Public Health Vectors and Pests


Common Name House Mouse
Scientific Name Mus musculus
Size Adult are 12-30g and the tail is 60-105mm
Colour Brown to black, belly fur white, brown or grey.  The colour of the tail is lighter below than above.
Description House mouse is a small, slender rodent that has a slightly pointed nose, small, black, protruding eyes; large sparsely haired ears and a nearly hairless tail with obvious scale rings.
Habitat They are specially found in areas that are near human habitats and open fields

House mice live in houses; out buildings, stores, and other structures. In favourable conditions, feral mice may be found in fields, along water courses and in place with dense vegetation where they can hide in. These feral animals make runways through the grass. House mouse is regularly found along irrigation ditches where irrigation is practiced, in agricultural areas.
Lifecycle House mouse has an extremely high breeding potential with the female house mouse becoming sexually mature at six weeks. After mating, gestation lasts 19-21 days and immediately after giving birth, mating is possible. In ideal conditions a mouse can give birth every 25 days.
Disease Transmitted Lymphocytic choriomeningitis (LCM)
Symptoms An initial phase may last for a week. It begins with any one of the following; fever, lack of appetite, muscle pains, headache, nausea, and vomiting. Other symptoms that seldom appear include sore throat, cough, joint pain, chest pain, testicular pain, and parotid (salivary gland) pain. After a few days of recovery, the second phase of the disease occurs, consisting of symptoms of meningitis (for example, fever, headache, and a stiff neck) or characteristics of encephalitis (for example, drowsiness, confusion, sensory disturbances, and/or motor abnormalities, such as paralysis). LCMV has also causes acute hydrocephalus (increased fluid on the brain). In rare instances, infection results in myelitis (inflammation of the spinal cord) and presents with symptoms such as muscle weakness, paralysis, or changes in body sensation. An association between LCMV infection and myocarditis (inflammation of the heart muscles) has been suggested.

During the first phase of the disease, the most common laboratory abnormalities are a low white blood cell count (leukopenia) and a low platelet count (thrombocytopenia). Liver enzymes in the serum may also be mildly elevated. After the onset of neurological disease during the second phase, an increase in protein levels, an increase in the number of white blood cells or a decrease in the glucose levels in the cerebrospinal fluid (CSF) is usually found.

Type of Damage
  • When house mice live in or around buildings, they almost always cause some degree of economic damage. In homes and commercial buildings, they may feed on various stored food items or pet foods. They usually contaminate foodstuffs with their urine, droppings, and hair. On farms, they may cause damage to feed storage buildings and feed transporting equipment. A single mouse eats merely about 3 grams of food per day (3.6 kg per year) but it considerably destroys more food than it consumes because of its habit of biting off small bits on many foods and discarding partially eaten items.
  • House mice living in fields may dig up and feed on newly planted grain, or may cause some damage to crops before harvest There are great losses in stored food. They are notorious of damage containers and packaging materials in warehouses where food and feeds are stored. Much of this loss is due to contamination with droppings and urine, making food to be injurious to human health.
  • House mice cause structural damage to buildings by their biting on persistently and nest-building activities. In livestock lairages and similar structures, they may readily cause severe damage to insulation inside walls and attics. Such damage also occurs in homes, apartments, offices, and commercial buildings but usually at a slower rate because in such buildings mouse populations are small. House mice often lodge in large electrical appliances, and here they may chew up wiring as well as insulation material, resulting in short circuits which create fire hazards or other malfunctions that are costly to repair. Mice may also damage stored items in attics, basements, garages, or museums, zoo. Damaged family heirlooms, paintings, books, documents, and other such items may be impossible to replace.
Sources / Breeding Mus musculus is identified by remarkable reproductive potential. Breeding occurs throughout the year. The oestrous cycle is 4-6 days long, with oestrus lasting less than a day. Females experience a postpartum oestrus 12-18 hours after giving birth. Females generally have 5-10 litters per year if conditions are favourable. Gestation is 19-21 days but may be extended by several days if the female is lactating. Litters consist of 3-12 (generally 5 or 6) offspring, which are born naked and blind. They are fully furred after 10 days, open their eyes at 14 days, are weaned at 3 weeks, and reach sexual maturity at 5-7 weeks. Average life span is 6 years.
Prevention There are two ways that one could employ to prevent house mouse infestation
  • Sanitation
    Even if the area is very small and has limited amounts of food and shelter mice can survive. Consequently, no matter how good the sanitation, most buildings in which food is stored, handled or used will have an impact on the house mice infestation if not mouse-proofed. Nonetheless good sanitation will not often eliminate mice; poor sanitation is sure to attract them and will allow them to develop drastically. Good sanitation will also reduce the adequacy of food and shelter for mice. Thus good house-keeping is of paramount importance in the endeavours of house-mouse prevention.
  • Mouse-proof construction
    One of the most profitable ways of house mouse prevention is to "build them out" by eliminating all openings through which they can enter the building. All places where food is stored, processed or used should be made mouse-proof. Dried grain and meat products should be stored in glass jars, metal canisters or sealable airtight containers.

    Seal any openings larger than 6.35mmto keep mice out of the building. Steel wool mixed with sealing compound makes a good plug. Patching material needs to be smooth on the surface to prevent mice from pulling out or chewing through the patching compound. Seal cracks and openings in building foundations and openings for water pipes, vents and utilities with metal or concrete. Doors, windows and screens should be tightly fitting. It may be necessary to cover the edges with metal to prevent gnawing. Plastic sheeting or screen, wood, rubber or other chewable materials are not good for plugging holes used by mice.
  • Traps
    Trapping is an effective control method for mus musculus. It is the most preferred control method if there are few rats in the building. Trapping has several advantages: (1) Trapping is the most safe control method compared to hazardous chemicals used to control house mouse, (2) it permits the user to make sure that the mouse has been killed and (3) it allows for disposal of the mouse dead body, It prevents the presents of offensive smell that occur if chemicals are used in the building.
    The simple, cost effective wood-based snap trap is more efficient. Bait traps with peanut butter, chocolate candy, dried fruit or a small piece of bacon tied securely to the trigger. Set them so that the trigger is sensitive and will spring easily. Set traps close to walls, behind objects, in dark corners and in places where one can easily trace mouse. Traps are placed so that mice will pass directly over the triggers as they follow the natural course of travel, usually close to a wall. Traps can be set on ledges or on top of pallets of stored materials if mice are active in such locations. Use enough traps to eliminate the rodents quickly. (Using too few traps is a common error by individuals attempting to control mice.) Mice not often travel far from their shelter and food supply, so traps are placed no more than 10 feet apart in areas where mice are active. Leaving traps unset until the bait has been taken at least once (pre-baiting) often makes trapping to be succinctly done. Glue boards are used as an alternative, which catch and hold mice attempting to cross them. Glue boards are placed along walls where mice travel. Two or three glue boards placed side-by-side will be more effective than individual boards. Do not use them where children, pets. Glue boards should be placed in places that are dust free. Glue traps should be used under moderate temperatures.
  • Poison baits (Rodenticides)
    Rodenticides are one of the most effective methods of controlling house mouse (mus musculus). Purchasing unlabelled rodenticides from the street vendors should be avoided. Rodenticides are a last resort because they endanger human health, thus trapping is advocated. Since these baits are poisonous, it is ones responsibility to ensure that these chemicals are registered. When fumigation is going to be conducted, one should make sure that it is done by a registered person or organization and check for credentials.

    Fresh bait should be place continuously since the house mouse might take about a week to die. Bait should be placed in hidden places so as to prevent bait shy.


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