Bedbugs Could Spread Nasty Chagas Parasite
Thu, 28 May 2015, 05:04 AM by Lee Shearer
Some new medical research gives some added urgency to a once-common admonition of mothers: Don’t let the bedbugs bite.
The little blood-sucking insects are capable of transmitting Chagas disease, University of Pennsylvania School of Medicine researcher Michael Levy told ecologists meeting in Athens’ Classic Center Wednesday.
But whether they could ever become an important vector for transmitting the tropical disease remains to be seen. Levy was addressing fellow scientists at the annual Ecology and Evolution of Infectious Disease conference, a gathering of ecologists, medical researchers and others interested in connections between infectious disease ecology and other fields.
Little-known in North America, Chagas disease is caused by a parasite called Trypanosoma cruzi, and transmitted mainly by a kind of insect called triatominae, or kissing bugs. Kissing bugs suck blood, like bedbugs, but that’s not precisely how they pass on the T. cruzi parasite. That happens when they defecate on skin after feeding; a person who scratches the itchy little wound may rub the kissing bug feces into the wound, along with the parasites in the feces.
The disease affects millions of people in Central and South America. Tens of thousands of people in the United States may be infected — but most people who have the disease don’t know they are infected, said Levy, a professor in the University of Pennsylvania’s Perelman School of Medicine.
Most infected people don’t have symptoms beyond early infection, but a large minority develop more serious symptoms 10 to 30 years later — symptoms which can include enlarged heart ventricles and heart failure. The long lag makes it hard to keep track of the disease’s spread.
Levy and fellow researchers did experiments to see if mice infected with T. cruzi could pass the parasites on to bedbugs, and if bedbugs could in turn transmit the parasite to mice. In both cases, the answer was yes.
That’s potentially a serious issue Levy said, because of the widespread distribution of bedbugs nowadays. The creatures were nearly eliminated by the use of the pesticide DDT, now banned in the United States, but in the past couple of decades they’ve made a big comeback.
When researchers surveyed one Philadelphia census tract, about 11 percent said they had bedbug infections in their homes, said Levy.
Levy and his fellow researchers added a couple of other worrisome observations when they wrote about their experiments recently in the American Journal of Tropical Medicine and Hygiene.
There are kissing bugs infected with T. cruzi in the United States, but for the most part they’ve been kept outdoors — but bedbugs are now seemingly everywhere.
And not only are bedbugs making a big comeback, new populations are showing resistance to the pesticides historically used to eliminate them, they wrote.
And treating houses for bedbugs is expensive — around $1,200, far more expensive than treating a house for kissing bugs, he said.
Researchers have still more questions to answer, Levy said.
“We have no idea what bedbugs feed on in the field,” he said — do they feed on mice or dogs, for example?
And ultimately, they hope to have a better idea of just how serious a risk bedbugs pose of transmitting T.cruzi and Chagas disease, he said.
A session on Ebolas virus dynamics and control closes out the conference on Friday.