Infection of humans usually occurs where open wounds are immersed in relatively stagnant water contaminated with rat or cattle urine. It can be contracted from contact with any fresh or untreated water including ponds, canals, lakes and rivers, as well as flood waters that are contaminated.
Those most at risk of infection are open water swimmers who expose their whole body to possible infection.
Activities that occur in or near fresh water such as fishing, water skiing, sailing and kayaking also present a risk.
Activities that can cause open wounds or that take place near the water's edge where rat urine is more likely to be found increase the risk of contracting the disease.
People who have previously had leptospirosis develop immunity to the particular strain that they were infected with and others closely related for up to ten years. They are not immune to other strains and may become infected again if continuing in activities where it is a risk.
It does not usually result from swallowing water or rat bites.
The bacteria are unable to survive in salt water, so there is no risk of infection of Weil's disease from swimming in the sea.
The risk of contracting the disease varies according to the size of the local rat population, which unfortunately is very hard to assess. Landowners, local authority environmental health departments, and in agricultural areas, Department for Environment, Food and Rural Affairs (DEFRA), may be able to provide assistance for operators who may need to assess the risk.
Symptoms can occur between 3 and 21 days from the time of infection. There can be two distinct phases of leptospirosis.
Symptoms are similar to those of the flu, including high fever, severe headache, chills, muscle aches, and vomiting, and may also include a rash.
May last between 3 to 5 days before recovery.
In mild cases the patient will recover after just the first phase but they can suffer fatigue and depression for some time afterwards.
Initial symptoms will reoccur.
Further symptoms can vary according to severity and may include jaundice (yellow skin and eyes), red eyes, abdominal pain, and diarrhoea.
Symptoms can be similar to those of meningitis.
Severe cases can also cause the failure of kidneys or liver.
Death can occur due to heart, liver or respiratory failure.
The best prevention is to understand where and how Weil's disease can be caught and taking precautions based on this knowledge. If you know you may come into contact with untreated water such as flood waters, canals, ponds and rivers you can reduce the risk of infection by taking the following precautions:
Cover any open wounds such as cuts and scratches with waterproof plasters.
Wear protective clothing such as gloves.
Wash thoroughly and as soon as possible if you have entered the water.
Assess the risk of the likelihood of contamination if contemplating entering fresh water, particularly be aware of stagnant water.
Carefully clean any open wounds obtained during time at fresh water.
Employers have a duty to employees to inform them about the risks of their work environment and to decrease the risk as far as is reasonably practicable. This includes PPE provision and policy implementation based on risk assessment.
Employees that work near water should be provided with a workers card that can be presented to their doctor if symptoms appear. This means they can be diagnosed and treated quickly, reducing the likelihood of severity of infection.
Seek medical treatment and explain to the practitioner that you have been in contact with open water. If you are an employee, show them your workers card. Early diagnosis and treatment of Leptospirosis can prevent more severe cases of infection.