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

Leptospirosis is a rare, severe, and contagious bacterial infection caused by several species of the genus Leptospira, a spiral-shaped microorganism (spirochete).

Causes, incidence, and risk factors

Leptospirosis is caused by exposure to the bacteria, which can be found in fresh water contaminated by animal urine. It occurs in warmer climates.

Risk factors include:

  • Occupational exposure - farmers, ranchers, abattoir 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 live stock, rainwater catchment systems, and infestation by infected rodents.

The incidence of leptospirosis is low in the continental U.S. Hawaii has the highest number of cases in the U.S.


  • Incubation period of 2 to 26 days (average 10 days)  
  • Abrupt onset of fever, rigors, myalgias, and headache in 75 to 100% of patients  
  • Dry cough (25-35% of cases)  
  • Nausea, vomiting, and diarrhea (50% of cases)  
  • Less common symptoms include joint aches, bone pain, sore throat, and abdominal pain  
  • Conjunctivitis  
  • Approximately 7 to 40% of patients may have muscle tenderness, an enlarged spleen or liver, enlarged lymph glands, sore throat, muscle rigidity, abnormal lung sounds, or skin rash

Signs and tests

  • White blood cell (WBC) counts are generally less than 10,000.  
  • Urinalysis frequently is abnormal.  
  • Elevated creatine kinase is found in approximately 50% of patients.  
  • About 40% of patients have minimal to moderate elevations of liver enzymes.  
  • Diagnosis is most frequently made by serologic (antibody) testing.  
  • Bacteria is best visualized by dark field microscopy, silver stain, or fluorescent microscopy.  
  • Unlike Treponema pallidum, Leptospira can be grown from blood, urine, and CSF. It is slow growing and the laboratory needs to be notified.  
  • Isolation of the organism from the blood is successful in 50% of cases.  
  • Urine cultures become positive during the second week of the illness and remain so for up to 30 days.


Penicillins, tetracyclines, chloramphenicol, and erythromycin can be given to treat leptospirosis. Supportive care needs to be given in complicated cases.

Expectations (prognosis)
Generally good, although deaths do occur in complicated cases if not treated promptly.


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

Calling your health care provider
If you have any of the signs, symptoms, or risk factors for leptospirosis, contact your health care provider.

Avoid areas of stagnant water, especially in tropical climates. If you are exposed to a high risk area, taking doxycycline may decrease your risk of developing disease.

Johns Hopkins patient information

Last revised: December 8, 2012
by Armen E. Martirosyan, M.D.

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