Rats and mice are a serious threat to our health and property. Like all pests, they live in constant search of food and water. Rats are omnivorous and will eat any food that is available in the home and work environment – even protein-based foods such as meat, poultry, eggs and fish. Mice are herbivores, preferring cereals, grains, fruit and vegetables. Both species readily invade our living spaces if they find easy access to food and water. Having set up home within the safety of our houses and offices, rats and mice will breed prolifically and within a few months will multiply into the hundreds. However, both rats and mice leave plenty of evidence that alert us to their presence.

Most noticeable of these are their dark brown droppings; you can tell the difference between a rat and mouse dropping from the size – about 2 cm long for rats, and 0.5 cm long for mice. In fact, rodent droppings are likely to be your first indication of a possible infestation. Scratching sounds in soffits and furniture recesses can become audible when the environment is quiet and, if you share your home with cats or dogs, they will quickly alert you to a possible presence. In Malta, we have three types of rodents: the Norway Rat (Rattus Norvegicus or Far xxxxx), the Black Rat (Rattus Rattus or Far xxxxxx), and the Domestic Mouse (Mus Musculus or Gurdien xxxxxxx).

The greyish-brown Norway Rat is more appropriately known as the sewer rat because it favours the sanctuary of our sewers where it has no natural predators; they are particularly strong swimmers and can swim up rain water gutters and even against strong currents in sewer canals. Their filthy environment means that they carry dangerous and potentially fatal bacteria on their feet and body hair. In fact, passageways that are regularly used by the Norway Rat gradually build up a greasy layer of scum from their bodies. As they rummage through our food supplies and scuttle over surfaces, they leave this imperceptible trail of filth which we inadvertently touch and carry to our mouth. Although the Black Rat and Mouse live in relatively cleaner environments, their presence in our homes can be equally dangerous to our health.

All three rodent species shed thousands of hairs from their body; they continuously urinate and drop faeces onto our food stores and belongings. Accidental ingestion of food and water containing their body hair or waste is dangerous and potentially fatal. Some of the diseases and bacteria include Leptospirosis (Weil's disease) which they also transmit through contamination of water with their urine, as well as salmonella, e-coli, listeria, tuberculosis, brucellosis, and rat-bite fever. The fleas, mites and ticks that they carry on their bodies are equally dangerous and can transmit disease to our pets as well. But rats and mice don’t only bring with them the risk of contamination; they are also a major cause of serious financial loss – both in the home and work environment.

Rats and mice have strong sharp teeth that grow very quickly. To keep them trimmed back, they continuously gnaw on hard objects such as wood, plastic, and poorly treated concrete. One of their favourite objects to grind is electrical cabling. At best, a rodent will short-circuit your electrics and cause power failure or outage; at worst, they will cause electrical fires that ravage your home or work place.

Insurance companies in many countries have now introduced a policy of no-payment if it can be proved that electrical fires were caused by a known infestation of rodents that was ignored.

In Malta, a favourite DIY product for rodents is rat poison. But laying down poison in your home or work space can have serious consequences if you, your children, pets, or employees accidentally ingest it, or absorb it through smell or touch. Even if no accident occurs, a poisoned rodent will crawl away to die in a secluded area; these areas are often inaccessible to us, and rotting rat carcasses can create hazardous conditions for disease as well as produce noxious odours that are difficult to get rid of. There is also the impact on the environment and danger to wildlife since poisoned rodents could contaminate fresh water supplies which poison wildlife.

Rodent traps are another favourite, but handling live trapped rodents leaves you vulnerable to contamination and bites, while dead rodents harbour fleas that can cause organ failure if they bite you. Other modern contraptions include ultrasound repellers that emit sounds which humans cannot hear but which are uncomfortable for rodents. Although effective in the short-term, these solutions are largely ineffective since rodents will quickly acclimatise to the sound.

There are many preventive measures that you can take to mitigate infestation (see box), but because rodents breed so prolifically, it is very difficult to control a population explosion simply by killing a couple of rats or mice. For the well-being of your family or employees, you should contact a professional pest control company that has been licensed to operate the right equipment for extermination of rodent infestations. These companies are equipped with the knowledge to track down the source of infestation, and can provide the equipment needed to rid your environment of rats and mice safely and humanely. Professional handling of the extermination process also means that your pest control company will rid your living or work spaces of dangerous rodent carcasses.

What can you do

• Cover your rain water gullies with mesh and seal up sewer slabs so that the Norway Rat will find no openings above-ground.
• Avoid storing boxes containing paper, clothing, or wool in the basement as these provide excellent nesting for the Black Rat and Domestic Mouse.
• Sweep the kitchen floor regularly, particularly for breadcrumbs, and wipe down all food surfaces and appliances. Make sure that your garbage cans have well-fitting and secure lids.
• Don’t leave pet food out overnight and sweep up spilt birdseed from around your birdcages. Regularly clean out aviaries and animal pens. Seal up your pet foods in plastic containers – rats and mice will rip through packaging in no time at all. If you need to stockpile animal feed, move it around regularly: rodents are extremely wary of change and will wait before trying out the food source.
• Seal up all cereals or grains in plastic or glass containers and refrigerate tubers such as potatoes and carrots.
• If you have fruit trees in your garden, collect the windfalls regularly. Do not put leftover meat, poultry, fish, animal and fish bones, or dairy products in the compost bin and make sure that you regularly turn over your compost and lime it properly.
• Plant bushes away from the walls of your house. Creepers may look beautiful, but they provide Black Rats with very easy access to your house. If you have trees close to your house, prune them back regularly and make sure that your air vents are sealed up.
• Repair all plumbing leaks to prevent easy access to good water. When not in use, cover up fresh water pools and outdoor jacuzzis.