Three months ago, rice farmer William Lebango put his three-year-old son, Stuart, to bed and sat eating supper on the porch of the small mud-brick home in central Tanzania he shares with his wife and three children.

Suddenly, from inside, they heard a blood-curdling scream. While Stuart was asleep, a rat had climbed inside his mosquito net and bitten his leg.

‘We ran in and searched for the rat and found it hiding in his bed,’ Lebango recalls, cradling his son and showing his scar from the rat bite. ‘But it escaped before I could kill it.’

Over the ensuing months rats have continued to plague his family. On the almost daily event that Stuart sees one of the rodents scurrying through their house, he runs away in terror and hides, calling for his father to save him.

Lebango’s other sons, aged 16 and 12, have so far escaped being bitten but his wife, Zwena, has been diagnosed with typhus (a rodent-borne disease which if left untreated can have a mortality rate of 60 per cent) while others in the family have been wracked with various mystery fevers suspected to be associated with the rats.

‘It makes me so angry because it never ends,’ Lebango says. ‘Nothing can stop the rats.’

Nightmarish stories like this abound in the remote villages on the border of Tanzania’s Udzungwa Mountains National Park, where Stuart and his family live. And they have equally terrifying implications for us all.

As demonstrated in recent years by the Ebola epidemic of 2014 and Covid-19 (both of which are believed to have originated from bats, although the latter has yet to be fully proven) an unknown pathogen can all too easily spill over from an animal to a human host and mushroom across the world.

As one pandemic recedes from view, it is feared the next may already be brewing in rats. And to compound matters, it appears to be boom-time for the rats in question.

While rodent-borne diseases are far more of a problem in the developing world due to poor-quality housing and sanitation, rats are also proliferating in the wealthiest countries.

Any population counts are hard to come by, but anecdotally there has been a particular increase during the Covid pandemic as deprived of their usual food sources in empty city centres, rats have been forced to expand their territories, coming into greater contact with people.

In Glasgow, striking refuse workers recently warned of a ‘modern-day plague’ while in New York rat sightings have rocketed to more than 21,000 over the past year (compared to 15,000 in 2019).

The Parisian authorities have embarked on a policy of dératisation to cope with the city’s worst infestation in several decades, even dynamiting burrows in municipal parks in an attempt to bring its population under control.

A few months ago in London – where the rat population has been estimated as high as two rodents for every person (although scientists baulk at such surveys saying the true number is impossible to judge) – a pair of rats were filmed nibbling on freshly-baked croissants on the bakery counter of a Sainsbury’s branch in Islington.

It would be hard to create a more effective harbinger of pestilence than the rat: muscular, ferocious, boasting incisors that can chew through metal and concrete and capable of squeezing through the tiniest of gaps to access food sources in our homes.

According to the World Health Organization, rats are already responsible for causing more than 400m infections in people each year spread through bites, the fleas they transport, urine and aerosols.

Across various species of rats there are more than 60 pathogens which can infect humans – including haemorrhagic fevers, coronaviruses, hantaviruses and arenaviruses – alongside hundreds of unknown pathogens.

Rats are the vector for lassa fever, an ebola-like acute viral illness which infects up to 300,000 people in West Africa each year causing around 5,000 deaths. Their fleas are also responsible for regular outbreaks of bubonic plague in numerous countries across the world.

The worst-affected is Madagascar where the disease is endemic and where there is increasing evidence of antibiotic resistant strains.

The last large plague outbreak there five years ago turned into the one scientists really dread: so-called pneumonic plague where the disease spreads via human to human. After reaching the capital city it eventually burned out, but not before killing at least 209 people.

While we have all but eradicated plague as a disease from the developing world due to improved sanitation and minimising our contact with rodents, a few years ago scientists at Cornell and Columbia University investigating the presence of fleas on New York rats made a worrying discovery.

Among the 6,500 specimens collected were around 500 Oriental rat fleas, notorious for their role in transmitting the Black Death which killed as much as 60 per cent of Europe’s population in the 14th century. All that was missing was the pathogen itself.

The study also discovered the rats teeming with 18 novel viruses. ‘Rats are sentinels for human disease,’ said Dr W.Ian Lipkin, the director of Columbia’s Centre for Infection and Immunity and one of the world’s leading virus hunters, at the time of the study.

‘Everywhere they go, they collect microbes and amplify them. And because these animals live close to people, there is ample opportunity for exchange.’

Professor Steve Belmain, Britain’s foremost expert on rats, has similar concerns about an animal he has studied up close over the past three decades. Now he is leading a UK-funded initiative to take the war to rats.

The project – the first of its kind in the world – is launching in Tanzania and Madagascar and aims not just to drive the rats from people’s homes but out of their villages all together through a community-wide systematic cull.

If successfully proven to drive down rates of disease, the hope is that the project can transform methods of rat control in the developing world before the next ‘Disease X’ is given time to spread. ‘We need to get a grip on this to stop the next pandemic coming to the UK from somewhere else,’ Prof Belmain warns.

The 54-year-old Belmain, who works at the Natural Resources Institute at Greenwich University, has made his name trapping rats all over the world. Recently he was awarded the prestigious Queen’s Anniversary prize for his work and invited to Buckingham Palace where he hobnobbed with Prince Charles about the rat problems he too suffers on his Highgrove Estate.

Indeed the Royal family has long sought recourse from rats, often employing their own personal catchers. Princess Amelia, the daughter of King George III, had a rat catcher called Robert Smith who in the 18th century published his personal guide to the ‘utter extirpation of those mischievious vermin’.

Queen Victoria employed a celebrated trapper called Jack Black, who was something of a minor celebrity in 19th century London for his green coat, white leather trousers with a rat-belt buckle and party trick of sticking a hand into a cage full of wild rats without getting bitten (although his hands were reportedly pock-marked with scars).

Like his Victorian predecessor, Professor Belmain has endured his fair share of bites but still remains in awe of his subject and delights in near-constant rat chat: from their extraordinary physiology to skewering urban myths.

He dismisses the old adage you are always within six feet of a rat, and also the story told in cities all over the world of the fabled ‘King Rat’ whereby so many rodents cluster together that their tails entwine and become one seething mass.

However, he insists stories of rats clambering up sewage pipes while people are sitting on the toilet are, I’m afraid to report, true.

Of course the most famous rat story of all is the Pied Piper of Hamelin. Belmain, who is married to a German wife, says this too is most probably a myth. The way he tells it, the children supposedly snatched by the piper in lieu of payment for ridding the town of rats were more likely to have been lured away as part of agricultural resettlement schemes in the 13th century to populate Eastern Germany.

Despite the obvious comparison to his own project, he is quick to dismiss any notion of himself as a modern day pied piper, even if striding through Tanzanian villages in a wide-brimmed bush hat and waterproof trench coat while pointing out rat burrows he does look the part.

The plague rat invasion which threatens the next pandemic

‘I don’t think eradication is a word we should be using,’ he says. ‘It’s about sustainable management.’

Belmain and his team have identified two clusters of 12 rural villages in Tanzania and Madagascar to take part. In each country, six of those villages are being provided with 5,000 rat traps in an attempt to fully purge them of rodents while the other six are being left as a control.

Those being given the traps are being told to use them in perpetuity. ‘We are telling people the rats will come back again,’ Belmain warns. ‘Trapping now becomes your future.’

A hundred or so surviving rats will be fitted with Bluetooth collars (costing several hundred pounds a piece) to monitor their movements in a project led by Dr Sandra Telfer, a senior research fellow based at Aberdeen University. Rats will also be tested for various diseases to explore the impact of the reduction in their population.

Simple as it sounds, the project is not without risk. As described at the beginning of Albert Camus’s The Plague, numerous outbreaks have started with a mass die-off of rats forcing their infected fleas to seek out new human hosts on which to feed.

In Madagascar, the 12 selected villages involved in the project are in the country’s plague zone (albeit a less-affected part).

Belmain says they will be taking precautions such as covering traps in flea powder and setting up flea traps (basins of water with floating candles) to monitor any prevalence of disease. ‘What we are recommending really goes against established protocols,’ he admits.

In Tanzania, the researchers are particularly focused on leptospirosis, a bacteria which spreads through rat urine and is estimated to cause around 1m cases and 60,000 deaths a year (a figure thought to be a major underestimate as it is often misdiagnosed as malaria).

According to Prof Belmain, the most lethal strains can have a mortality rate of around 40 per cent. While most severe in the developing world, in the UK there are around 50 cases of what is also known as Weil’s disease a year.

The rat trappers have largely been welcomed with open arms – unsurprisingly so, given the daily difficulties caused by their prey.

Throughout the villages rats bite children, attack breast-feeding mothers, scamper across people in their sleep, shred school uniforms to line their nests, steal food and devastate harvests in the field. The collective noun a ‘mischief of rats’, hardly does it justice.

In her growing desperation to solve the problem, Pelagia Mbunzi, who lives in one of the villages involved in the project called Ichondwe, has recently decided to buy a cat (a rarity in rural Africa where the animals are often associated with witchcraft).

In 2020, the 60-year-old was bitten by a rat when she was asleep and woke up to find the sheets stained with blood. The wound ended up getting badly infected and she also suffered a serious bout of rat bite fever. Fortunately she was able to source antibiotics in time; it is not uncommon for victims to lose limbs which turn gangrenous.

Mbunzi, a rice farmer and mother-of-five, lives alone. Her children are all in the Tanzania capital Dar es Salaam, a day’s drive away. For the past two years her husband has been an in-patient at a local hospital 40kms away, where he is treated for epilepsy and a host of other health problems.

While her cat, Puss, provides much-needed company, it is terrible at catching rats. Every night they run riot, vaulting across the ceiling rafters and spraying her mosquito net with urine.

‘They are my enemies,’ she says quietly of her unwanted house guests. ‘It would need the blessing of God to get rid of all these rats. If they disappear from my house and the village it will be a miracle.’

These house rats are rattus, the species which carried plague across Europe during the Middle Ages and are commonly known as the black rat (although in Africa have adapted to their environment sprouting distinctly brown fur).

The rats are thought to have arrived in Tanzania around the 14th century on board the dhows of Arab traders crossing the Indian Ocean. In Britain, black rats have in recent centuries been nearly entirely expunged by their far larger cousins, the Norwegian rat (another invasive species which confusingly given its name is thought to have originated in China).

Worldwide there are in excess of species of 2,000 rodents – nearly half of all mammals on earth – characterised by their sharp and permanently growing pairs of incisor teeth. But brown and black rats are by far the species most adept at exploiting us for their needs.

As the human race has expanded, gobbling up wilderness into farmland and urbanising into sprawling super cities, we have in turn created ideal conditions for rats to thrive.

While Professor Belmain’s project is focusing on rural areas and villages that border large agricultural landscapes teeming with rats, there is particular concern about the proximity with which people and rodents are living alongside one another in urban shanty towns.

In the city of Morogoro, where the Tanzania researchers he is working with on the project are based at Sokoine University, rats bring misery to residents in its poorest neighbourhoods. Abdul Juma Haridi, 58, a father-of-three who lives in the sprawling Chamwino shanty town, was bitten by a rat on his foot while sleeping 10 years ago and the wound became gangrenous leading to four toes being amputated.

Haridi, who previously worked as a plumber, has been reduced to selling fruit and vegetables on the floor outside his house and is now entirely dependent on his wife, Sauda. ‘I’m always in pain,’ he tells me.

Professor Rhodes Makundi, a rodent researcher based at Sokoine University who is also involved in the project, says in recent years his scientists have discovered several new Lassa fever-like diseases among rats (including the Gairo and Morogoro virus).

They have also discovered the bacteria which causes leptovirus is present in up to 30 per cent of some species of rodents.

‘I could see a point where if you are not careful some of these haemorrhagic diseases come into humans,’ he says. ‘An outbreak could be very serious... by the time we get it under control many people would be infected and probably would also have died.’

If proven successful, Professor Belmain hopes their project could be expanded across the developing world.

He says it would be too difficult to bring such mass community trapping into force across Europe due to the prohibitive cost of labour, but where he does see it making a difference is on livestock farms which are often plagued by humungous brown rats grown fat on animal feed.

He is currently involved in a separate Europe-wide project trapping rats on British farms across Kent, Essex and Norfolk to assess the diseases they are carrying. The largest rat he has caught weighed 700g and measured about 60cm snout to tail.

These brown rats are so huge they often shrug off the traditional snap traps.

Currently farmers rely on the blood-thinning poisons known as anti-coagulants to control populations although there are increasing calls for these to be banned due to the wider environmental damage they pose – especially through so-called secondary poisoning when the animals that predate on rats such as barn owls ingest the rodenticide.

There has been pioneering laboratory work taking place in China and at Sokoine University in Tanzania on using hormones to reduce the prolific breeding rates of rats, and Belmain believes in time this could be used as a successful strategy.

Until then the fear remains that rodents can act as a ‘bridge’ between wild animals and livestock on British farms creating the perfect opportunity for outbreaks of disease.

That is why he argues it is so vital to bring numbers down. ‘If you are suddenly creating an environmental situation through food production or waste production that facilitates rodent density then we are creating the perfect storm for rodent transmission of disease and spillover events into humans,’ he says.

Unless we start making a significant dent in the rat population, Belmain admits, we remain locked in something of a stalemate against our centuries-old nemesis.

‘I don’t know if we will ever win the war on rats to be honest,’ he says. But if we are not careful, perhaps the rats may help spawn a disease which will enable them to finally triumph over us.

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