7 times per year, with a lifespan that can exceed 12 months.

It has a large robust body, with a coat that is brown, slightly black on top and gray to yellowish white on the bottom. The average body weight for adults is 300 grams and its body length ranges from 19 to 25 cm. Generally, it moves within a radius of 15-30m from the nest.

Public health

This is a group of mammals of enormous importance to humans, responsible for a large number of deaths. In addition to Weil’s Syndrome (leptospirosis), many species of mice are potential carriers of other serious diseases, including salmonellosis, plague, typhoid fever, and some forms of encephalitis. They also cause serious food contamination and allergies while they are carriers of parasites such as mites, nematodes, cestodes and insects.

In addition to the above effects on Public Health, symbiotic rodents cause serious destruction and damage to electrical and building installations. Rodents can even be responsible for a facility fire.

Modes of Management

Prevention: There should be no openings (eg open windows and doors, open drains, holes in walls). Special attention is paid to the cleanliness of the area (eg removal of rubbish and food sources) and in large outdoor areas (gardens, fields) weed killer is applied. Flower beds in contact with the external walls of factories and related facilities should be avoided.

Follow-up: The organization and implementation of an integrated rodent management program follows certain stages of actions, which are schematically:

Site research. Rodents need water, food, accommodation (nest) and relative quiet. The research of the area is therefore oriented towards the main points that offer these conditions. With the survey, the hearths, nests, routes are mapped.

Identification of species – Extent of infestation: Investigating these points, after careful observation (feces, footprints, tracks, etc.) on the one hand, and after using various means of presence control (detection dust, glue traps , mechanical traps, etc.) on the other hand, the species endemic to the area and the extent of the infestation are identified (specified).

Monitoring should take place at regular intervals to indicate the presence of symbiotic rodents.

Treatment: In order to combat symbiotic rodents, approved security bait stations are used that are placed in the points – zones that have been mapped in the area, with special warning, information (product and antidote) and inventory of findings marking exactly at the point of their placement. Approved rodenticide baits are placed at the bait stations which are anticoagulants of subacute toxicity that act on the blood (prothrombin cycle). These rodenticide baits are available in the form of cubes (waxed or not), paste, solids (pellets, shrimps), ground cereals, seeds and powder.

Particular care is needed when a symbiotic rodent control program is implemented in food industries where only presence control measures (eg mechanical multi-capture traps) are taken within the warehouse and production area, as the use of anticoagulants is not allowed.

Also, the role of the bait station is important and it should consist of hard plastic that does not contain toxic substances, be resistant to ultraviolet radiation, lock securely and have special places to securely fix the bait to avoid its dispersion. The collection and burning or burial of the corpses, as well as the collection of the remains of the baits used or to be replaced are necessary actions that must be done meticulously, diligently and in the legal way. In this context, free adhesive surfaces in various parts of production or warehouses are not a viable solution as they collect dust and foreign bodies while if a rodent is caught, it is fully exposed and a serious microbiological risk. An even worse option is the use of bulk rodenticide baits, which are a valid chemical hazard while also threatening non-target animals.