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Understanding Weil’s Disease

Understanding Weil’s Disease

Weil’s disease is rare in the UK, but it is something cold water swimmers should take precautions towards, as it can be life-threatening.

Here at CWS, we take you through Weil’s disease, the risks, the symptoms and how best to prevent infection.

Understanding Weil’s disease is important – continue to learn more about protecting yourself from this illness.

What is Weil’s?

Weil’s disease, also known as Leptospirosis, is a bacterial infection caused by the Leptospira bacteria. The disease is primarily spread through the urine of infected animals, including rats, mice, cattle, and dogs.

Humans can contract the disease by coming into contact with water or soil contaminated with the urine of infected animals.

You can contract the infection either through an open wound or by consuming contaminated food or water – meaning many individuals could be at risk of infection.

So, no drinking open water unless you are sure it is clean!

What is Weil’s?
Weeds by a lake

Who is at risk of contracting Weil’s Disease?

Anyone who comes into contact with the urine of infected animals, either through water or soil, is at risk of contracting Weil’s Disease.

However, some people who may be at higher risk include:

  1. Farmers, abattoir workers and agricultural workers who work with animals or in areas with standing water
  2. Veterinarians and animal handlers
  3. Sewer workers, construction workers and garbage collectors
  4. Military personnel engaged in outdoor activities or field exercises
  5. People who participate in water sports, such as wild water swimming, canoeing, or swimming in contaminated water sources
  6. Travellers to areas where the disease is prevalent, such as tropical or subtropical environments like Australia.

It is important to note that cases of leptospirosis are rare in developed countries, such as England, with good sanitation practices and access to clean water. Check out the study from Health Protection Agency.

However, it is still a potential risk, so taking appropriate precautions to avoid contact with contaminated water and soil is essential to prevent the risk of leptospirosis infection.

Leptospirosis: how does the infection spread?

Common routes of transmission for Weil’s disease, or leptospirosis, include:

  1. Contact with water or soil contaminated with the urine of an infected animal, such as rodents, cattle, pigs, dogs, or wild animals.
  2. Direct contact with urine or tissues of infected animals.
  3. Consumption of contaminated food or water (yuck).
  4. Occupational exposure among workers who handle animals or work in outdoor environments, such as farmers, sewage workers, and military personnel.
  5. Recreational activities, like swimming or wading in contaminated water or participating in water sports in contaminated water sources, especially in a body of water like a canal.
  6. Swimming after heavy rainfall can also increase the chance of catching the disease.

It is important to note that human-to-human transmission of Leptospirosis is rare, although it can occur through sexual contact, blood transfusions, or organ transplantation from an infected donor.

Leptospirosis: how does the infection spread?
Rural River

How does leptospirosis develop?

The bacteria can enter the body through small cuts or abrasions in the skin or through the mucous membranes of the eyes, nose, or mouth.

So, if you are cold water swimming remember to put plasters on any open wounds, no matter how small!

They then spread through the bloodstream, infecting various organs and tissues, including the kidneys, liver, and brain.

In some cases, the infection can lead to a severe form of Weil’s disease, which can cause liver and kidney failure, bleeding, and even death.

Fortunately, the disease comes in two phases which gives you time to recognise the symptoms of leptospirosis and seek medical help.

First phase

The first phase brings flu-like symptoms; severe headache, chills, muscle pain, nausea and vomiting are all early signs of leptospirosis which could last 3 to 5 days.

In some cases, people can fully recover after the first phases but are still susceptible to fatigue and depression.

If you experience any of the noted symptoms, please see a doctor, as even if it isn’t Weil’s disease, it could be worth checking out!

Second phase

The second phase happens when the initial symptoms persist and become more severe. Severe cases lead to jaundice, red eyes, abdominal pain and diarrhoea – symptoms similar to meningitis.

Severe leptospirosis cases can cause kidney or liver failure; some may even die due to heart or respiratory distress.

As the disease can be so dangerous, you must treat the disease with reverence and take every precaution to avoid infection.

Top tips for avoiding Weil’s Disease

We’ve gathered top tips to help you avoid Weil’s and other infectious diseases while swimming in cold water.

1. Keep cuts covered

Keep any cuts or open wounds covered whilst swimming; waterproof plasters are ideal.

Dry suits can also help and are preferred over wetsuits as they keep your body dry and don’t allow water to contact your skin.

Whereas wetsuits keep a thin layer of water between your body and the suit, so there’s still a chance of infection.

2. Shower after swimming

Always wash your body thoroughly with soap and water after swimming in areas where there may be contaminated water.

A quick scrub in the shower will help to keep infection away!

3. Avoid the water’s edge

Whether at the water’s edge or swimming deep in the water, there’s a risk of contracting Weil’s disease.

However, there may be a higher risk of exposure to contaminated water and soil at the water’s edge, where animals may have urinated or defecated. 

So, stay away from river banks and edges. You can take a buoyant wetsuit or tow float to help you stay afloat without having to grab onto the side.

4. Boost your immune system

While there is no guaranteed way to boost your immune system to prevent Weil’s Disease or leptospirosis, there are some general steps you can take to support your immune system and reduce your risk of infection:

  1. Maintain a healthy diet: A healthy, balanced diet with plenty of fruits, vegetables, whole grains, lean proteins, and healthy fats can help support your immune system.
  2. Get enough sleep: Lack of sleep can weaken your immune system, so it’s important to get enough sleep each night to help keep your immune system functioning properly.
  3. Stay hydrated: Drinking plenty of water and staying hydrated can help support your immune system.

5. Head to the sea!

There’s less chance of contracting Weil’s disease in the ocean due to its sheer size and tides.

However, it is still possible to contract the disease in seawater if it is contaminated with animal urine or faeces.

Head to the sea!
Woman in the evening sea

6. Consult a doctor

A doctor may suggest getting vaccinated against the disease if you regularly find yourself in areas of possible contamination.

Also, seeing a doctor for early diagnosis and treatment of leptospirosis if showing symptoms of the disease will help you overcome it before the symptoms get worse.


Weils disease can sound quite worrying to us cold water swimmers, but if you take the necessary steps when swimming in the open, you will be fine.

Understanding Weil’s disease is the most important thing, as you can scout safe locations to take the plunge and act quickly if you start to feel any symptoms.