The word rodent originates from the French word, rodere, which means “to gnaw.” All rodents have a large, strong set of rootless incisors at the front parts of their jaws. They use their sharp incisors to gnaw food, excavate burrows, and defend themselves. Rodents make up about forty percent of all mammal species. They live in every continent apart from Antarctica because it is too cold there. Most rodents are small animals with robust bodies, short limbs, and long tails. Common rodents include rats, mice, squirrel, hamsters, gerbils, chinchillas and guinea pigs.
Rodents are social animals, they are nocturnal and good climbers, especially for Rattus rattus. Their range of movement is 30-50m for rats and 5-10 m for mice. They swim very well and can dive. Rats take 15-30 gm food and consume about 30 gm water daily; mouse takes only 3 gm of food and little amount of water every day. These animals contaminate more food than they eat with their faeces, urine and hair. Rats reproduce 5-8 litters per year and mouse make 5-14 per litter. Their average life span is 1 year.
Rodents infest our homes looking for the same comforts that we do — food, shelter, warmth, mate, breeding space and water.
While they are at it, they cause destruction of wood, fabric, paper, bags, food, and also transmit diseases through the ectoparasites of rat like fleas, ticks and mites, by food or water contaminated by rodent faeces, direct contact with rodent faeces, as well as by rat bite.
DISEASES CAUSED BY RODENTS
a. According to the Centre for Disease Control, “more than ten million people have fallen ill, with a good number of them dying, from rodent-borne diseases in the past century alone”. Rodents are therefore of great public health importance as they are carriers of viral, rickettsial and bacterial diseases. They cause diseases such Urban typhus, Scrub typhus, Scrub plague, rickettsia disease, Spotted fever, Hantavirus infection, Rat bite fever like Lassa fever plague, leptospirosis, murine typhus and so on.
RODENT CONTROL MEASURES
To control rodents, three measures are usually considered: sanitation, exclusion and preventive measures.
a. Sanitation involves the hygienic disposal of wastes. It is a very effective method of rodent control as it deprives rodents of food and shelter thus reducing their population.
Sanitation measures include:
Storing bulk food items like rice, beans and cereal in large metal containers or other airtight containers with tight fitting lids, rather than bags or boxes that can easily be gnawed through.
Cleaning food and beverage containers before discarding or recycling.
Ensuring stove tops are clean and free of food scraps.
Entry points around cabinets, interior walls, attic, and crawl spaces should be sealed with steel wool, caulk or metal mesh.
Keep attic, crawl spaces, and cabinets near sinks clean and free of moisture.
Removing clutter such as paper, fabric and cardboard that mice might use to build their nests.
Keeping dog food or other pet food stored in airtight container overnight.
Keeping a tight-fitting lid on all trash cans.
Outdoor sanitation typically involves:
Keeping trees and bushes trimmed and removing trimmings from the property.
Picking up any fallen fruits or nuts from fruit trees.
Triming bottom of hedges or bushes to expose soil beneath and decrease rodent shelters.
Not planting ivy as it provides shelter and a food source for rodents, snails and slugs. Ivy on walls can provide “rat ladders” to windows, attics and other interior spaces.
Keeping compost piles as far away from structures as possible and grass cut to no more than two inches tall.
Maintaining at least a 2-foot space between bushes, shrubs, fences, and buildings. Also, removing tree limbs within 3 feet of a structure or roof.
Avoid having a bird feeder since it could be source of food for rodents.
Keeping outdoor grills and cooking areas clean.
Keeping firewood away from the ground and as far away from structures as possible to reduce rat shelter areas.
All food and water sources should be removed where possible. Pets should be feed in the morning and all uneaten food removed immediately.
Fixing any leaking pipes or drains.
Waste accumulation prevention and not piling up unwanted building materials.
Use plastic trash bins and clean them frequently. Replace cracked, loosely fitting or missing lid. Trash cans should be kept as far away from the building as possible.
b. Exclusion measures:
Exclusion includes finding and sealing up any entry points on the structure you can find. This method rodent proofs your house. Such measures include:
Inspecting the foundation all the way around the home for any gap, crack, or hole. These need to be repaired.
Inspect all utility entry points as areas where utilities enter the home can also make easy access points for rodents. Seal any gap or hole larger than a quarter of an inch around the wire, cable or pipe with copper mesh, caulk, hardware cloth and mortar, sheet metal or other suitable materials
All doors, door frames, windows and window frames should be checked. Any weather stripping that does not create a tight seal should be replaced. Also, broken window panes, damaged window or door screens should be replaced. Gaps, cracks or holes around frames that are a quarter of an inch or larger should be repaired. If gnawing damage is present on doors, a metal kick plate should be installed to prevent any additional gnawing.
c. Preventive measures help to reduce rat population by trapping and baiting them. Preventive measures also help eliminate re-infestation of rodent.
These measures include:
The use of Rat traps with baits to capture rats.
Note: rats are very skilled at avoiding rat traps.
Rat traps should be used by at least 5 percent of the population to be effective in controlling rats. Rat traps can also be home made.
The use of Rat poisons (rodenticides) such as Barium carbonate, zinc phosphide, warfarin, pindone etc.
Note: long term use of rodenticides will make the rodents develop resistance.
The use of fumigation to kill both rats and fleas. Commonly used fumigants are carbon disulphide, calcium cyanide (cyanogas), sulphurdioxide and methyl bromide. Powdered Calcium cyanide can be pumped into rat burrows using ‘cyanogas foot pumps’. The opening is then sealed.
Note: Exposure is hazardous to humans and other livestock, therefore care should be taken during fumigation.
Natural enemies of rodents such as dogs and cats that are not too domesticated can be introduced into a home to kill the rodents. Outdoors, large birds of prey including hawks, falcons and owls which feed regularly on rodents can be attracted. Many snake species also prey upon rats. This method is however hardly effective for exterminating a whole population of rodents.
ANY BENEFITS OF HAVING RODENTS
As the saying goes, there are always two sides to a coin. Even though rats pose a great danger to humans, they are important as:
Research tools: rats and mice have very similar anatomy and physiology to humans therefore, they are the preferred laboratory animals. Their behavioural patterns can be easily studied. They also have short life cycle, easy to feed and maintain. Rat models are preferred for studies in pharmacology, neurobiology, nutrition, cardiology, immunology, toxicology, physiology, behaviour and other science areas.
Rodents are a considerable source of animal protein and income for many villagers in Africa and Asia. Infact, the Adi tribe of an Indian village have a yearly festival on 7th March that is celebrated with a rat cuisine called bule-bulak oying. This delicacy is prepared with rat’s intestines, liver, stomach, testis, fetuses, tails, legs boiled with salt, chilli and ginger. Also, in many villages in Nigeria, the African giant rat is a favourite of many families.
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