Leptospirosis is a rare bacterial infection that affects people and animals. It can pass from animals to humans when an unhealed break in the skin encounters water or soil where animal urine is present.

Several species of the Leptospira genus of bacteria cause leptospirosis. It can progress to conditions such as Weil’s disease or meningitis, which can be fatal.

The condition does not usually pass from one person to another.

The bacteria can enter the body through open wounds, the eyes, or mucous membranes. Animals that transmit the infection to humans include rats, skunks, opossums, foxes, and raccoons.

Leptospirosis is more common in tropical areas, where the World Health Organization (WHO) estimate that it affects 10 or more people in every 100,000 each year.

In temperate climates, it probably affects between 0.1 and 1 per 100,000 people. In an epidemic, it can affect 100 or more in every 100,000 people.

People traveling to tropical areas have a greater risk of exposure.

Leptospirosis is a bacterial infection.Share on Pinterest
Leptospirosis is a bacterial infection.

For mild cases, the doctor may prescribe antibiotics, such as doxycycline or penicillin.

Patients with severe leptospirosis will need to spend time in the hospital. They will receive antibiotics intravenously.

Depending on which organs leptospirosis affects, the individual may need a ventilator to help them breathe.

If it affects the kidneys, dialysis may be necessary.

Intravenous fluids can provide hydration and essential nutrients.

Hospital stays may range from a few weeks to several months. This mostly depends on how the patient responds to antibiotic treatment, and how severely the infection damages their organs.

During pregnancy, leptospirosis can affect the fetus. Anyone who has the infection during pregnancy will need to spend time in the hospital for monitoring.

The signs and symptoms of leptospirosis usually appear suddenly, about 5 to 14 days after infection. However, the incubation period can range from 2 to 30 days, according to the CDC.

Mild leptospirosis

Signs and symptoms of mild leptospirosis include:

Most people recover within a week without treatment, but around 10 percent go on to develop severe leptospirosis.

Severe leptospirosis

Signs and symptoms of severe leptospirosis will appear a few days after mild leptospirosis symptoms have disappeared.

Symptoms depend on which vital organs are involved. It can lead to kidney or liver failure, respiratory distress, and meningitis. These can be fatal.

The heart, liver, and kidneys

If leptospirosis affects the heart, liver, and kidneys, the person will experience:

  • fatigue
  • irregular, often fast, heartbeat
  • muscle pains
  • nausea
  • nosebleeds
  • pain in the chest
  • panting
  • poor appetite
  • swelling of the hands, feet, or ankles
  • unexplained weight loss
  • jaundice, seen in a yellowing of the whites of the eyes, tongue, and skin

Without treatment, this can lead to life-threatening kidney failure.

The brain

If it affects the brain or spinal cord, meningitis, encephalitis, or both may develop.

Meningitis is an infection of the membrane covering the brain and spinal cord, while encephalitis refers to infection of brain tissue. Both conditions have similar signs and symptoms.

These may include:

  • confusion or disorientation
  • drowsiness
  • fits or seizures
  • high fever
  • nausea
  • photophobia, or sensitivity to light
  • problems with physical movements
  • stiff neck
  • inability to speak
  • vomiting
  • aggressive or unusual behavior

Untreated meningitis or encephalitis can result in serious brain damage, and it may be life-threatening.

The lungs

If it affects the lungs, the person cannot breathe.

Signs and symptoms include:

  • high fever
  • panting
  • coughing up blood

In severe cases, there may be so much blood that the person suffocates.

Early-stage, mild leptospirosis is hard to diagnose, because the symptoms can resemble those of flu and other common infections.

If a physician suspects severe leptospirosis, the patient may undergo specific diagnostic tests. Various tests are available. In some cases, tests may need repeating to confirm the result.

The doctor will ask about any recent travel, especially to areas where leptospirosis is common.

They may ask if the person:

  • has been swimming in a lake, pond, canal, or river
  • has had contact with any activities that occurred in a slaughterhouse, on a farm, or relating to animal care
  • may have had contact with animal urine or blood

A number of blood and urine tests can confirm or rule out leptospirosis.

In the United States, leptospirosis is a notifiable disease. The doctor must inform the relevant health authorities if a person’s diagnosis confirms an infection.

There are two main types of leptospirosis.

Mild leptospirosis: This accounts for 90 percent of cases. Symptoms include muscle pain, chills, and possibly a headache.

Severe leptospirosis: Between 5 and 15 percent of cases can progress to severe leptospirosis. Organ failure, internal hemorrhaging, and death can result if the bacterium infects the liver, kidneys, and other major organs.

The Centers for Disease Control and Prevention (CDC) puts the fatality rate between 5 and 15 percent among those with severe illness.

With effective and timely treatment, leptospirosis is less likely to become severe.

Those more likely to develop severe leptospirosis tend to be those who are already sick, for example, with pneumonia, those under the age of 5 years, and those in older age.

Who is at risk?

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Drinking river water without boiling it or using chemical treatment increases the risk of leptospirosis and other diseases.

Leptospirosis is more common in a tropical climate, but it may also occur in the poorer parts of large cities in developing nations that are not in tropical areas.

The risk is higher at times of excessive rainfall and flooding, according to the WHO.

The bacterium thrives in hot and humid environments. It tends to be sporadic rather than constantly present.

Leptospirosis is more likely to occur in:

  • South and Southeast Asia
  • Australia
  • the Caribbean and Central America
  • the Andes and tropical Latin America
  • East Sub-Saharan Africa

Tourist hotspots where leptospirosis sometimes occurs include New Zealand, Australia, Hawaii, and Barbados.

Flooding increases the risk of an outbreak. If climate change leads to more cases of flooding around the world, leptospirosis may become more common.

Leptospirosis in the United States

Around 100 to 150 cases occur each year in the U.S., mostly in Puerto Rico and Hawaii, according to the CDC. The largest number of cases was in 1998, when 775 people were exposed.

In countries such as the U.S., with a developed infrastructure, those most at risk are:

  • sewage workers
  • farm and agricultural workers who have regular contact with animals or infected water or soil
  • pet shop employees and veterinarians
  • abattoir workers and meat handlers
  • those involved in recreational water sports, such as sailing or canoeing
  • military personnel

Death rates in developed nations are much lower than in poorer countries, due to effective health care.

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If you are going on a tropical holiday where you expect to do some water sports, see your doctor about precautions to take.

A number of measures can help reduce the risk of getting leptospirosis, especially among those whose leisure or work activities increase their risk.

Water sports: In non-tropical, developed nations, such as the U.S., the risk of leptospirosis is very small, and most people do not need to avoid doing water sports.

However, those who do watersports as part of a holiday adventure and those regularly swim in freshwater should take some precautions.

One is to make sure that any skin cuts are covered with a waterproof dressing.

This can protect against a range of infections, including hepatitis A and giardiasis.

After swimming in fresh water, it is a good idea to shower thoroughly.

Workplace exposure: Those who work with animals or potentially contaminated water or soil should wear protective clothing and comply with local or national rules and regulations.

They may need to wear gloves, masks, boots, and goggles.

Travel and tourism: People who travel to areas where leptospirosis is common should take the following steps:

  • Avoid swimming in fresh water.
  • Drink only water that is boiled or from a sealed bottle.
  • Clean and cover any skin wounds with a waterproof dressing.

Disaster response: Emergency workers or military personnel in disaster zones might have to take antibiotics as a precautionary measure.

Other tips

Other tips for avoiding leptospirosis include: where:

  • controlling pests, especially rodents
  • washing hands with soap and water after handling animals and animal products
  • avoiding touching dead animals with bare hands
  • cleaning all wounds as soon as possible and covering them with waterproof dressings
  • wearing protective clothing at work, if appropriate
  • avoiding wading, swimming, or other contact with rivers, streams, and lake water, especially after flooding, or shower at once after exposure
  • avoid contact with or consuming anything that has been in contact with flood water
  • avoiding drinking water from rivers and lakes unless it has been boiled or chemically treated
  • ensuring that dogs have a vaccination against leptospirosis

People can become infected through:

  • drinking contaminated water
  • unhealed cuts or wounds that come into contact with contaminated water or soil
  • the eyes, nose, or mouth coming into contact with contaminated water or soil
  • less commonly, contact with the blood of an infected animal

Infection rarely passes between humans, but this can sometimes happen during sexual intercourse or breastfeeding.

The Leptospira bacteria can exist in raccoons, bats, sheep, dogs, mice, rats, horses, cattle, buffaloes, and pigs.

The bacteria inhabit the animals’ kidneys and are expelled through urination, infecting the soil or water supplies.

The bacteria can remain in the soil or water for months.


I am going on a trip to a tropical area where I am hoping to do some white water rafting and other water sports. What precautions can I take?


The best way to prevent infection by leptospirosis is to avoid contact with bodies of water in areas where leptospirosis is common.

However, if activities that involve exposure to bodies of water are planned, the CDC say that a traveler can take an oral antibiotic called doxycycline once weekly to prevent infection by this bacteria.

The prophylaxis should be started 1-2 days before the exposure to water is set to happen.

Ask your doctor if this medication is recommended before you travel.

Daniel Murrell, MD Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

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