Electron microscopy of many spirochetes


What is leptospirosis?

Leptospirosis is an infectious disease caused by spirochete bacteria belonging to the genus Leptospira. Many species of Leptospira have been described, some of which cause infections in humans. These bacteria have a helical shape and are very thin. They are highly motile and use their mobility to infect animals and humans. Leptospires penetrate through skin wounds or even insignificant cuts and through mucosae. They then migrate into the bloodstream, reaching various organs and eventually colonizing the kidneys.

How is leptospirosis transmitted?

Leptospirosis is a zoonosis that it is transmitted from animals to people. Although a wide variety of agricultural, companion, and wild animals can carry leptospirosis, the major reservoir host animals are rodents (rats and mice), pigs, cattle, and dogs. Animals shed leptospires from their kidneys into the environment. Leptospires can survive for weeks or months in freshwater or mud in wet or shaded areas. Humans acquire infection through direct contact with infected animals or indirect exposure to contaminated water or soil.

What are the signs and symptoms of leptospirosis?

The disease leptospirosis appears between 2 and 20 days after exposure and starts with high fever, headache, stiffness or joint pains. Severe cases involve jaundice, kidney disorders, breathing difficulty or cough and hemorrhage. In very severe cases, the patient can die from kidney or lung damage. The clinical criteria for diagnosis of leptospirosis provided by the CDC include fever, headache, and myalgia, and less frequently by conjunctival suffusion, meningitis, rash, jaundice, or renal insufficiency. Symptoms may be biphasic.

When should a test be performed to diagnose leptospirosis?

Diagnostic testing should be requested for patients in whom there is a high index of suspicion for leptospirosis, based either on signs and symptoms, or on occupational, recreational or vocational exposure to animals or environments contaminated with animal urine. The laboratory criteria for diagnosis of leptospirosis are available here.

Is leptospirosis a reportable disease in the United States?

Yes, in 2013 leptospirosis became reportable again in the United States. Cases of leptospirosis should be reported to your local health department.

Can I get leptospirosis from my dog?

Yes, leptospirosis is well known to be transmitted from dogs to people. Canine vaccines are available to reduce the risk of leptospirosis in your pet.

Can leptospirosis be cured?

It is extremely important to rapidly seek medical attention in the event of fever with headache, especially during rainy periods or after contact with rodents, dogs, pigs, or cattle or after walking barefoot or bathing in freshwater. Mild leptospirosis may resolve spontaneously without specific treatment. If antibiotics are not administered early in the course of infection, leptospirosis may progress to involve the liver, kidneys and sometimes the lungs. In man, symptoms may persist even after the infection is gone. Animals may be reservoir hosts and shed bacteria for longer periods of time.