long been held up as the chief villain in the spread of the Bubonic Plague; however, recent studies show that rats alone could not account for the rapid spread of the disease through Europe in the Middle Ages. Still, the Centers for Disease Control does list nearly a dozen diseases directly linked to rats. Most urban areas battle rat infestations. A 2015 study by the American Housing Survey (AHS) found that eighteen percent of homes in Philadelphia showed evidence of rodents. Boston, New York City, and Washington, D.C., also demonstrated significant rodent infestations. Indeed, rats in New York City are famous for their size and prevalence. The urban legend that the rat population in Manhattan equals that of its human population was definitively refuted by Robert Sullivan in his book Rats but illustrates New Yorkers' awareness of the presence, and on occasion boldness and cleverness, of the rodents. New York has specific regulations for eradicating rats; multifamily residences and commercial businesses must use a specially trained and licensed rat catcher. Chicago was declared the "rattiest city" in the US by the pest control company Orkin in 2020, for the sixth consecutive time. It's followed by Los Angeles, New York, Washington, DC, and San Francisco. To help combat the problem, a Chicago animal shelter has placed more than 1000 feral cats (sterilized and vaccinated) outside of homes and businesses since 2012, where they hunt and catch rats while also providing a deterrent simply by their presence. Rats have the ability to swim up sewer pipes into toilets. Rats will infest any area that provides shelter and easy access to sources of food and water, including under sinks, near garbage, and inside walls or cabinets. In the spread of disease Rats can serve as zoonotic vectors for certain pathogens and thus spread disease, such as bubonic plague, Lassa fever, leptospirosis, and Hantavirus infection. Researchers studying New York City wastewater have also cited rats as the potential source of "cryptic" SARS-CoV-2 lineages, due to unknown viral RNA fragments in sewage matching mutations previously shown to make SARS-CoV-2 more adept at rodent-based transmission. Rats are also associated with human dermatitis because they are frequently infested with blood feeding rodent mites such as the tropical rat mite (Ornithonyssus bacoti) and spiny rat mite (Laelaps echidnina), which will opportunistically bite and feed on humans, where the condition is known as rat mite dermatitis. As invasive species