Recent reports highlight an ordinary issue few care to think about: homegrown rats. According to ABC News, the number of rodents has begun to swell in cities throughout the nation, spurring federal disease specialists to seek a solution to this problem. Meanwhile, a recent study conducted by Columbia University scientists finds an atrocious number (and type) of viruses and bacteria in Manhattan’s rats. “This is a recipe for a public health nightmare,” Peter Daszak, president of EcoHealth Alliance, told The New York Times.

National Issue

The dominating rat species in urban centers throughout the country is Rattus norvegicus, often called the Norway rat, though also referred to as the brown, wharf, gray, sewer, barn, or house rat. Rats are first and foremost commensal animals who live alongside us, eating our food and leaving their droppings and urine markings for us to see. In Chicago, according to ABC, rat sightings increased from 22,431 in July 2000 to 33,134 in July 2014, while in Boston, complaints are up by 40 percent this year. Rat inspections increased throughout New York City in recent years, increasing by 18 percent last year. 

Though news reports suggest a surge in the rat population occurred in Brooklyn after Hurricane Sandy, data from the New York City Department of Health and Mental Hygiene suggest otherwise, according to Brooklyn Bureau. Nevertheless, scientists believe an uptick in global rodent numbers is around the corner, which should lead to an increase in the 35 diseases, as calculated by the Centers for Disease Control and Prevention, they commonly spread. Rats can spread disease, which may include leptospirosis, salmonellosis, rat-bite fever, murine typhus, and the plague, both directly and indirectly through their urine markings.

And so the nightmare begins. In a study published earlier this month, scientists used DNA analysis to examine 133 commensal Norway rats caught in the heart of New York City. Not only did the scientists discover the rats to be infected with bacterial pathogens known to cause acute or mild gastroenteritis in people, such as E. coli and C. difficile, they also found infectious agents, including Seoul hantavirus, linked to fever causing illnesses. Extending their search, the scientists identified 18 unknown species related to viruses that cause disease in humans. Most frightening of all, two of these new species, appeared to be similar to the hepatitis C virus.

While it's not entirely clear the rats can pass these new viruses, including Hep C, onto humans, generally speaking, it doesn't bode well. “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,” noted the authors in their conclusion.