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Record Spike in Life-Threatening Infections from Rat Urine in New York City

A record number of individuals in New York City fell ill with a severe bacterial infection transmitted through rat urine last year, and this year is poised to reach another unprecedented level, according to the NYC Department of Health and Mental Hygiene.

The infection, known as leptospirosis, can manifest a variety of symptoms, including common ones like fever, headache, chills, muscle aches, vomiting, diarrhea, and cough. If untreated, it can progress to severe stages, leading to kidney failure, liver damage, jaundice, hemorrhage, respiratory distress, and potentially death.

The culprit behind this infection is the spirochete bacteria belonging to the genus Leptospira, primarily carried by rats that excrete the bacteria in their urine. Transmission occurs through direct contact with the bacteria via open wounds or mucous membranes.

New York City has been grappling with its rat population for a considerable time, with Mayor Eric Adams making rat control a significant focus. Recently, the city council proposed a new approach to diminish the rat population using salty pellets.

Although leptospirosis wasn’t a major concern stemming from rat activities in the past, the situation shifted notably during the pandemic when the rat population surged. The average cases spiked from three annually between 2001 and 2020 to 15 from 2021 to 2022. In 2023, a record-high of 24 cases was reported, with six cases documented as of April 10.

The rise in cases is attributed to the favorable conditions for Leptospira bacteria, which thrive in warm, moist environments. The NYC health department highlighted climate change as a contributing factor, with excessive rainfall and unusually warm temperatures creating ideal circumstances for the bacteria.

Clinicians were advised to remain vigilant for leptospirosis cases, which are typically treated with oral antibiotics for mild cases and intravenous antibiotics for severe ones. Symptoms usually appear within 5 to 14 days post-exposure but can manifest anywhere from 2 to 30 days.

Out of the 98 locally acquired cases recorded by the city between 2001 and 2023, the majority affected men (94 percent) with a median age of 50, ranging from 20 to 80 years. The Bronx reported the highest number of cases (37), followed by Manhattan (28), Brooklyn (19), Queens (10), and Staten Island (4). Most cases involved acute kidney and liver failure, with occasional severe respiratory complications, resulting in six fatalities.

These cases are typically associated with living or working environments contaminated with rat urine, soil, water, or items frequently exposed to rat urine such as trash bags or food waste bins. Human-to-human transmission is rare, as noted by the health department.

Apart from New York City, other regions have also faced leptospirosis cases. In the Netherlands, doctors reported a case of an 18-year-old who contracted leptospirosis after falling into a canal likely contaminated with rodent urine, presenting symptoms like jaundice and bloody eyes.