What is Leptospirosis?

Leptospirosis is a severe bacterial infection caused by exposure to the Leptospira bacteria. Outbreaks commonly occur when people are exposed to water that is contaminated with urine from infected animals after heavy rains and flooding.

Many different kinds of wild and domestic animals carry the bacteria.  These animals include cattle, pigs, horses, dogs, rodents, and other wild animals.

How do you get Leptospirosis?

Infected animals excrete the bacteria into the environment.  Humans become infected through contact with body fluids (mostly urine) from infected animals or through contact with water, soil or food contaminated with the urine of infected animals.  Bacteria enter the body through skin or mucous membranes (eyes, nose or mouth), especially through a cut or scratch.  

The risk of acquiring leptospirosis is highest during periods of heavy rainfall or flooding, but the infection can also be acquired through recreational water activities like white water rafting, swimming in rivers, or kayaking.

Susceptibility and Resistance

Generally, all persons are susceptible to leptospirosis infection in the absence of any previous exposure.  

After acute infection and illness, some immunity does develop but not against all types of the Leptospira bacteria.

Incubation Period

The incubation period for Leptospirosis is 2-20 days.

What are the Symptoms?

Leptospirosis can cause a wide variety of symptoms or, in some cases, no symptoms at all. It is often mistaken for other diseases, but a diagnosis can be confirmed by laboratory testing of a blood or urine sample. Infection with leptospirosis usually results in the sudden onset of high fever, muscle aches, dry coughing, vomiting, diarrhoea, and severe headache. Other early symptoms include abdominal pain, swelling of the eyelids, and a skin rash.  In 5-15 percent of cases, the infection progresses to a more severe form known as Weil's disease, which includes late phase complications, such as jaundice, kidney failure, abnormal heart rhythms, haemorrhage, respiratory problems, and low blood pressure. The mortality rate for patients with this severe form of leptospirosis ranges from 5 to 15 percent.

Preventative Measures

Travellers can greatly reduce the risk of acquiring leptospirosis by avoiding swimming or wading in water that might be contaminated by animal urine. Flood waters after heavy rainfall are often contaminated, and protective clothing, such as high rubber boots, should be worn if exposure to flood waters is likely.


Leptospirosis is often misdiagnosed as it shares symptoms with many other diseases and also because health-care providers in many countries may not suspect the disease if they are unaware their patient has travelled in a high risk area or has been involved in a rescue operation in flooded areas.

Leptospirosis is treated with antibiotics (particularly penicillin G and oral doxycycline).  Treatment should be started as soon as possible once leptospirosis is suspected to prevent its progression to the severe form of the disease. Intravenous penicillin, along with hospitalization and extensive supportive care, is necessary for the treatment of severe leptospirosis. 


Where Does It Commonly Occur?

This infection is common throughout the world in tropical and subtropical regions, especially in island countries. Outside of tropical areas, cases usually occur in the spring and autumn.