What is Weil’s disease?

Weil’s disease is a severe form of leptospirosis. This is a type of bacterial infection. It’s caused by Leptospira bacteria.

You can contract it if you come into contact with the urine, blood, or tissue of animals or rodents that are infected with the bacteria. These may include:

  • cattle
  • pigs
  • dogs
  • rats

You can also contract it from contact with contaminated soil or water.

Leptospirosis typically causes mild flu-like symptoms, such as headache and chills. If the bacteria infect some specific organs, there may be a more severe reaction. These organs include:

  • liver
  • kidneys
  • lungs
  • heart
  • brain

This reaction is known as Weil’s disease. In rare cases, it can lead to organ failure and death.

If you’re diagnosed with leptospirosis, your doctor will prescribe a course of antibiotics to treat it. But if you develop Weil’s disease, you may need to be admitted to a hospital for extra care.

The symptoms of leptospirosis usually appear within 5 to 14 days after you become infected by Leptospira bacteria, reports the New York State Department of Health. But symptoms can develop anywhere from 2 to 30 days after infection, with an average of 10 days after initial exposure.

The presentation of leptospirosis is highly variable. In most cases of leptospirosis, your symptoms will be relatively mild. For example, you may experience:

  • fever
  • chills
  • muscle aches
  • headaches
  • cough
  • nausea
  • vomiting
  • loss of appetite

In rare cases, you may develop Weil’s disease, a severe form of leptospirosis. The symptoms of Weil’s disease usually develop one to three days after milder symptoms of leptospirosis have passed. The symptoms can vary depending on which organs are infected.

Liver, kidney, and heart

If your kidneys, liver, or heart become infected by Leptospira bacteria, you may experience:

  • nausea
  • loss of appetite
  • weight loss
  • fatigue
  • swollen ankles, feet, or hands
  • painful swelling of your liver
  • decreased urination
  • shortness of breath
  • rapid heartbeat
  • jaundice, a condition in which your skin and the white parts of your eyes become yellowish in color


If your brain becomes infected, your symptoms may include:

  • high fever
  • nausea
  • vomiting
  • neck rigidity or pain
  • drowsiness
  • confused mental state
  • aggressive behavior
  • seizures
  • inability to control your movements
  • inability to speak
  • aversion to lights


If your lungs become infected, your symptoms may include:

  • high fever
  • shortness of breath
  • coughing up blood

Weil’s disease is caused by Leptospira bacteria. If your infection is mild, it’s known as leptospirosis. If you develop a severe infection, it’s known as Weil’s disease.

Leptospira bacteria typically infect some farm animals, dogs, and rodents.

You can become infected with the bacteria if your eyes, mouth, nose, or open cuts on your skin come into contact with:

  • urine, blood, or tissue from an animal that carries the bacteria
  • water that’s contaminated with the bacteria
  • soil that’s contaminated with the bacteria

You can also contract leptospirosis if you’re bitten by an animal that is infected by it.

Leptospirosis is primarily an occupational disease. This means it’s usually work-related. It most commonly affects people who work in close proximity to animals, animal tissues, or animal waste products.

Animals known to spread leptospirosis to humans include:

  • cattle
  • pigs
  • dogs
  • reptiles and amphibians
  • rats and other rodents, which are the most important reservoir for the bacteria

People who are at a higher risk of contracting leptospirosis include:

  • farmers
  • veterinarians
  • freshwater fishermen
  • butchers and others who work with dead animals
  • people who engage in water sports, like swimming, canoeing, rafting, or kayaking
  • people who bathe in fresh water lakes, rivers, or canals
  • rodent control workers
  • sewer workers
  • soldiers
  • miners

Leptospirosis and Weil’s disease are found worldwide, but they’re more common in tropical regions than temperate zones.

If you develop a mild case of leptospirosis, it may be difficult to diagnose. The symptoms tend to resemble those of other conditions, such as the flu. Weil’s disease is easier to diagnose because the symptoms are more severe.

To make a diagnosis, your doctor will likely start by taking your medical history. Tell your doctor if you:

  • have recently travelled
  • have participated in water sports
  • have come in contact with a freshwater source
  • have an occupation that involves working with animals or animal products

If your doctor suspects you may have leptospirosis or another bacterial infection, they may order blood tests, urine tests, or both.

Laboratory staff can test a sample of your blood or urine for Leptospira bacteria. In the case of Weil’s disease, your doctor may also perform imaging scans, such as chest X-rays, and more bloodwork to check your liver and kidney function. Scans and tests can also help your doctor learn which of your organs may be infected.

Most cases of simple leptospirosis are mild and self-limiting, meaning they resolve on their own. If you’re diagnosed with Weil’s disease, you may be hospitalized. In the hospital, you will likely receive antibiotics intravenously. This will help clear the underlying bacterial infection. Penicillin and doxycycline are two of the preferred antibiotics.

You may also receive additional treatments, depending on your symptoms and which organs are affected. For example, if you’re having trouble breathing, you may be connected to a ventilator. If your kidneys have been infected and damaged, you may need to undergo dialysis.

Ask your doctor for more information about your diagnosis, treatment plan, and outlook.

If left untreated, Weil’s disease can lead to kidney failure, liver failure, or heart failure. In rare cases, it may result in death.

If you suspect you may have Weil’s disease, make an appointment with your doctor. Starting antibiotics quickly can greatly improve your chances of recovery. Your doctor may also prescribe other treatments to help manage potential complications.

Scientists have developed vaccines that seem to provide some protection against leptospirosis. Vaccines for humans are only available in some countries, such as Cuba and France. However, these vaccines may only protect against certain forms of Leptospira bacteria, and they may not provide long-term immunity.

There’s no vaccine available for humans in the United States, although vaccines are available for dogs, cattle, and some other animals.

If you work with animals or animal products, you can lower your risk of infection by wearing protective gear that includes:

  • waterproof shoes
  • goggles
  • gloves

You should also follow proper sanitation and rat-control measures to help prevent the spread of Leptospira bacteria. Rodents are one of the primary carriers of infection.

Avoid stagnant water and water from farm runoffs, and minimize animal contamination of food or food waste.