City dwellers across the U.S. might agree on one common enemy: bed bugs. But hey, not to worry, right? "Bed bugs are not known to spread diseases, but bites can be very itchy and irritating." Or so says the New York City Department of Health. But that assertion may not be true. Because a new study suggests bed bugs could be capable of spreading infection… specifically, by passing on the parasite that causes Chagas disease.

Chagas can cause anything from mild headaches to eventual heart failure. The condition is usually spread by what’s called the kissing bug—a relative of bedbugs, which also feeds on blood. But it doesn't pass the parasite through its saliva, as happens with malaria, for example. 

"You get it when the bug bites you and then defecates on you. The parasite is in the feces of the bug." Michael Levy, a disease ecologist at the University of Pennsylvania. Levy says scratching the bite then works the parasite into the skin, infecting the victim.

Levy and his colleagues wanted to see if the same thing could happen with bed bugs. So they let em loose on mice that carried the Tripanosoma cruzi parasite. The bugs caught it—and were then able to transmit the parasite back to mice. With one caveat—some mice actually hunted and ate the bugs—a sure route for infection. "People don't eat bed bugs, so we're not really at risk of being infected through the oral route by bed bugs." That said, one mouse actually did catch the disease not by snacking, but through a bedbug bite—more analogous to the way a human might. The study is in the American Journal of Tropical Medicine and Hygiene. [Renzo Salazar et al: Bed Bugs (Cimex lectularius) as Vectors of Trypanosoma cruzi]

Any advice for the bed bug–phobic? "Don't panic. It's important to remember that bed bugs may be able to carry the disease, but they don't cause it." Meaning, you'd need to live with someone with Chagas disease, who can pass the parasite to a bed bug, and then actually catch it from that bug. Still, Levy says, bugs pave the way for pathogens to spread. "It's very dangerous to let bugs that feed on human blood get out of control, like unfortunately has happened in the United States and across the world with bed bugs." Maybe it's time to treat bed bugs like a public health issue, Levy says, rather than just a pest.

—Christopher Intagliata

[The above text is a transcript of this podcast.]