The Rats of New York City Carry More Diseases Than Expected

New York City is known for its rats. They can be found in subways, skirting trash bags and skirting building corners. Now, though, scientists have taken a closer look at these rats and have identified bacterial pathogens that these rats may be carrying.

"New Yorkers are constantly exposed to rats and the pathogens they carry, perhaps more than any other animal," said Cadhla Firth, one of the researchers, in a news release. "Despite this, we know very little about the impact they have on human health."

In order to better understand the diseases these mammals carry, the scientists trapped 133 Norway rats at five sites in New York City. They specifically focused on rats trapped inside residential buildings. Targeted molecular assays confirmed the presence of 15 of the 20 bacterial and protozoan pathogens that the scientists looked for in addition to one virus, Seoul hantavirus.

That's not all the researchers found, though. High throughput screening methods identified 18 novel viruses, as well. These included two rate hepaciviruses, called NrHV-1 and NrHV-2. Although these are not the closest relatives to human hepatitis C, the identification of these viruses may be important to future medical research. The two viruses replicate naturally in the animal's liver, which suggests that their lifecycle is similar to the human hepatitis C virus. This is especially important when it comes to studying hepatitis C.

That said, what this study truly highlights is the importance of monitoring the New York rat population. In addition, it's crucial to study how the animals and the microbes that they carry could be transferred and make us sick.

"Rats are sentinels for human disease," said W. Ian Lipkin, one of the researchers. "They're all over the city; uptown, downtown, underground. Everywhere they go, they collect microbes and amplify them. And because these animals live close to people, there is ample opportunity for exchange."

The findings are published in the journal mBio.