Lessons from America’s first ‘war on rats’ summit

On Pier 57 on New York’s Hudson riverfront, in a room tucked behind bustling food stalls, experts from across North America gathered last month to discuss a topic unpalatable to the lunchtime diners — and still less to the nearby residents of Chelsea. 

“I’m excited to welcome my fellow generals in the ‘war on rats’ to our great city for the inaugural National Urban Rat Summit,” said New York City mayor Eric Adams, who has declared Rattus norvegicus “public enemy number one”. For two days they shared scientific insights and practical experiences in tackling a pest that causes widespread anxiety among city dwellers. 

If you are buying, you really do need to get a good inspector. If I was a renter, I’d make sure to know who is responsible for pest management

Infestations, and their influence on where people choose to live, have become a focus area for a number of property agents across US cities. StreetEasy, a New York rental and purchase site that’s a subsidiary of Zillow, has multiple blogs and discussion threads seeking or offering advice and warnings. RentHop, a property rental website, conducts periodic surveys “to help renters and homeowners understand the levels of rodent activity in their area, helping them decide where to live.”

The latter shows rodent-related calls to 311, a US non-emergency number for government services, were highest in Chicago (nearly 43,000 calls were logged in 2022), ahead of New York City (more than 35,000), Washington DC (11,000) and Boston (3,500). “It’s a big problem, not just in the subway but in people’s homes,” says RentHop analyst Shane Lee (whose own house in Brooklyn was infested). “Most people care about it.” Callout data from pest control company Orkin also suggests Chicago has the greatest problem.

The National Urban Rat Summit is part of the Adams’ administration’s sustained rat action plan: mitigation zones with focused inspections in areas of greatest concentration, stepped-up waste collection, the appointment of a “rat tsar” to co-ordinate the response, and the launch of “rat academies” to train residents A rat information portal offers detailed maps showing health department inspections.  

But the summit’s nationwide invite list suggests a new tactic to pool knowledge and step up co-operation. “We all have rats, and every city takes a different approach,” says Leah Helms, supervisor of Seattle’s Solid Waste, Rodent, and Zoonotic Disease Program, who welcomed the summit. “Nothing like this has happened before.”

The problem of rats is not new. New York’s Board of Health first imposed requirements (and fines) for owner-occupiers and landlords to take responsibility for control measures in the 1960s, when the city’s infrastructure crumbled, leaving many empty or demolished lots, and mayor John Lindsay abandoned metal garbage bins in favour of plastic bags on the streets. 

But more recently, climate change has exacerbated the problem, says Jonathan Richardson, assistant professor of biology at the University of Richmond in Virginia. Gerard Brown, programme manager for the Rodent and Vector Control Division in Washington DC adds that “the pandemic changed everything”. Lockdowns and working from home has resulted in a surge in food home delivery, resulting in bins overflowing with unwashed containers. “Rats don’t discriminate, they can show up anywhere,” he says. “Our focus is on changing human behaviour by educating people.”

Most New Yorkers have rat stories, spotting them in the streets but also in buildings, coming up from their toilets or in their beds. Seattle even produced a handy, multilingual comic on what to do if a rat comes up your toilet (including close the lid and flush, then squirt some dishwasher liquid). A 2015 video of “pizza rat” dragging a slice down the steps of a subway went viral. 

Scientists at the summit highlighted the burden of the emotional stress of rodents as much as the direct (and often overblown) concerns over disease. A recent rise in cases of leptospirosis, a bacterial infection transmitted in rat urine, has caused concern; there were two dozen incidents last year.

Other speakers emphasised that incidence is higher in areas of greatest poverty and inequality, where landlords often fail to control infestations and residents have few options to move. Crowded apartment buildings often have more problems than single family houses. 

But the data remains incomplete. In the absence of systematic surveys, rat sightings registered on sites such as New York’s rat information portal are based on residents — typically tenants — who bother to call 311. A glaring gap is left by homeowners who go directly to private pest control companies and don’t alert the authorities.

There are scant rigorous studies as to effective mitigation. Brown placed more emphasis on improved sanitation, including more regular garbage collection, the use of sealed metal-lined bins and support for elderly residents unable to lift trash cans. “Rats are smart, they chew through the plastic bin[liners] like a piece of cake,” he says. Another approach discussed has been the use of rat contraceptives. But many experts at the summit, including Richardson, expressed scepticism in the absence of rigorous trials. Brown stressed that rats need to eat them consistently over time and “if you have choice, would you rather eat a contraceptive gel or chicken?”

But one revelation for him at the Summit was genetic tracing of rats and the infections they carry, which show rodents themselves are home lovers who rarely move far. “The vast majority of rats move very little during their lives — basically between their burrow or nest and their food resources,” says Jonathan Richardson, a researcher at the University of Richmond in Virginia. “A rat moving more than 50 – 100 metres is rare.” As a result, they may not necessarily move on if elimination methods are put in place.

Richardson said that few cities in the world have rid themselves of rats, although greater municipal efforts around sanitation and stronger societal importance placed on hygiene means they are less prominent in cities such as Tokyo, Barcelona and Amsterdam. He also expressed caution about the overuse of rat poison, which enters the food chain, contributing to deaths of hawks and owls — including Central Park’s much-loved Eurasian eagle-owl, Flaco — and has even been found in fish. 

Instead, Claudia Riegel, director of New Orleans Mosquito, Termite and Rodent Control Board, advised researching habits and knowing what to look for: “burrows, bait stations, droppings. If you are buying, you really do need to take the time and get a good inspector. If I was a renter, I’d make sure to know who is responsible for pest management.”

Despite the summit’s efforts to step up a response, most experts there seemed to believe city dwellers will have to learn to live with rats. Chelsea Himsworth, deputy chief veterinarian for Canada’s province of British Columbia, and a rodent expert, warns that the “war on rats” will not succeed because it is such a complex “wicked problem”.

City mayors often step up their campaigns against rodents as a way to shore up support on a non-partisan issue. But New York’s rats are certainly likely to outlive Adams, recently charged with fraud and bribery, who may not even serve out his full term as mayor.

Andrew Jack is the FT’s global education editor

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