NYC Health Alert: Surge in Illnesses Linked to Rat Urine Exposure

The New York City Department of Health and Mental Hygiene is warning healthcare providers to be on the lookout for human leptospirosis — a potentially deadly infection often caused by exposure to rat urine — amid an uptick in reported cases.

The number of reported cases of leptospirosis skyrocketed to 24 in 2023, up from an average of 15 per year from 2021 to 2023, compared to just 3 per year from 2001 to 2020. There have been six reported cases so far in 2024, health officials said in an alert last week.

Leptospirosis can be caused by several species of Leptospira bacteria found in the urine of any infected animal, but health officials said that in New York City, the infections are primarily caused by Leptospira interrorgans, which is associated with the Norway rat found in the city.

Among 98 cases reported between 2001 and 2023, the median patient age was 50 years, 94% of patients were male, and cases were most common in the Bronx, followed by Brooklyn, Manhattan, Queens and Staten Island.

Some cases presented with acute kidney and liver failure, and "occasionally" severe pulmonary symptoms. There were six deaths, health officials said.

Symptoms may include fever, headache, chills, muscle aches, vomiting, diarrhea, cough, conjunctival suffusion, jaundice and rash. Without treatment, kidney failure, meningitis, liver damage and respiratory distress can occur.

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Health officials are warning healthcare professionals to consider leptospirosis in any patient presenting compatible symptoms, "especially when there is evidence of acute renal and hepatic failure."

TMX contributed to this report.