About this guide
This guide covers the diseases that rats carry and transmit in the UK — including Weil's disease (leptospirosis), Seoul virus (a hantavirus), rat bite fever, and salmonellosis — their public health significance, routes of transmission, and the symptoms that warrant urgent medical attention. The page supports Apex Pest Control Ltd's rat control service by explaining the health risks that make professional rat removal a priority rather than a preference.
Brown rats (Rattus norvegicus) are reservoir hosts for several pathogens that pose genuine public health risks in the UK. They do not need to bite or be visibly present to transmit disease — indirect contact through contaminated water, food, or surfaces is sufficient for some of the most serious infections.
Understanding the diseases rats carry and how transmission occurs is important context for anyone dealing with a rat infestation, or working or living in environments where rat contact is possible.
Weil's disease (leptospirosis)
Leptospirosis is the most significant rat-borne disease risk in the UK. The severe form, Weil's disease, causes potentially fatal organ failure affecting the liver and kidneys.
The pathogen, Leptospira interrogans, is shed in rat urine and can survive in fresh water and damp soil for several weeks. Human infection occurs through skin abrasions, mucous membranes, or eyes coming into contact with contaminated water. Sewage workers, waterways users, farmers, and anyone with a rat infestation in or near their property face elevated risk.
Initial symptoms — fever, severe headache, muscle pain, and conjunctivitis — typically appear 2–30 days after exposure and are often mistaken for influenza. In a minority of cases, the illness progresses to Weil's disease, with jaundice, kidney failure, and haemorrhage. Weil's disease has a case fatality rate of approximately 5–15% without prompt treatment. Leptospirosis is a notifiable disease in England and Wales.
The UK Health Security Agency (UKHSA) records 50–80 confirmed leptospirosis cases per year in England and Wales, with underreporting likely due to variable clinical presentation.
The UK Health Security Agency recorded 56 confirmed cases of leptospirosis in England and Wales in 2022, with outdoor water-based activities and occupational exposure to rodent-contaminated environments identified as the primary risk factors.
— UKHSA Leptospirosis Annual Report, 2022
Seoul virus (a hantavirus)
Seoul virus is the hantavirus strain carried by brown rats in the UK. Hantaviruses are shed in rodent urine, faeces, and saliva; human infection occurs through inhalation of contaminated dust, direct contact with infected rodents, or rodent bites. Seoul virus causes haemorrhagic fever with renal syndrome (HFRS), characterised by fever, back pain, and kidney dysfunction.
The first confirmed UK cluster of Seoul virus was identified in 2012 following investigation of cases among pet rat owners and breeders. Subsequent surveys by Public Health England found Seoul virus antibodies in approximately 1.5% of wild brown rats tested, with higher prevalence in some populations. Seoul virus has been confirmed in wild rat populations across England, Scotland, and Wales.
Seoul virus infection in humans is typically self-limiting but can cause serious renal impairment in some cases. It is a notifiable disease. Clinical suspicion should be raised in anyone with unexplained fever and kidney involvement following rodent exposure.
If you are clearing a space with known or suspected rat activity — a loft, cellar, outbuilding, or void — wear an FFP2 or FFP3 respirator, disposable gloves, and eye protection. Do not sweep or vacuum dry rodent droppings, as this disperses pathogen-containing particles into the air. Dampen the area with disinfectant first, then remove with disposable cloths. Bag all material for disposal.
Rat bite fever
Rat bite fever is caused by Streptobacillus moniliformis (in the UK and most of Europe) and transmitted through bites, scratches, or handling of infected rats. It can also occur through consumption of food or water contaminated with rat urine or faeces (Haverhill fever).
Symptoms develop 3–10 days after exposure and include fever, headache, muscle pain, and a distinctive rash on the palms and soles. Without treatment with antibiotics, the condition can be severe. Rat bite fever is rare in the UK but cases do occur, particularly among pest control workers, laboratory staff, and pet rat owners.
Salmonellosis and food contamination
Rats carry and shed Salmonella bacteria in their faeces, urine, and fur. In domestic and food production environments, rats contaminate food contact surfaces, packaging, ingredients, and stored food. Salmonella infection in humans causes gastroenteritis — nausea, vomiting, diarrhoea, and abdominal cramps — typically within 12–72 hours of consuming contaminated food or water. Most cases resolve without specific treatment, but severe infection can require hospitalisation, particularly in young children, the elderly, or immunocompromised individuals.
Businesses in the food sector have a legal obligation under the Food Safety Act 1990 to ensure premises are free from rodent contamination. A confirmed rat infestation that results in food contamination can lead to prohibition notices, prosecution, and reputational damage.
Cryptosporidiosis and other zoonotic risks
Rats may also carry Cryptosporidium (a waterborne parasite causing diarrhoeal illness), Toxoplasma gondii, and various other zoonotic pathogens. The risk from any individual pathogen depends on the local rat population, the nature of contact, and the immune status of the exposed individual. Immunocompromised individuals should treat any rat contact as a potential health risk and seek medical advice promptly.
How to reduce disease risk from a rat infestation
The most effective risk reduction measure is the prompt removal of the rat population and the elimination of access to the building. While this is being arranged or in progress, practical precautions include wearing gloves and a respirator when entering areas of known activity, keeping food in sealed containers, washing hands after any contact with areas of rodent activity, avoiding direct contact with rodent carcasses without protection, and seeking medical advice promptly if symptoms develop following known or possible rodent exposure.
Frequently Asked Questions
What disease is most commonly associated with rats in the UK?
Weil's disease (leptospirosis) is the most clinically significant rat-borne disease in the UK. It is transmitted through contact with rat urine in water or damp environments and can cause fatal liver and kidney failure if not treated promptly. It is a notifiable disease in England and Wales.
Is hantavirus a risk from UK rats?
Yes. Seoul virus — a hantavirus — has been confirmed in wild brown rat populations across England, Scotland, and Wales. It causes haemorrhagic fever with renal syndrome (HFRS) in humans. Always refer to it as Seoul virus (a hantavirus) when discussing the UK strain, rather than generic hantavirus, which encompasses different strains found in other countries.
Can you catch disease from rat droppings without touching them?
Yes. Inhalation of dust disturbed from dried rat droppings and urine-contaminated material is a documented transmission route for Seoul virus and potentially for other pathogens. When clearing areas with known rat activity, always dampen droppings with disinfectant before removal, wear a respirator (FFP2 minimum), and use disposable gloves.
How long does leptospirosis take to show symptoms?
The incubation period for leptospirosis is typically 2–30 days, with most cases presenting within 5–14 days of exposure. Initial symptoms — fever, headache, and severe muscle pain — are easily confused with influenza. If Weil's disease develops, jaundice and kidney failure follow. Anyone with these symptoms after known water exposure or rat contact should seek urgent medical attention.
Are rat diseases a risk even if rats are not seen?
Yes. Contamination from rat urine can persist in water and on surfaces for extended periods without the rats being visible. Leptospirosis, for example, has been contracted from apparently clean-looking water in drainage channels, canals, and flooded environments where rats had been present.
Should I wear protective equipment when clearing a rat-infested area?
Yes. Use disposable gloves, an FFP2 or FFP3 respirator, and eye protection. Do not sweep or vacuum dry droppings. Dampen the area with disinfectant first, then remove with disposable cloths. Bag all contaminated material and wash hands thoroughly after removal of PPE.
Can rats transmit disease to pets as well as humans?
Yes. Rats can transmit leptospirosis to dogs — this is a recognised and potentially fatal risk, particularly for dogs with access to ditches, canals, and waterways. Dogs can be vaccinated against the most common leptospirosis serovars. Cats, while natural rat predators, can also be exposed. Consult your vet if your pet has been in contact with rats or rat-contaminated environments.