New York reports a record 15 cases of a rare disease linked to rat urine in 2021, as vermin complaints flood in

• New York has recorded 15 cases of leptospirosis, and one death, in 2021. The rare disease comes from exposure to rats.
• Three of the people infected were experiencing homelessness.

Rats have been terrorizing New Yorkers even more than usual this year, teaming up in clan warfare during the food-scarce days of strict Covid lockdowns and harassing sidewalk diners once the city began opening up.

And this year, more New Yorkers have been falling seriously ill from a rare but potentially fatal bacterial disease called leptospirosis, which is spread through exposure to rats, and specifically through contact with rat urine or contaminated water.

Last month, the city's health department reported 14 cases of leptospirosis - an unusually high number since just New York has documented a total of 57 cases in the 15 years since 2006 - and alerted healthcare providers to be on the lookout for symptoms. Of the first 14 cases, 13 people were hospitalized with acute renal and hepatic failure, and one person died as a result of an infection, the alert said.

Last week, there was a 15th case. That person appears to have recovered, the health department told Insider.

The disease is treatable with antibiotics and some people won't experience any symptoms, though one in ten cases progress to severe complications, according to the Centers for Disease Control. Every year, there are roughly 150 cases of nationwide, according to the CDC, with most cases occurring in Puerto Rico and Hawaii.

The last time leptospirosis made news in New York was in 2017, when a cluster in the Bronx landed three people in the emergency room - sparking a wave of media coverage and criticism of the city's rat mitigation efforts. A 46-year-old man who worked in a meat processing facility had been hospitalized for muscle pain and shortness of breath after cutting his hand at work. He eventually developed the first documented case of testicular swelling associated with leptospirosis.

The two others lived or worked on the same block where the first man worked. Of the three, two recovered and one person died, the city said at the time.

A few months later, New York issued a veterinary medical alert when dogs started falling ill, some of which were believed to have slurped contaminated water in standing puddles while taking walks during the unusually warm winter.

There are about 16 cases of canine leptospirosis a year in New York, according to a surveillance report. Canine cases do not predict where human cases will occur, and while canine to human transmission is possible, no case has ever been documented in New York.

Climate change, homelessness

The 15 cases of leptospirosis reported this year came from all over the city. The city's health department says it can't say for certain what's behind the higher number of cases.

Climate change is a likely driver, since warm, moist environments contribute to higher rates of leptospirosis. "Changes in climate that allow bacteria to persist could contribute to an increase in human cases," a health department spokesperson told Insider this week.

The spokesperson said that none of the leptospirosis cases had been traced to the widespread flooding in September from Hurricane Ida. Similarly, no infections had been linked to Hurricane Sandy in 2012.

Housing insecurity also puts people at greater risk of coming in close contact with rats and contaminated water. Three of the people infected this year were experiencing homelessness, and all of the local infections recorded in the health department's database since the year 2000 involved a person who was experiencing poverty.

Dr. Robert Glatter, a physician at Lenox Hill Hospital in New York, said leptospirosis frequently goes undiagnosed because it affects vulnerable populations who often can't access healthcare.

"The main issue for practicing physicians in big cities is to know about the disease, and then consider it in patients presenting with certain risk factors such as poverty or homelessness," he said in an email.

A task for Sisyphus

Brown rats, sometimes known as Norwegian rats, have been a fixture of New York City since they began arriving on boats from Western Europe in the 1700s. In 2014, statistician Jonathan Auerbach estimated that there were about 2 million rats in New York, which is about a quarter the size of the city's human population.

There's no reliable headcount of New York City rats and how many of them carry the disease. Dr. Ian Lipkin, a Columbia University epidemiologist who co-authored a 2014 study on pathogens, including the bacteria that cause leptospirosis, in New York rats, said that the best thing the city can do is invest in rodent control.

The city spends millions of dollars a year getting rid of rats. There's even a regular "Rat Academy," which is aimed at turning community members into soldiers in the war on rats. (It will be held virtually this year, starting Oct. 21, and you can register here.)

But as Joseph Lhota, who was known as the city's "rat czar" in the 1990s, put it once: "Anybody who's in charge of eradicating rats in New York knows exactly what Sisyphus felt like."

Just a few months after the 2017 outbreak in the Bronx, New York Mayor Bill de Blasio demanded "more rat corpses" and announced a $32 million anti-rat plan on top of the city's regular sanitation budget. This included $8.8 million for new trash compactors and another $16.3 million to put down concrete "rat pads" over the dirt, basement floors at the city's public housing units with the worst rat issues.

But then came Covid. While it appears that the widespread closures of restaurants and bars in March of 2020 helped to depress the number of rats scampering through the city, New York's vermin population appears to have more than recovered, says Dr. Robert Corrigan, a New York urban rodentologist who has guided several mayors on their anti-rat initiatives.

Rat complaints to New York's 311 hotline dipped down during 2020, the first year of the pandemic, and have increased by 20% so far in 2021, for a total of almost 20,000 complaints.

That coincided with a $45.6 million sanitation department budget cut, which reduced trash pick up around the city, including a 25 percent reduction in the areas identified by de Blasio's plan for rat mitigation.

Last week, a resident from Mariana Bracetti Plaza in the East Village - one of the developments included in de Blasio's anti-rat plan - posted a video to Instagram that went viral. In it, rats were plundering the pile of trash outside her window so voraciously that it woke her up.

A spokesperson for the New York Housing Authority said that inspectors had responded to the infestation and that no recent leptospirosis infections had been reported at its properties.

A Batman for New York's rat-averse

Richard Reynolds knows all too well the problem of rats repeatedly returning to a pile of garbage.

Reynolds leads a double-life: By day, he's an American Kennel Club certified dog show judge. By night, he runs a volunteer group of rat-hunting dog-owners, becoming a version of Batman responding to calls from desperate city residents. He gets complaints from public housing projects "constantly," often to the same trash cans.

Most Friday nights, for over thirty years, he makes the trip into New York from his home in New Jersey to lead rat-hunting trips with his terriers.

The resulting spectacle is not for the squeamish, as fresh blood streams from the dogs' mouths and maggot-infested rat carcasses are dragged out into the open.

Reynolds says he's never had a dog get sick as long as he's been hunting rats.

"You can tell when you see a pile of dead rats if they look sick and dehydrated, they probably have lepto," Reynolds said. "Our dogs walk right past those rats."

Like others, Reynolds is well aware that ridding New York City of rats is an uphill battle.

"If you have two rats today, you'll have 24,000 rats a year from now if there's enough trash for them to eat," he said.