Researchers found fleas carrying a flea species capable of transmitting the bubonic "black" plague on New York City rats.
The study that made the concerning finding was the first of its kind since the 1920s, Cornell University reported. Researchers collected 6,500 specimens of five species of fleas, lice and mites from 133 rats, and identified Oriental rat fleas among them; this flea species is believed to have been responsible for transmitting the devastating Black Death.
"If these rats carry fleas that could transmit the plague to people, then the pathogen itself is the only piece missing from the transmission cycle," said lead author Matthew Frye, an urban entomologist with Cornell University's New York State Integrated Pest Management (IPM) Program.
The bubonic plague is generally found in the American Southwest among ground squirrels, prairie dogs, but infects only about 10 people in the U.S. per year; in other parts of the world the incidence rate is much higher.
The plague wasn't the only concerning disease of concern observed on the rats; the researchers also found several species of Bartonella pathogens, which can cause severe clinical symptoms in humans, as well as other diseases. The findings suggest public health officials should work to monitor city rats and their parasitic fleas. NYC residents can also do their part by taking measures to keep rats at bay.
"Removing food and water and preventing access to shelter are key to knocking back rodent infestations," Frye said.
Once the rats are gone from an area that doesn't necessarily mean the threat of infection has been eliminated. The rodents can leave behind fleas, lice, and mites that require thorough sanitation to remove.
"It's not that these parasites can infest our bodies," Frye said, "but they can feed on us while seeking other rats to infest."
The findings were published in a recent edition of the Journal of Medical Entomology.
