Leptospira bacteria can be found in fresh water that has been soiled by animal urine. You may get infected if you consume or come in contact with contaminated water or soil. The infection occurs in warmer climates. Leptospirosis is not spread from person to person, except in very rare cases.

Risk factors include:

• Occupational exposure -- farmers, ranchers, slaughterhouse workers, trappers, veterinarians, loggers, sewer workers, rice field workers, and military personnel
• Recreational activities -- fresh water swimming, canoeing, kayaking, and trail biking in warm areas
• Household exposure -- pet dogs, domesticated livestock, rainwater catchment systems, and infected rodents

Weil disease, a severe form of leptospirosis, is rare in the continental United States. Hawaii has the highest number of cases in the United States.

Symptoms can take 2 to 30 days (average 10 days) to develop, and may include:

• Dry cough
• Fever
• Headache
• Muscle pain
• Nausea, vomiting, and diarrhea
• Shaking chills

Less common symptoms include:

• Abdominal pain
• Abnormal lung sounds
• Bone pain
• Conjunctival (surface of the whites of the eyes) redness without fluid
• Enlarged lymph glands
• Enlarged spleen or liver
• Joint aches
• Muscle rigidity
• Muscle tenderness
• Skin rash
• Sore throat

The blood is tested for antibodies to the bacteria. During some phases of the illness, the bacteria themselves can be detected using polymerase chain reaction (PCR) testing.

Other tests that may be done:

• Complete blood count (CBC)
• Creatine kinase
• Liver enzymes
• Urinalysis
• Blood cultures

Medicines to treat leptospirosis include:

• Ampicillin
• Azithromycin
• Ceftriaxone
• Doxycycline
• Penicillin

Complicated or serious cases may need supportive care. You may need treatment in a hospital intensive care unit (ICU).

The outlook is generally good. However, a complicated case can be fatal if it is not treated promptly.

Complications may include:

• Jarisch-Herxheimer reaction when penicillin is given
• Meningitis
• Severe bleeding

Contact your health care provider if you have any symptoms of, or risk factors for, leptospirosis.

Avoid areas of stagnant water or floodwater, especially in tropical climates. If you are exposed to a high risk area, take precautions to avoid infection. Wear protective clothing, shoes, or boots when near water or soil contaminated with animal urine. You can take doxycycline to decrease the risk.

Weil disease; Icterohemorrhagic fever; Swineherd's disease; Rice-field fever; Cane-cutter fever; Swamp fever; Mud fever; Hemorrhagic jaundice; Stuttgart disease; Canicola fever

Haake DA. Leptospirosis. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 298.

Haake DA, Levett PN. Leptospira species (leptospirosis). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 239.

Nemhauser J, Halsey E. CDC Yellow Book 2024: Health Information for International Travel. Centers for Disease Control and Prevention. wwwnc.cdc.gov/travel/page/yellowbook-home. Updated August 15, 2023. Accessed September 30, 2024.

Updated by: Jatin M. Vyas, MD, PhD, Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.