After one British man reportedly contracted a rare and potentially fatal waterborne illness in Warleigh Weir in Bath, local swimmers are being told to take extra precautions before taking a dip. The culprit responsible is one of the most common and notoriously icky rodents around: rats.
Unseen bacteria lurking in the waters pose a threat at any given time of year, but the odds of people getting ill goes up in the summer months as more recreational swimmers head to nearby lakes, rivers, and streams to cool down. Of the bacteria present, one called Leptospira can lead to an infection called leptospirosis or, in its most severe form, Weil’s disease.
According to the National Health Service (NHS) in England, leptospirosis is spread via the urine of infected animals like rats. The bacteria enters through a person's eyes, mouth, or an open cut or scratch when they come into contact with infected soil or freshwater.

Public Health England reports there are around 50 to 60 cases of leptospirosis in England and Wales each year, or about one case per million people. Infection is rare, and most of the time results in a mild illness treated with simple antibiotics. However, consequences can be fatal if the disease develops into its secondary and more severe form. Symptoms typically occur between three and 21 days after being infected. The first phase includes flu-like symptoms, including fever, headache, vomiting, and sometimes a rash. If the infection reaches the Weil’s disease phase, those symptoms get more severe and similar to meningitis with jaundice, abdominal pain, diarrhea, kidney or liver failure, and even death from heart, liver, or respiratory failure.
Experts say the best way to avoid infection is to be aware of the water you’re coming into contact with. Bacteria are more likely to be present in slow-moving or stagnant waters, such as lakes and ponds, as well as areas near livestock or where rodents are present.
“Although leptospirosis is a rare infection in the UK, we encourage swimmers and athletes to take precautions when entering open water – including covering cuts with a waterproof plaster, wearing appropriate protective clothing, avoiding swallowing and/or splashing water into your mouth, and after swimming, cleaning your hands thoroughly,” Dr Smita Kapadia, consultant in communicable disease control at Public Health England East, told CambridgeshireLive.