Unprecedented flooding throughout low-lying portions of New York City over the past two days undoubtedly left hundreds—if not thousands—of rats scrambling for their dear lives. According to experts, most of them likely survived. “They’re a jack of all trades when it comes to locomotion,” says Rick Ostfeld of the Cary Institute of Ecosystem Studies in Millbrook, N.Y. “They can’t sprint, but they run well; they’re not Michael Phelps, but they’re strong swimmers; and even though they don’t have prehensile tails, they climb well. They do it all.”
Ostfeld notes that rats can easily swim a couple hundred yards. In fact, he says, “one of the ways that rats have dispersed around the world is by jumping off of ships and swimming to shore—the proverbial ‘rats leaving a sinking ship’ is actually based on reality.”
No one knows exactly how many rats live in New York City, but Ostfeld suspects that there are at least as many rats as humans. The city’s population is dominated by the Norway rat (Rattus norvegicus), an invader from Europe, and the Black rat (Rattus rattus), which originated in Asia. These highly resilient rats can be found throughout New York City, but they usually don’t travel far within those limits.
The displacement of rats caused by Hurricane Sandy—a dispersal of rats that is likely unprecedented for the city in terms of numbers—has Ostfeld concerned about a possible increased spread of rat-borne diseases. “You get infected individuals mixing with uninfected individuals and that’s a recipe for an outbreak,” says Ostfeld. “It spreads like the flu, from rat to rat.”
Urban rats are known to carry infectious diseases including leptospirosis, typhus, salmonella, hantavirus, and even the plague. The incubation period for these diseases in humans is usually a couple of weeks or months, and symptoms are often similar to those of a common flu. According to Ostfeld, “In the coming weeks and months, health-care providers should have rat-borne diseases on their radars and potentially test for them.”