A widely used, safe and cheap medication that is best known to Americans as a remedy for heartworm in dogs appears to thwart bedbug outbreaks. While more research is needed, the drug, ivermectin, could be a much easier and manageable way to fight bedbug outbreaks, which have soared in recent years.
Bedbugs are common in the tropics and were rare in North America until a few years ago. There aren't a lot of good surveys to show just how bad the problem is, but a 2009 study found that six percent of New York City residents reported bedbugs. In London, bedbug outbreaks are growing at a rate of about 25 percent per year. The resurgence is likely due to more international travel, the exchange of used furniture and a declining use of pesticides in houses, Dr. Johnathan Sheele, of Eastern Virginia Medical School, told Take Part.
"People are thinking about strategies," to eradicate bedbugs, he says. "But there aren't that many good oral medications for ectoparasites [parasites that live on the body] that are known to be safe and effective in humans."
Bedbug bites cause a rash that can last for weeks. Symptoms can be treated with antihistamines and steroids. But, the biggest problem is getting rid of the infestation in order to prevent more bites.
In the bedbug lifecycle, eggs are laid, attach to solid surfaces near a blood source and hatch in seven to 10 days. Nymphal-stage bugs feed on human blood, mostly at night. The blood meal is needed for continued development into adulthood.
Right now, the most common methods for treating an infestation are with pesticide sprays, steam cleaning, removing furniture and clutter in the infested areas, vacuuming and laundering. Professional extermination services are almost always needed, Sheele says.
"There aren't many good effective strategies at preventing and treating it," he says. "That's one of the reasons invermectin might be an option."
A new strategy is also sorely needed because bedbugs appear to be developing a resistance to the most common pesticides in use, he adds.
In a study presented Monday at the American Society of Tropical Medicine and Hygiene annual meeting, Sheele showed ivermectin may be a solution. One study he conducted found that bedbugs that fed on mice injected with ivermectin died at a rate of 86 percent. In another study, four brave human volunteers were given a dose of ivermectin and then were exposed to bedbugs. Within three hours, 63 percent of the bugs had died compared to 8 percent in a control group. The bugs continued to die 54 hours after the dose of ivermectin, but there wasn't 100 percent effectiveness.
The medicine appears hinders the ability of bedbugs to develop into adulthood, thus eventually ending the infestation, Sheele says.
Besides being used as a heartworm medicine for dogs, ivermectin is an important drug in much of the developing world. About 50 million people receive ivermectin each year to control River Blindness, a tropical disease caused by bites from black flies. It's safe and cheap.
"Ivermectin has been around for over 20 years," Sheele says. "It's effective against a wide range of human endo and ectoparasites." Ectoparasites include head lice, body lice and scabies.
The next step is to test the medication in an actual bedbug infestation, Sheele says. It's possible that ivermectin may be most effective if used along with extermination.
"Ivermectin is not going to be a silver bullet for all cases," he says. "I envision it for people in small outbreaks in a small space, like a bedroom. It might not be effective for an outbreak involving 10 people in an entire house."
The drug might also be a good strategy for someone staying in a hotel room that has a bedbug infestation in order to prevent carrying the bugs back home. People would likely have to take the medication for about two weeks.
Question: Would you use pesticides to rid your home of bedbugs or try another tactic? Tell us what you think in the comments.
Shari Roan is an award-winning health writer based in Southern California. She is the author of three books on health and science subjects.