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Illness from Animals: Leptospirosis

Leptospirosis is a bacterial infection caused by species of Leptospira organisms that can infect domestic and wild animals. The bacteria is excreted in the animal’s urine and can survive in the soil or water for weeks or months. Humans can then become infected from the contaminated soil or water, often during activities like swimming or canoeing in lakes or rivers. The bacteria enter the body through cuts in the skin; through the nose, eyes, or mouth (mucosal membranes); or by swallowing contaminated water. It is very rare for the infection to spread from person to person. The time from exposure to the bacteria until beginning of illness is about a week, but sometimes can take as long as a month. Leptospirosis is an uncommon disease. The Centers for Disease Control and Prevention estimates that about 100 to 200 cases are identified each year in the United States, with about half of those cases occurring in Hawaii. It is more common in other parts of the world.

Signs and Symptoms

Illness seen with leptospirosis includes:

  • Fever and chills
  • Headaches
  • Muscle soreness in the calves and back
  • Redness of the eyes (conjunctivitis)
  • Abdominal pain, nausea, and vomiting
  • Skin rash over the shins (pretibial)

These symptoms may initially last for 3 to 7 days. Then there may be a short period (for 1 to 3 days) during which the fever goes away, followed by a second phase in which the fever returns, with any of the previously described symptoms as well as increased inflammation of the eye (uveitis, iritis), covering of the brain (meningitis), liver (hepatitis), and lymph nodes. The rash may become worse. At times, leptospirosis can be life threatening (Weil syndrome).When the infection goes untreated, liver infection (hepatitis) with yellowing of the skin and eyes (jaundice), bleeding, kidney failure, irregular heart rhythms, inflammation of the lining of the brain and spinal cord (meningitis), and a form of pneumonia called hemorrhagic pneumonitis may develop.

When to Call Your Pediatrician

Contact your pediatrician if your child has symptoms that suggest the presence of leptospirosis.

How Is the Diagnosis Made?

Most often, leptospirosis is diagnosed with antibody testing of blood samples. 


Your pediatrician will prescribe antibiotics to treat leptospirosis. Children with a mild infection can be treated with oral amoxicillin if they are younger than 8 years. Oral doxycycline is used for children 8 years and older. (In young children, tetracyclines such as doxycycline can cause staining of the teeth.) Some patients with leptospirosis become very ill and should be hospitalized to receive penicillin intravenously.

What Is the Prognosis? 

This disease can last from a few days to several weeks, but most children fully recover. Even so, some of the serious complications such as brain or spinal cord inflammation or kidney damage can cause lasting health problems. On rare occasions, death may occur. 


Make sure your child follows good hygiene habits. She should wash her hands frequently and avoid direct contact with the urine of pets and other animals. Your child should not play in and around dirty puddles of standing water in the outdoors. Although there is a vaccine to protect pets from leptospirosis, there is no vaccine approved for use in people.

Last Updated
Immunizations & Infectious Diseases: An Informed Parent's Guide (Copyright © 2006 American Academy of Pediatrics)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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