Leptospirosis is a type of bacterial infection spread by animals. It's caused by a strain of bacteria called leptospira.
In 90% of cases, leptospirosis only causes mild flu-like symptoms, such as a headache, chills and muscle pain.
However, in some cases the infection is more severe and can cause life-threatening problems, including organ failure and internal bleeding. In its most severe form, leptospirosis is also known as Weil's disease.
The common mild symptoms mean most leptospirosis infections are hard to diagnose. Diagnosis is easier if the infection causes more serious problems.
Why does leptospirosis happen?
Leptospirosis is spread to humans by animals.
You can catch it by touching soil or water contaminated with the urine of wild animals infected with the leptospira bacteria.
Animals known to be carriers of the leptospira bacteria include cattle, pigs, dogs and rodents, particularly rats.
Although the condition is uncommon in the UK, people who regularly deal with animals, such as farmers and vets, have a higher risk of developing leptospirosis.
You may also be at a higher risk if you frequently come into contact with rivers and lakes. This might be because of your occupation or through taking part in activities such as water sports and fishing.
It's incredibly rare for it to spread between humans.
When to see your GP
See your GP if you are experiencing symptoms of leptospirosis and you have recently:
travelled to parts of the world where leptospirosis is widespread
been exposed to a freshwater source, such as a river, lake, drain, canal, pond or flood water
been exposed to animal urine or animal blood – for example, if you work in farming, an abattoir, or care for animals (veterinary care)
A diagnosis of leptospirosis can be confirmed by running a series of blood and urine tests to check for specific antibodies.
Who is affected?
Leptospirosis is rare in the UK, with less than 40 cases reported in England and Wales every year. Many cases originate overseas and the condition is rarely fatal.
Most of the people affected either worked with livestock, or contracted the condition from sewage or freshwater sources.
Leptospirosis is more common in tropical and subtropical areas of the world.
Can leptospirosis be prevented?
The risk of contracting leptospirosis in the UK is so low you don't need to take drastic measures to avoid the condition.
If you work with animals – dead or alive – or are in regular contact with freshwater sources, you can help protect yourself from leptospirosis by wearing appropriate protective clothing and by cleaning and dressing wounds.
This advice is particularly useful if you 're travelling to an area where leptospirosis is more common.
How is leptospirosis treated?
Leptospirosis is treated with a course of antibiotics.
For mild forms of leptospirosis, antibiotic tablets that can be taken at home are usually used for about a week.
Most people with more severe leptospirosis will be admitted to hospital so their body's functions can be supported while the underlying infection is treated with injections of antibiotics.
If you may have contracted leptospirosis at your place of work, notify your employer so they can report it. If you're self-employed, you should report it yourself.
Symptoms of leptospirosis
The symptoms of leptospirosis usually develop suddenly around 7 to 14 days after exposure to the leptospira bacteria.
However, it is possible for symptoms to develop from between 2 and 30 days after exposure.
About 90% of leptospirosis infections only cause mild symptoms, including:
a high temperature (fever) that is usually between 38C and 40C (100.4-104-F)
nausea and vomiting
loss of appetite
muscle pain, particularly affecting the muscles in the calves and lower back
conjunctivitis (irritation and redness of the eyes)
a short-lived rash
These symptoms usually resolve within five to seven days. However, in about 10% of cases people go on to experience more serious symptoms.
Severe leptospirosis infections are sometimes called Weil's disease. The symptoms of a severe infection usually develop one to three days after the more mild symptoms have passed.
If the condition progresses to a severe infection, it may affect organs, including the brain, liver, kidneys, heart and lungs. This can lead to further symptoms, including:
jaundice (yellowing of the skin and the whites of the eyes)
swollen ankles, feet or hands
symptoms of meningitis or encephalitis, such as headaches, vomiting and seizures
shortness of breath
coughing up blood
If left untreated, the infection may be life threatening, and could lead to brain damage, kidney failure, internal bleeding and loss of lung function.
Causes of leptospirosis
Leptospirosis is caused by a strain of bacteria called leptospira, which is found in certain animals and can spread to humans.
Many different kinds of animals can carry the bacteria, but it is most commonly associated with:
rats and mice
farm animals, such as pigs, cattle, horses and sheep
It's rare to catch leptospirosis from domestic pets, although there have been cases where the infection was caught from pet rats.
An animal carrying the leptospira bacteria may show no outward signs of illness. The bacteria live inside the animal's kidneys and can be passed out in their urine. Bacteria can survive for several weeks, and even months, when it's passed into soil or water.
You can become infected with the leptospira bacteria if contaminated water or soil comes into contact with your eyes, mouth, nose, or any open cuts in the skin.
The bacteria can also be spread through rodent bites or by drinking contaminated water. Less commonly, it can be passed to humans who come into close physical contact with the blood or tissues of an infected animal.
Outbreaks of leptospirosis can also occur, particularly at events that involve close contact with infected water, such as some water sports, or after a flood.
It's extremely rare for it to be passed from human to human, but it may be possible during sex, or by an infected mother passing it on to her baby while breastfeeding.
Where is leptospirosis found?
Leptospirosis is found throughout the world, including Europe, but is most common in tropical and subtropical areas. This is because the leptospira bacteria are able to survive longest in hot and humid conditions.
Leptospirosis is most common in:
Central and South America
If you are travelling to these parts of the world, certain outdoor activities could bring you into contact with contaminated water or soil, placing you at a higher risk of contracting leptospirosis. For example:
camping in rural areas
sailing, rafting or canoeing
caving or potholing
Flooding also tends to be linked with outbreaks of leptospirosis, when drinking water becomes infected with contaminated flood water.
There are several occupations that increase your risk of contracting leptospirosis. This risk is most significant if you are working in higher risk countries, rather than in the UK. These occupations include:
farmers, particularly pig, cattle and rice farmers
people who regularly work with animals, such as vets
people who work with dead animals, such as butchers or abattoir workers
Leptospirosis is usually treated with a course of antibiotics, although their effectiveness has not been conclusively proven.
Most cases of leptospirosis are mild and are treated with a five to seven-day course of antibiotic tablets. Penicillin or a tetracycline antibiotic called doxycycline are the preferred choices.
It's important to finish the course of antibiotics, even if you are feeling better. This is because stopping treatment before all of the bacteria have been killed may trigger the infection to return.
Painkillers such as paracetamol and ibuprofen are available over the counter and can be used to help relieve symptoms such as a headache, a high temperature, and muscle pain.
If you develop a more severe leptospirosis infection, you will need to be admitted to hospital. The underlying infection will be treated with antibiotics injected directly into the bloodstream (intravenously).
If your organs have been damaged, the functions of your body may need to be supported. For example, you may need:
a ventilator to assist your breathing
dialysis, where the functions of your kidneys are artificially replicated by removing waste materials from your blood
intravenous fluids to restore the fluids and nutrients in your body
Some people may be well enough to leave hospital within a few weeks, while others may require several months of hospital care. It depends on how well you respond to antibiotics and the extent of any organ damage.
Leptospirosis and pregnancy
It's difficult to predict how a leptospirosis infection will affect pregnancy. In some cases, the infection can spread to the unborn child and be fatal.
If you develop the symptoms of leptospirosis during pregnancy (even mild symptoms), you may be admitted to hospital so you can be monitored.
Although leptospirosis is rare in the UK, some simple steps can help reduce your chances of developing the condition.
Water sports in the UK
Rates of leptospirosis are very low in the UK, so there's no reason why you should not participate in freshwater activities such as swimming, sailing, water-skiing or windsurfing.
However, it is a sensible precaution to cover any cuts and grazes with a waterproof dressing and shower or bathe afterwards.
This will also help protect against other waterborne infections, such ashepatitis A or giardiasis.
You should wear adequate protective clothing if you have an occupation where you come into contact with animals (particularly rodents) or sources of contaminated water, such as farming or working with sewers or drains.
If you are travelling to parts of the world where leptospirosis is widespread, you may wish to limit your exposure to freshwater sources, such as rivers, ponds or lakes. If you are unable to avoid these, you should wear adequate protective clothing.
You should also only drink sealed bottled water or fresh water that has been boiled. Always cover any cuts or grazes with waterproof dressings and clean any wounds as soon as possible.
Avoid areas where animals may have urinated. If you suspect you have been exposed to animal urine, clean the affected area of skin as soon as possible. Never touch a dead animal with your bare hands.
Antibiotics can sometimes be taken as a precaution against becoming infected. But there is limited evidence this works for leptospirosis, so the treatment is usually only used in exceptional circumstances:
for emergency workers working in disaster zones where there is known to be an outbreak of leptospirosis cases
for soldiers serving in areas where rates of leptospirosis are high
for animal workers contaminated by an animal known to be a carrier of the leptospira bacteria
At the moment, there isn't a vaccine that protects humans from leptospirosis, but it is possible to vaccinate cattle, dogs and some other animals.
If you think you may be at risk of contracting leptospirosis from one of your animals, you may want to consider getting them vaccinated.