Swimmers and other watersports enthusiasts have been warned to avoid the Liffey river because of concern about bacterial disease infection.
Issued by the Eastern Regional Health Authority's director of public health, Dr Marie Laffoy, the warning comes days after the hospitalisation of three canoeists who were out on the Liffey between Lucan and the M50 flyover.
The three patients have since recovered and have been discharged from hospital.
The disease affects both humans and animals. In Ireland it is usually picked up from rats, although a milder form can be caught from cattle or dogs. The infection is spread through contact with rat, cattle or dog urine or cattle manure.
Leptospirosis is an occupational hazard for farmers, vets and sewage workers. It is a recreational hazard for campers or those who participate in outdoor sports in contaminated areas and has been associated in particular with water sports.
Speaking yesterday, Dr Laffoy said: "We are advising people to avoid swimming or boating in water which is obviously polluted, as well as ensuring they cover any cuts or abrasions with a waterproof dressing while swimming or canoeing."
Swimmers and boaters are also advised to shower thoroughly following any water activities.
People in contact with animals or contaminated clothing are also advised to wash their hands before eating, drinking or smoking.