Weil's disease (leptospirosis)

 Weil's disease is a form of a bacterial infection also known as Leptospirosis that is carried by animals, most commonly in rats and cattle.

What is it?

Weil's disease is a secondary phase of a form of a bacterial infection also known as Leptospirosis. Leptospirosis can infect almost any animal where it is harbored in the kidneys, but most commonly it is found in rats and cattle and is spread by their urine. It is not known to cause any noticeable illness in rats, so populations are unaffected by high levels of infection.

It is one of the most widespread zoonosis (disease spread from animals to humans) in the world, where it is most common in tropical and subtropical environments. Those who participate in water sports, come into contact with untreated water, and work in or near water are at a higher risk than others as it is most commonly passed to humans through water contaminated by rat urine.

Rats

Infection

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 floodwaters 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 freshwaters 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 saltwater, 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.

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