Bed Bugs Can Transmit the Chagas Disease Parasite

The parasite is usually associated with Latin and South America, but was recently found throughout Louisiana, too

A bed bug surrounded by potentially parasite-laden feces. Photo: Penn Medicine/Robert Press

Having insects crawl all over your face and body and bite you while you sleep is a nightmare. For anyone with bedbugs, it's also a reality. It's bad enough to provide a nocturnal meal to a six-legged blood sucker. But for many, that experience delivers even more than phobia: it could be deadly.

We already know that some night-time creepers, including mosquitoes and kissing bugs, can transmit life-threatening maladies like malaria or Chagas disease. But still others, researchers found, while not natural vectors of disease, can be trasmitters, if given the chance. Bed bugs—normally just disgust-inducing pests—can becomes a bedroom-dwelling army of disease carriers when they acquire and transmit Trypanosoma cruzi, the parasite that causes Chagas disease. Those were the findings of a new paper published in American Journal of Tropical Medicine and Hygiene

Chagas disease is a top killer in Central and South America, and until now, its parasite was only known to be carried by kissing bugs. These bugs creep into a person's bed at night, often biting them around the mouth (hence their name).

While enjoying its meal, the kissing bug will often defecate. Later, the bite begins to itch, and the person might scratch or rub it in her sleep, smearing the potentially parasite-teeming poop into the wound. If T. cruzi parasites are present, she might develop Chagas disease, which usually kills its victims years later through sudden heart disease or digestive failure. 

Kissing bugs, however, have another blood-loving, bedroom-creeping cousin: the bed bug. Given the recent uptick of bed bug infestations, researchers from the University of Pennsylvania and the Universidad Peruana Cayetano Heredia in Peru wondered if bed bugs might be similar enough to their deadly cousins to also transmit the disease. (Some decades-old past studies also investigated this question, but they focused on mice that ate bed bugs, not bed bugs that feasted on mammals.)

In laboratory experiments, the researchers allowed 3,000 bedbugs to feast on T. cruzi-infected mice. After a month, the majority of the bed bugs turned up positive for T. cruzi—which was not shy about taking up residence in a new species' gut. As one of the researchers commented in a release: "I've never seen so many parasites in an insect."

Next, the researchers allowed those infected bed bugs to feed on uninfected mice. After another month, nine out of 12 of the mice had developed an infection themselves. Finally, they found that mice can develop the disease when they have a small open wound that comes into contact with infected bed bug feces. (Bed bugs, by the way, also defecate while they feed.)

The researchers' next step is to try and find out whether or not some bed bugs in the wild (i.e., our homes) are already infected with T. cruzi, and if not, how likely this scenario is to come to pass. Unfortunately, this is something that actually could happen, they point out. An estimated 300,000 people in the U.S. are now positive for Chagas disease, and the T. cruzi parasite can also live in pets.

And, researchers from Loyola University New Orleans recently found that, of 49 kissing bugs collected from around Louisiana, 40 percent were positive for T. cruzi. Tree frogs were the most common meal for those bugs, but humans were second. The problem will probably only worsen in the future: Some studies predict that the kissing bug's range in the U.S. will expand as the climate warms. 

So between kissing bugs, bed bugs and climate change, the U.S. might be poised to become a lot more familiar with Chagas disease than it has been in the past. As the bed bug authors note, bed bugs "are already here—in our homes, in our beds and in high numbers. What we found has thrown a wrench in the way I think about transmission, and where Chagas disease could emerge next."

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