Leptospirosis (Weil's disease)

What is leptospirosis?

Leptospirosis is a disease caused by bacteria that can be passed from infected animals to humans. In New York City, infected rats are the main source of leptospirosis.

How does leptospirosis spread?

Leptospirosis can enter the body through the eyes, nose, mouth, wounds or cuts in the skin. It can also be spread through exposure to outdoor freshwater or flood waters in tropical regions. People who have close contact with infected animals, especially rats, are at risk. Leptospirosis is not usually spread by people.

What are the symptoms of leptospirosis?

People can become sick between two days and four weeks after exposure. Some people who are infected may have no symptoms, while others may have a mild illness with fever, headache, chills, muscle aches, vomiting or diarrhea. Rarely, people who are infected may develop a life-threatening illness that affects their kidneys and liver.

What is the treatment for leptospirosis?

See a doctor if you think you may be infected with leptospirosis. Your doctor may take blood tests and start treatment with antibiotics, such as doxycycline or penicillin.

How can leptospirosis be prevented?

  • Avoid contact with rats or places where rats may have urinated.
  • If you cannot avoid areas where rats have been seen, or if you are cleaning areas where rats have been, use a solution of one part household bleach and ten parts water to kill the leptospirosis bacteria.
  • You can protect yourself from contact with rat urine by wearing rubber gloves, especially if you have cuts or sores on your hands or arms. You can also wear boots, masks and some type of eyewear.
  • Wash your hands carefully with soap and water after any contact with areas where rats may live.
  • Always wear shoes whenever taking trash to your trash compactor room.

Are my pets at risk?

Dogs can also get leptospirosis. Ask your veterinarian if your dog needs to be vaccinated. Signs that your dog may have the disease include fatigue, loss of appetite and vomiting. For more information about leptospirosis in dogs, read Leptospirosis Factsheet for Dog Owners (PDF)
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How common is leptospirosis in New York City?

Leptospirosis is not very common in NYC. An average of three human cases of leptospirosis are reported in the city each year. There may be additional cases that go undiagnosed because symptoms range and can be minor. Cases of leptospirosis are also reported in dogs. Click here to learn more.

Additional Resources

Download the Leptospirosis FAQ (PDF), also available in [Español].