(Beyond Pesticides, November 16, 2012) New research suggests that the drug Stromectal (manufactured by Merck & Co.), which is typically used to treat parasitic worms, may also kill bed bugs. The active ingredient in the drug is ivermectin, which has also been getting publicity recently for its efficacy in killing head lice. Unfortunately, ivermectin, a member of the avermectin family of compounds, appears risky, and even unnecessary given that there are safe non-toxic methods to control and prevent bed bug and head lice infestations.
John Sheele, M.D., an emergency physician at Eastern Virginia Medical School in Norfolk who led the bed bug study, tested ivermectin on himself and three colleagues over the course of five different blood meals using three adult and three juvenile bed bugs. They allowed the bed bugs to feed on them before taking the drug and 3, 8, 22 and 54 hours after consuming the same combinations of different insecticides. Within three hours of feeding on blood containing ivermectin, the bed bugs began to die.
David Pariser, M.D., also of Eastern Virginia Medical School, led a different study that looked at the efficacy of using ivermectin applied topically to control head lice. Researchers found that after 14 days, a lotion with .5 percent ivermectin worked on 73.8 of the 141 volunteers, who were mostly children under the age of 12.
“Ivermectin is effective against a broad range of insects -body lice, head lice, scabies,” Dr. Sheele said in an interview with Bloomberg. “What I’d like to be able to do is a real-world experiment where we find people who have bed bugs, treat them with the regimen and see if it gets rid of their infestation.”
However, taking avermectin does come with risks. A number of adverse event reports related to its use, especially among the elderly, where deaths associated with ivermectin prompted a 1997 warning in the medical literature that it not be used at all. Side effects of ivermectin may include dizziness, loss of appetite, nausea vomiting, stomach pain, diarrhea, constipation, weakness, sleepiness, uncontrollable shaking and chest discomfort, among others.
Ivermectin and other avermectins are nerve poisons. They stimulate the gamma-aminobutyric acid (GABA) system, a chemical “transmitter” produced at nerve endings, which inhibits both nerve to nerve and nerve to muscle communication. The affected insect becomes paralyzed, stops feeding, and dies after a few days.
In addition to human health effects, the problem with introducing more chemicals to combat pests is that it’s only a matter of time before they are rendered ineffective through resistance. Bed bugs have slowly been developing resistance mechanisms and have become resistant to most, if not all, insecticides on the market. On average, insecticides labeled for bed bug control can take over 150 hours to kill a bed bug, compared to seconds or minutes in previous years. An Ohio State study, “Transcriptomics of the Bed Bug,” published January 2011 in the journal PLoS One, confirms bed bug resistance to pyrethroid insecticides and highlights the need to adopt non-chemical methods for controlling bed bugs and other insect pests.
Fortunately, the chemical treatments that are more harmful to humans than bed bugs or lice are also not actually necessary, as these pests can be effectively controlled with non-toxic approaches. An Integrative Pest Management (IPM) approach, which includes methods such as vacuuming, steaming, and exposing the bugs to high heat can control an infestation without dangerous side effects. This approach, as well as taking steps such as sealing cracks and crevices, reducing clutter and encasing mattresses can also help to prevent an infestation in the first place.
Head lice management involves the basic steps of education, prevention, monitoring, and control. Following these steps should prevent a serious infestation from occurring in your home or school. Simple precautions such as telling children not to share combs, hats, and blankets are a good start in preventing the spread of lice. If you do find lice, there are simple and safe ways to get rid of them. One effective procedure involves combing through oiled hair with a special nit comb (available at most pharmacies) and drowning any lice you find in soapy water. Learn more in our factsheet, Getting Nit Picky About Head Lice.
For more information, on bed bugs, see Beyond Pesticides’ Bed Bug webpage, which includes news updates and a detailed fact sheet discussing bed bugs, the problems with pesticide treatments, and alternative control methods.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.