Leptospirosis (Weil’s Disease): Prevention and Risks for UK Travellers

Leptospirosis is a zoonotic bacterial infection caused by the Leptospira genus of bacteria. While it is present in the UK, it is significantly more common in tropical and subtropical regions where heavy rainfall and flooding occur. The bacteria are carried in the urine of animals—most commonly rats, but also cattle, pigs, and dogs—and can survive for weeks in freshwater and soil.

For British travellers, the risk typically arises when the bacteria enter the body through the eyes, mouth, nose, or breaks in the skin during water-based activities. If the infection becomes severe, it is known as Weil’s disease, a condition that can lead to organ failure and requires urgent hospitalisation.

According to NHS guidance, leptospirosis symptoms usually appear between 7 and 14 days after exposure, though the incubation period can range from 2 to 30 days. The illness often begins abruptly and can feel like a severe case of influenza.

• High temperature: A sudden fever often accompanied by chills.
• Muscle aches: Particularly in the calves and lower back.
• Headache: Often severe and persistent.
• Gastrointestinal issues: Nausea, vomiting, and loss of appetite.
• Red eyes: Conjunctival suffusion (redness without discharge).

In approximately 10% of cases, a second, more severe phase develops. This involves jaundice (yellowing of the skin and eyes), dark urine, and abdominal pain, indicating that the liver or kidneys are under stress. This progression is what constitutes Weil’s disease.

Where is the risk highest?

While leptospirosis is found worldwide, UK travellers should be particularly cautious in Southeast Asia, Central and South America, and the Caribbean. Outbreaks are often linked to extreme weather events; flooding can wash animal urine into local water systems, significantly increasing the bacterial load in rivers and lakes.

High-risk activities include:

• White-water rafting and kayaking in tropical rivers.
• Freshwater swimming or triathlons.
• Caving (potholing) where water runoff is present.
• Working in animal sanctuaries or farms abroad.
• Walking barefoot through mud or floodwaters.

NICE guidelines emphasise that prevention is the most effective way to avoid leptospirosis. If you are planning an adventurous holiday, consider these practical steps:

• Cover cuts and grazes: Use high-quality waterproof plasters to prevent bacteria from entering through the skin.
• Avoid submersion: Try to keep your head above water when swimming in lakes or rivers to avoid bacteria entering the nose or mouth.
• Wear protective footwear: Never walk barefoot in muddy areas or through standing water, especially after heavy rain.
• Shower immediately: Wash thoroughly with soap and clean water after participating in freshwater sports.
• Drink safe water: Only consume bottled or treated water; avoid swallowing water from natural sources.

If you have recently returned from a trip abroad and develop flu-like symptoms, it is important to seek medical advice quickly. You can speak to a GP online to discuss your travel history and symptoms. A doctor can help determine if your symptoms warrant blood tests or immediate antibiotic treatment.

Early intervention with antibiotics, such as doxycycline or penicillin, is highly effective at preventing the infection from progressing to the more dangerous Weil’s disease. During a GP consultation, be sure to mention exactly where you travelled and whether you had contact with freshwater or animals, as this information is vital for an accurate diagnosis.

Diagnosing leptospirosis can be challenging because its symptoms overlap with many other travel-related illnesses, such as malaria or dengue fever. A UK doctor will typically request a blood test or a urine sample to look for antibodies or the bacteria's DNA.

Treatment involves a course of antibiotics. In mild cases, these can be taken at home. However, if symptoms suggest liver or kidney involvement, the patient will be referred to a hospital for intravenous fluids and specialist monitoring. Most people make a full recovery if the infection is treated early, but fatigue can sometimes persist for several weeks following the acute phase.