What NYC Dog Owners Should Know About Leptospirosis

Alarm has grown among some New York City dog owners in recent days as reports have circulated about the risks to canine health posed by the city’s legions of rats.

In the Williamsburg section of Brooklyn, a corner of McCarren Park that is used as a dog run was temporarily shut for maintenance after rumors of an outbreak of leptospirosis, a bacterial disease spread by rat urine, lit up social media. The bacteria can fester in puddles and damp spots, and animals can become gravely ill if they contract the disease. It can also sicken humans.

Lincoln Restler, a councilman who represents the area, tweeted last week that his office had received reports that several dogs who had visited the park later died of the disease. The city Health Department said it could not confirm the reports, but said that it was working with the Parks Department to inspect for rat activity in the park. Local veterinarians are supposed to report positive cases of leptospirosis to the Health Department.

“I’m hopeful that the actions taken by the parks and health department will address the conditions we have at McCarren,” Mr. Restler said in an interview.

The accounts led to grave concern from dog owners, and reminders from local veterinarians about the importance of vaccinating dogs that spend a lot of time in parks.

What is leptospirosis?

The disease is caused by bacteria found in the urine of infected rodents and both humans and animals are susceptible to it.

The bacteria thrives in warm, wet environments, and can survive in soil, water and food. It can enter the body through open wounds or mucous membranes, or by drinking infected water.

The bacteria usually surges in the late summer and fall, said Dr. Gabrielle Fadl, a veterinarian at Bond Vet, a local chain. The initial symptoms are fairly nonspecific, including vomiting, fever and lethargy, making it tricky to diagnose an infection quickly.

Symptoms usually begin a week or two after exposure, and can be treated with antibiotics. If left untreated, leptospirosis can cause severe liver and kidney damage, and can be life-threatening.

How prevalent is the disease in New York City?

Reported cases of leptospirosis among people increased fairly dramatically last year, a spike that is believed to be linked to the spike in the rat population. At the same time, reported cases of canine leptospirosis actually dropped.

The city reported 15 cases among people last year, in contrast to an average of three cases a year for the previous 15 years. Health officials said that most cases “had a clear history or risk factor which exposed them to an environment with a severe rat infestation.” At least one of the people who was infected died. Human-to-human transmission is rare, and none of the cases was linked to a dog’s infection.

Among dogs, there were also 15 cases reported last year, down from a high of 29 in 2018. But health officials warned that the drop may be because providers failed to report cases as required. Between 2006 and 2020, a total of 269 cases — anywhere from eight to 29 cases per year — were reported to the Health Department from all five boroughs.

The federal Centers for Disease Control and Prevention notes…