Infected with 1.6 bacterial agents and 3.1 viruses, the average New York City rat is a cesspool of disease. But perhaps more frightening to hear is that they’re also host to “many more novel viruses” with unknown potential to harm city dwellers, according to a new study in the journal mBio.

“Our findings indicate that urban rats are reservoirs for a vast diversity of microbes that may affect human health and indicate a need for increased surveillance and awareness of the disease risks associated with urban rodent infestation,” says the study, which looked at samples of blood, urine and feces in 133 rats.