Leptospirosis: A Clinician's Guide to Spread, Symptoms, Testing and Treatment

Leptospirosis is a bacterial disease of people and animals, and one of the world's leading causes of illness passed from animals to humans. It is easy to miss: its symptoms look like many other conditions, and some people carry it with no symptoms at all.

Three things to remember

• Tell patients to keep out of water that animal urine may have contaminated — especially after hurricanes, flooding or heavy rain.
• If you strongly suspect leptospirosis, start antibiotics at once — don't wait for test results.
• For urgent help with a patient, CDC's experts are available around the clock (see below).

The bacterium

Leptospirosis is caused by Leptospira, long, thin, mobile spirochete bacteria.

• They leave infected animals in urine and other body fluids — livestock, pets, rodents, marine mammals and wildlife.
• In fresh water and wet soil in warm places they survive for weeks to months.
• They fall into more than 300 disease-causing serovars, grouped by their antigens — though a serovar doesn't predict the species. Which serovars and species occur varies by region.

How common it is

• About 1 million cases a year worldwide, and nearly 60,000 deaths — and because it is under-diagnosed and under-reported, the real numbers are probably higher.
• It is found worldwide, most often in tropical and subtropical climates, and has been reported from many U.S. states and jurisdictions.
• Cases rise after hurricanes and floods, when people wade through contaminated water or have to drink or wash in it.

Signs and symptoms

Incubation: usually 5–14 days, but anywhere from 2 to 30.

Untreated, it can lead to kidney failure, liver failure, jaundice, respiratory distress or failure and meningitis. In 5–10% of cases, multiorgan failure and death follow.

Testing

• Look for Leptospira DNA in blood, serum, urine or — if there are neurological signs — cerebrospinal fluid, or for the body's antibody response.
• Which test depends on how long the patient has had symptoms.
• CDC does not recommend testing people without symptoms.

Treatment

Treating early may make the illness milder and shorter. With high clinical suspicion, start antibiotics as soon as possible, before laboratory results.

Mild illness — doxycycline is the drug of choice unless contraindicated:

Severe illness

After an exposure

CDC has no standard recommendation for antibiotics to prevent leptospirosis (post-exposure prophylaxis, PEP) in someone without symptoms who touched an animal known or suspected to be infected. Evidence that PEP works is limited, and widespread antibiotic use risks drug resistance, so patients and clinicians should decide case by case.

Prevention

People lower their risk by not drinking, bathing, swimming or wading in water that might hold animal urine — especially after hurricanes or floods — and by avoiding animals that may be infected. More: CDC's page on leptospirosis.

Getting expert help

CDC's Bacterial Special Pathogens Branch (BSPB) consults 24/7 on urgent patient-management questions.

CDC's leptospirosis fact sheet for clinicians is also available in Spanish.

Sources

Based on "Clinical Overview of Leptospirosis," Centers for Disease Control and Prevention; a work of the United States government in the public domain.