Leptospirosis is a rare, severe, and contagious infection caused by several types of the Leptospira bacteria.

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 - 26 days (average 10 days)
• Abrupt onset of fever, rigors, myalgias, and headache in 75 - 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 - 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

Diagnosis is most frequently done by testing the blood for antibodies to the bacteria.

Other tests may be done:

• A white blood cell count generally shows less than 10,000 white blood cells.
• Urinalysis is usually abnormal.
• Higher-than-normal creatine kinase is found in approximately 50% of patients.
• About 40% of patients have a slight to moderate increase in liver enzymes.

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

The outlook is generally good, although death is possible if a complicated case is not treated promptly.

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

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.