Last year, New York City saw 24 cases of human leptospirosis — the highest number in a single year. Six cases have been reported so far this year, the city's department of health and mental hygiene said in an April 12 health advisory.
Human infections are largely associated with exposure to rat urine and can lead to kidney failure or liver damage if left untreated, city health officials said. Leptospirosis is caused by several species of bacteria, which infected animals excrete in their urine. Transmission occurs through direct contact with infectious urine or contaminated water, soil or food. It can also enter the body through open wounds or mucous membranes.
Person-to-person transmission of the disease is rare, with most of the locally acquired cases in New York City linked to people who have a residential or occupational exposure, such as handling contaminated trash bags or food waste bins.
While leptospira bacteria are fragile and can die off quickly in dry heat or freezing temperatures, health officials said excessive rain and unseasonably warm temperatures "may support the persistence of leptospires in more temperate areas like NYC."
Clinicians should consider leptospirosis in any patient presenting with a range of flu-like symptoms — including fever, headache and chills, as well as red eyes and jaundice — especially when there is evidence of acute renal and hepatic failure, the health advisory said.
There were just 57 leptospirosis cases in New York City between 2006 and 2020.