Leptospirosis is caused by infection with Leptospira germs (bacteria). The infection passes from animals (commonly rats, cattle, pigs and dogs) to humans. In most cases, leptospirosis causes a mild illness. But, in some people, a more severe illness occurs. This more severe form is commonly referred to as Weil's disease. The main treatment for leptospirosis is antibiotics and most people make a full recovery.
What is leptospirosis?
Leptospirosis is caused by infection with the germs (bacteria) Leptospira. It is a type of zoonosis infection (an infection that can be passed from animals to humans).
In the majority of cases, leptospirosis causes a mild illness but, in some people, a more severe form of leptospirosis occurs. This more severe form is commonly referred to as Weil's disease, so called after Dr Adolf Weil who first described it.
How is leptospirosis spread?
Both wild and domestic animals can become infected with Leptospira, including rats, cattle, pigs and dogs. The germs (bacteria) can live for many years within the animal's kidneys and can be passed out in their urine into water, soil, vegetation and mud, where they can survive for several months. Often, infected animals show no outward signs of illness.
Leptospirosis can be passed on to humans through direct contact with the bodily fluids or tissues of an infected animal (such as urine) or through contact with soil or water contaminated with infected urine. The bacteria usually get into the human body through a cut or small abrasion in the skin. They can also pass through mucous membranes such as the skin that lines the mouth, the nose and the front of the eye. The bacteria may also be inhaled and enter the body via the lungs. Once inside the body, Leptospira have the ability to pass via the bloodstream and the lymph system to the internal organs.
How common is leptospirosis and who gets it?
Animals in countries all over the world carry Leptospira germs (bacteria) but the infection is more common in tropical areas with warmer climates. In the UK, leptospirosis is not very common. Public Health England reports that there are around 50 to 60 cases in England and Wales each year. That is about one case per million people per year.
The risk of developing leptospirosis is greater in certain groups of people - for example, those whose work involves exposure to animals, such as farmers, vets, abattoir workers and rodent control workers. Sewage workers also have an increased risk of infection. So do people who take part in water sports such as rafting, diving, fishing, canoeing, potholing or hiking through water. Leptospirosis has also been reported after episodes of flooding.
Leptospirosis symptoms in humans
As mentioned above, there are two forms of leptospirosis:
- A mild form causing a flu-like illness.
- A more severe form (Weil's disease) which can cause yellowing of the whites of the eyes or the skin (jaundice) and liver and kidney failure.
Around 9 out of 10 people just develop the mild form of the illness. The remaining 1 in 10 people develop Weil's disease. It is not clear why Weil's disease only develops in some people.
Symptoms of leptospirosis are first noticed at some time between 2 and 30 days after exposure to the germs (bacteria). However, they most usually develop after around 7 to 14 days. Some people with mild leptospirosis may develop no symptoms at all.
In both the mild and the severe forms of leptospirosis, flu-like symptoms develop first. They tend to last for between 5 and 7 days and can include:
- High temperature (fever) and chills.
- Feeling sick (nausea), loss of appetite, being sick (vomiting) and diarrhoea.
- Conjunctivitis. This is inflammation of the conjunctiva - the skin that covers the front of the eye and inside the eyelids.
- Joint and muscle pains (particularly in the calves and lower back).
- Feeling tired.
During this stage of the illness, the bacteria are spreading throughout the body via the bloodstream. The majority of people then recover as their immune system clears the infection. However, in some people, about a week after the flu-like symptoms have passed, a second stage of the illness then develops (Weil's disease). Symptoms of this second stage can include:
- Tummy (abdominal) pain
- Skin rash
- Muscle pains
During this second stage, bacteria begin to infect the organs of the body, such as the kidneys, the liver, the brain, the eyes, the heart and the lungs. Different organs may be infected in different people. However, commonly the kidneys and the liver are affected and kidney or liver failure can occur.
The lungs may also become involved causing symptoms such as cough, shortness of breath and bleeding within the lungs (which can lead to coughing up of blood). Some people develop symptoms similar to meningitis. Meningitis is an inflammation of the lining that covers the brain and spinal cord (the meninges). The heart may be affected in others, leading to inflammation of the heart muscle (myocarditis) and sometimes heart failure.
In the early stages of leptospirosis, it may be quite difficult to tell the symptoms apart from the flu. If you know that you have been in contact with water that was possibly contaminated with animal urine, or if you work with animals, you should tell your doctor and this can help to alert them to the possibility of leptospirosis.
Tests are usually carried out to confirm the diagnosis. You may be asked to provide a urine sample to look for Leptospira in your urine. Blood testing can also confirm the diagnosis by looking for evidence of the germs (bacteria) in your bloodstream.
Other tests may also be done to assess the severity of your illness. For example, blood tests to look for anaemia, to look at the clotting of your blood and to look at how your kidneys and liver are functioning. A chest X-ray may be done to look for lung problems.
What is the treatment for leptospirosis?
Antibiotics are the main treatment. The antibiotics most frequently used are a penicillin antibiotic (amoxicillin or ampicillin) or doxycycline. Antibiotics are usually prescribed as soon as possible after leptospirosis is diagnosed. In mild leptospirosis, antibiotic tablets may be all that is needed. In more severe cases, antibiotics given into your veins (intravenous antibiotics) are used.
People with mild leptospirosis may be treated at home. Those with the severe form of infection are usually admitted to hospital for treatment and monitoring.
Other supportive treatment may be needed - for example:
- Painkillers to help with muscle and joint pains.
- Medication, such as paracetamol, to help bring down high temperature (fever).
If you are unable to drink plenty of fluids, in order to avoid lack of fluid in the body (dehydration) you may need to be given fluids intravenously. In severe cases, close monitoring of the heart, help with breathing, or kidney dialysis may be needed.
What is the outlook?
As discussed above, 9 out of 10 people have a mild form of leptospirosis and the outlook (prognosis) in such cases is very good. Most people recover fully within two to six weeks but some may take up to three months to get better.
In more severe cases (Weil's disease), the outlook depends on which organs of the body are involved and to what extent. A few people each year in England and Wales die from leptospirosis. Death is usually due to internal bleeding, kidney complications or lung complications.
Can leptospirosis be prevented?
The best way to prevent leptospirosis is to avoid contact with potentially infected animals and potentially contaminated soil and water. You should avoid swimming or entering water that might be contaminated with animal urine.
Those working with animals that could be infected should wear protective clothing and equipment including gloves, eye protection and footwear. They should also pay strict attention to hygiene, including meticulous handwashing after exposure to animals. Rodent control can also help to prevent infection - for example, rubbish disposal and ensuring that rodents cannot get into buildings.
If there is contact with fresh, surface waters (for example, canals, ponds or rivers, or with rats) then you should:
- Cover any cuts, scratches or sores with a waterproof plaster. Thoroughly clean any cuts or abrasions that you may have got during the water activity.
- Wear protective clothing such as dry suits, gloves or protective footwear.
- Wash or shower as soon as possible after water sports.
- Avoid capsize drill or rolling in stagnant or slow-moving water.
- Wear thick gloves when handling rats.
- Wash your hands after handling any animal, and before eating.
For those at very high risk of leptospirosis for a short period of time, the antibiotic doxycycline may be prescribed to reduce the chance of developing infection.
Vaccination of some animals is carried out to help to control the infection. No human vaccine against leptospirosis is currently available in the UK.
Further reading and references
Leptospirosis; Public Health England
Haake DA, Levett PN; Leptospirosis in humans. Curr Top Microbiol Immunol. 2015387:65-97. doi: 10.1007/978-3-662-45059-8_5.
Musso D, La Scola B; Laboratory diagnosis of leptospirosis: a challenge. J Microbiol Immunol Infect. 2013 Aug46(4):245-52. doi: 10.1016/j.jmii.2013.03.001. Epub 2013 Apr 29.
Brett-Major DM, Coldren R; Antibiotics for leptospirosis. Cochrane Database Syst Rev. 2012 Feb 152:CD008264. doi: 10.1002/14651858.CD008264.pub2.
Brett-Major DM, Lipnick RJ; Antibiotic prophylaxis for leptospirosis. Cochrane Database Syst Rev. 2009 Jul 8(3):CD007342.
Charan J, Saxena D, Mulla S, et al; Antibiotics for the treatment of leptospirosis: systematic review and meta-analysis of controlled trials. Int J Prev Med. 2013 May4(5):501-10.