Rats

Disease-carrying fleas abound on New York City’s rats

In the first study of its kind since the 1920s, rats in New York City were found to carry a flea species capable of transmitting plague pathogens.

In research appearing March 2 in theĀ Journal of Medical Entomology, lead author Matthew Frye, an urban entomologist with Cornell University’s New York State Integrated Pest Management (IPM) Program, reported collecting more than 6,500 specimens of five well-known species of fleas, lice and mites from 133 rats. Among them: 500-plus Oriental rat fleas, notorious for their role in transmitting the bubonic plague, also known as the Black Death.

The Cornell and Columbia University research team looked most closely at the rat flea because of its potential as a vector for human diseases.

“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,” says Frye.

Where is the plague found these days? In the U.S., it’s found in the American Southwest among ground squirrels, prairie dogs and the fleas they harbor, infecting roughly 10 people each year. In other parts of the world, the incidence of plague is higher.

The plague wasn’t the only disease of concern. Co-author Cadhla Firth, a research scientist at Columbia University’s Center for Infection and Immunity, and her colleagues used molecular screening methods to look for two other pathogenic bacteria the Oriental rat flea could vector: Rickettsia (which they didn’t find) and several species of Bartonella.

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