Find information on medical topics, symptoms, drugs, procedures, news and more, written in everyday language.

Leptospirosis +lep-tu-spI-!rO-sus

by Matthew E. Levison, MD

Leptospirosis is a potentially serious disorder caused by Leptospira bacteria.

  • Most people are infected through contact with contaminated soil or water during outdoor activities.

  • Fever, headache, and other symptoms occur in two phases, separated by a few days.

  • A severe, potentially fatal form damages many organs, including the liver and kidneys.

  • Detecting antibodies against the bacteria in blood or identifying the bacteria in a sample taken from infected tissue confirms the diagnosis.

  • Antibiotics and sometimes fluids containing salts are given, but people with the severe form may require transfusions and hemodialysis.

Leptospirosis occurs in many wild and domestic animals. Some animals act as carriers and pass the bacteria in their urine. Others become ill and die. People acquire these infections directly through infected animals or indirectly through soil or water contaminated by urine from an infected animal.

Leptospirosis is an occupational disease of farmers and sewer and slaughterhouse workers. However, most people become infected during outdoor activities when they come in contact with contaminated soil or water, particularly while swimming or wading. The 40 to 100 infections reported every year in the United States occur mainly in the late summer and early fall. Because mild leptospirosis typically causes vague, flu-like symptoms that go away on their own, many infections are probably unreported.


In about 90% of infected people, symptoms are mild. In the rest, the disorder involves many organs. This potentially fatal form of leptospirosis is called Weil’s syndrome.

Leptospirosis usually occurs in two phases:

  • First phase: About 2 to 20 days after infection occurs, fever, headache, nausea, vomiting, severe muscle aches in the calves and back, and chills occur suddenly. The eyes usually become very red on the third or fourth day. Some people cough, occasionally bringing up blood, and have chest pain. Most people recover within 1 week.

  • Second (immune) phase: In some people, symptoms recur a few days later. They result from inflammation caused by the immune system as it eliminates the bacteria from the body. The fever returns, and the space within the tissues covering the brain and spinal cord (meninges) often becomes inflamed. This inflammation (meningitis) causes a stiff neck and headache.

Weil’s Syndrome

This form can occur during the second phase. It causes jaundice (yellowish discoloration of the skin and whites of the eyes), kidney failure, and a tendency to bleed. People may have nosebleeds or cough up blood, or bleeding may occur within tissues in the skin, lungs, and, less commonly, digestive tract. Anemia can develop. Several organs such as the heart, lungs, and kidneys may stop functioning.

Most people who do not develop jaundice recover. About 5 to 10% of people with jaundice (which indicates liver damage) die. The death rate is probably higher in people with Weil’s syndrome and people over 60. If leptospirosis develops during early pregnancy, the risk of miscarriage is increased.


To confirm the diagnosis, doctors take a sample of blood and urine. These samples are analyzed. If people have symptoms of meningitis, doctors do a spinal tap (lumbar puncture) to obtain a sample of the fluid that surrounds the brain and spinal cord (cerebrospinal fluid). Usually, several samples are taken over several weeks. These samples are sent to a laboratory to grow (culture) the bacteria.

Identifying the bacteria in cultures or, more commonly, detecting antibodies against the bacteria in blood confirms the diagnosis.

Prevention and Treatment

The antibiotic doxycycline can prevent leptospirosis. It is given to people who were exposed to the bacteria at the same time as people who have been infected.

Mild infections are treated with antibiotics such as amoxicillin or doxycycline, given by mouth. For severe infections, antibiotics such as penicillin, doxycycline, or erythromycin may be given intravenously. Fluids containing salts may also be given. People with the infection do not have to be isolated, but care must be taken when handling and disposing of their urine.

People with Weil’s syndrome may need blood transfusions and hemodialysis.

Drugs Mentioned In This Article

  • Generic Name
    Select Brand Names