Your office has been taken over by an army of mutant rats

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Lockdowns are lifting and people are starting to think about returning to the office. There is just one problem: rats have taken over.
The British Pest Control Association (BPCA) says there was a marked increase in rat activity in British cities over the course of the first coronavirus lockdown, with members reporting a 51 per cent increase in sightings during last April alone. That rose to 78 per cent by October 2020, when the cold winter months gave rats exactly the prompt they needed to start head indoors. Empty office blocks, which offered the perfect mix of warmth and – in the absence of staff – silence, have proved decidedly attractive.


“Rats will nest anywhere that’s safe from predators and sheltered from the weather,” says Natalie Bungay, technical and compliance manager at the BPCA. “That might be sewer systems, under floorboards or in wall cavities, or maybe even in stuff that’s been piled up in a corner for months and not used. If no one has been there to keep an eye on them, the rats will have been making themselves comfortable.”
In the initial wave of working from home, swathes of rats migrated to residential areas in search of food. Paul Blackhurst, head of technical academy at Rentokil Pest Control, says rats will “take advantage of any situation where there’s an abundance of food”. That meant they followed workers home during last summer to feast in domestic rather than commercial bins and pilfer the food left in gardens by budding ornithologists.
But urban centres remain their key stomping ground. According to Leeds-headquartered pest-control business, Birmingham is the most infested of UK cities followed by Newcastle, Leeds, Liverpool and London. And while the closure of pubs and restaurants has removed their usual source of food, rats, like humans, have adapted over the past year.
“Rats are having a whale of a time at the moment [because] they have stayed in offices and have been left undisturbed,” says director Jonathan Ratcliffe. “Rats, if they’re given a takeaway will love it, but if push comes to shove a cable will do. They’ll eat wood, carpet, plastics. Leave them alone and they’ll cause a nightmare – they’ll eat everything.”


As if that wasn’t bad enough, some of the rats that have been running over keyboards and making themselves at home in desk drawers are mutants whose breeding has made them impossible to exterminate by traditional means.
“The main genetic mutation we’re concerned about is the one that causes them to be resistant to our poisons – that can be passed from the mother, father or both,” says Blackhurst. There is resistance to not just the poison that exterminators were using in the early part of the 20th century, but also to the second-generation ones that have been used more recently. “This has been going on for quite a while, but there’s not enough data in the UK to say which areas have this mutation,” Blackhurst adds.
There may not be data to show exactly where poison-immune rats exist, but in a recent study from the Campaign for Responsible Rodenticide Use, 74 per cent of the rats analysed carried a rodenticide-resistant gene. That’s a problem for employers, who could open up their offices to discover a rat infestation. Ratcliffe says the usual way to get rid of rats is to identify where their rat run is, lay bait and, when they have succumbed, remove their bodies. If genetic mutations prevent them from succumbing another solution has to be found.
Rentokil believes it has found that solution: a “rodent burglar alarm” called PestConnect. The system – which has identified that rats are most active in UK commercial premises at 12.24am – uses a number of devices connected through the Internet of Things to monitor rodent activity, activate a range of humane traps and alert a pest controller when a caught rat needs to be disposed of.


Supermarket chain Tesco uses the system across its network of warehouses and stores. The supermarket’s pest control head Tony O’Donovan says it has enabled the organisation to reduce the amount of poisons it uses by 40 per cent, something that fits with its overall commitment to “tackling the global climate change threat, protecting important ecosystems such as forests and marine environments, and advocating for sustainable agricultural practices that protect soil health and biodiversity”.
Even with technology to help identify the source of the problem, a rodent infestation is never going to be easy to deal with, particularly in a modern office block. Knowing where rats are getting in and exterminating them when they do is one thing; sealing entry holes that are hidden under floor boards or concealed by cavity walls is another entirely.
“The bigger the building the more complicated it is to deal with because you need to find the root-cause of the problem,” says Bungay. “If you’ve got a building with 10 floors and offices on each floor it will take time and money to solve. You have to figure out where the rats are coming from. You have to monitor and pinpoint where they are coming in – it could be a fault in the sewer system – then you have to fix that or you will have a constant feed of them.”
The good news for anyone working in a shiny new office complex is that, even with next to no humans going in over the past few months, rats are unlikely to have moved in en masse. As a species that is naturally suspicious of humans, the sounds and smells of facilities managers turning on lights, sending in cleaners and keeping the air-conditioning going will have been enough to hold them at bay.
Employers who rent lower grade space that has less money spent on its upkeep are likely to have a problem, not least because rats who have been left to their own devices will have been using those offices as a breeding ground. And, with a rat’s gestation period lasting just 21 days, that can mean only one thing: potentially huge numbers of rodents waiting to ruin the office reopening.
“A lot of workplaces have been left empty for a year, but rats breed a lot if they’re left unchecked,” Ratcliffe says. “They can have six litters a year and up to 12 pups in each litter.” Given that prospect, the advice from all pest controllers is clear: any employer planning on welcoming staff back soon should sweep their offices for evidence of rodent life first. They could be in for a nasty surprise but, after a year of Covid chaos, the last thing organisations need at this stage is an outbreak of rat-borne illnesses like salmonella among their ranks.
“The worst problem is that employers have an infestation that they don’t know about; that people come back to the office and start leaving foodstuffs about and then at night it’s like crazy times for the rats,” Ratcliffe says. “We’re expecting more calls on the back of that. The rats are either close or in the buildings already.”
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