NYC Reports Increases in Leptospirosis, an Infection Spread via Rat Urine

Rats in New York City are becoming more than a nuisance. The New York City Department of Health has released a health advisory after recording six cases of human leptospirosis, an infection with Leptospira bacteria that can be spread through rat urine. In 2023, the city recorded 24 cases, the highest number in a single year.

Leptospirosis typically presents with flu-like symptoms, including fever, headache, muscle aches, and chills. Other common symptoms include nausea, vomiting, diarrhea, jaundice, and reddened eyes. If not treated promptly, leptospirosis can progress to more severe complications, including kidney failure, liver damage, and respiratory distress.

The bacteria from infected rat urine can thrive in warm and moist environments for weeks. Humans can get infected if they come into direct contact with the urine or urine-contaminated water, soil, or food. The bacteria can enter through open wounds, eyes, nose, or mouth.

In New York City, some cases involved garbage collectors handling trash bags containing food waste. Drinking from or swimming in contaminated water sources could also cause infection. However, human-to-human transmission is rare.

“While the rat problems in many cities don’t get the attention as in NYC, rats can be found in urban areas throughout the country and carry the same risk of leptospirosis,” said Brian Labus, PhD, MPH, an assistant professor in epidemiology and biostatistics at the University of Nevada, Las Vegas.

Leptospirosis is the most prevalent in tropical climates. Excessive rain and warmer temperatures in New York City may have also helped the bacteria survive longer in environments.

How Is Leptospirosis Diagnosed and Treated?

Diagnosing leptospirosis can be challenging due to its nonspecific symptoms and the need for specialized laboratory tests, Labus explained.

PCR tests on blood and urine are available through commercial labs. The bacteria are present in the blood within the first four to six days of illness and in the urine around day seven and onward.

Leptospirosis can be treated with common antibiotics such as such as doxycycline or azithromycin. In severe cases, intravenous antibiotics may be necessary, Labus said.

How Can You Avoid Getting Leptospirosis?

Preventing leptospirosis begins with minimizing exposure to contaminated environments and practicing good hygiene. 

“While people generally avoid rats, they may not think about avoiding places where rats have been in the past,” Labus said.

“If you are cleaning areas where rats may have been, like around your trash cans, you should wear gloves and use a 10% bleach solution to kill the bacteria on surfaces that are potentially contaminated with rat urine,” he added. “Even something as simple as wearing shoes to take out the trash can help reduce your exposure.”

Additionally, maintaining clean living and working spaces, proper sanitation practices, and rodent control measures can help mitigate the spread of the disease within communities.

New York City has appointed a “rat czar” to oversee the city’s rodent control programs. These initiatives include using rat birth control, pumping carbon monoxide into rat burrows, and requiring all businesses to use trash cans with lids.

“There are many different options for rodent control, and taking a comprehensive approach to it will allow for a significant reduction in the rodent population and, ultimately, a reduction in diseases like leptospirosis,” Labus said.