Rats are one of the most problematic pests at the best of times for businesses handling food and homes in urban areas where any source of food is nearby. Now, during this COVID-19 global pandemic, even rats are under pressure.
Throughout urban areas, there are populations of rats that have relied on ready sources of supplies from the many businesses handling food or where food is eaten and discarded. Food waste is generated not just in restaurants, cafés and fast-food outlets, but also in offices and other businesses where employees take their own food into the buildings.
Normally, rats live close to their food sources. With the widespread lockdown and closures of businesses, however, many of these regular sources of food have disappeared. Urban rats are now facing hunger in their own territories, which drives them to change their normal behaviour; they are no longer nocturnal and wary of people or new surroundings. They become bold and venture out to new places. This behaviour threatens our food supplies at any point along the supply chain as large numbers of rats try to access new areas for shelter and food.
The risk from rats #1: Population growth
Rats are fast breeders when food is plentiful and there is little predation. In urban areas, even the presence of cats and dogs has little effect on numbers and, in some cases, may even result in more food being available.
Brown rats have litters of 7-8 pups and can have from 3-6 litters per year. The pups take 2–3 months to reach sexual maturity, at which point, the females from this first litter can mate and, within 21 days, produce 7–8 pups each and they also go on to have 3–6 litters per year. With a food supply and lack of pest control, a rat population can increase exponentially in a new area.
Rats are highly adaptable to their surroundings and the availability of food, water and shelter. An urban environment generally offers an abundance of these both indoors and outdoors. Their agility, curiosity and intelligence means they’re very adept at finding new places suitable for their survival.
Finding a new area triggers a rapid growth in population until factors become limiting. The same effect occurs when control strategies are not sufficient to wipe out a population. Rats can quickly restore their numbers with successful breeding until competition for resources limits breeding and survival.
The risk from rats #2: Spread diseases and parasites
Rats can spread a wide range of diseases and parasites into the places they infest in urban areas. A single rat can also carry multiple types of pathogen and parasite, including bacteria, viruses protozoans, and parasitic worms. Rats also carry ectoparasites that include fleas, ticks, lice and mites, which are vectors of other diseases. They contaminate their runs and the places they visit with urine, faeces and saliva, which can transmit diseases. These include:
- Leptospirosis and Weil’s disease:
- Rat-bite fever
- Rat tapeworm
There are many ways that we can catch a disease from rodents either indirectly in the places they have infested or directly from coming into close contact with them.
- Drinking contaminated water or eating contaminated food.
- Inhalation or direct contact with rodent excreta (urine, faeces, saliva) on contaminated surfaces.
- Handling or inhaling microorganism-containing particles aerosolised from hay, woodpiles or other materials contaminated with infectious rodent urine.
- Particles in dust made airborne by sweeping places where rats are present.
- Handling of infected rodents.
- Bites and scratches — microorganisms carried in saliva can infect both humans and other rodents.
- Dogs and cats eating rodents and then catching parasites such as tapeworms that can be passed on to humans by them.
- Rodents can also act as reservoirs for various flying-insect-borne diseases.
During the pandemic, health services are under immense pressure from the massive influx of patients infected with COVID-19. They are focussing a large proportion of their resources to managing these patients and have reduced capacity to deal with other diseases. Rat infestations create multiple threats to health, therefore it is vital to maintain measures to control them to both protect food supplies and prevent overloading of the health services.
The risk from rats #3: Damage to products and property
Rats cause damage to property from their tendency to burrow and their ability to gnaw many materials to gain access to places or out of habit. Rat’s teeth are hard enough to gnaw wood, aluminium, plastic, lead and even some types of steel — gnaw marks are often the first sign of an infestation.
A survey by the Centre for Economics and Business Research (Cebr), commissioned by Rentokil, found that rats were the most destructive pest for businesses. They cause gnawing damage to buildings and fixtures, making holes to gain access around doors, windows, pipework, drains – they can even swim round toilet U-bends!
The most common problem reported by businesses was damage to electrical equipment, with 49% reporting machinery or wiring as most affected. This can result in production downtime or fires when rats gnaw through the plastic insulation and short the wires.
The risk from rats #4: Consume and contaminate food supplies
Rats need to eat about a tenth of their body weight each day and have daily access to water. They nest near their food supplies and make multiple visits to their food sources. They contaminate the food and surrounding surfaces with urine, droppings, and filth picked up from the environment. Whatever they gnaw will also be contaminated with their saliva.
Rats are capable of gnawing through many types of food packaging, including cardboard, paper, plastic, and multilayer packaging materials. This causes loss of stock to businesses both from the food rats eat and contaminate or leave in damaged packaging.
The economic cost of rats
Rats are a financial and business risk and pose a risk to public health and food security. Infestations result is several costs:
- treatment to eradicate rats
- repairs to property
- replacement of contaminated stock or defaced items
- loss of reputation for towns, cities and businesses
- loss of business
- potential litigation
Pest control services perform a vital function to prevent the populations of rats in urban areas growing out of control during lockdowns and concentration of food supplies in the retail supply chain. With health services already overloaded from dealing with coronavirus patients, it’s essential to take measures to prevent other sources of illness.