Although the drug Ivermectin has treated millions of people in the developing world throughout the past 20 years, little was known about how it actually worked — until now.
In a collaboration between two old friends at MSU and McGill University in Quebec, Canada, research has brought to light the way Ivermectin works to eliminate filarial parasitic worms in humans.
Filarial worms are thread-like parasites that live in body and blood tissues in their human hosts.
It’s a breakthrough that could lead to the development of new medicines and could shorten the length of treatment for the diseases Ivermectin treats, said Charles Mackenzie, an MSU professor in veterinary pathology.
“Mackenzie and I first met in 1983 when I was on staff at Michigan State,” said Tim Geary, the director of the Institute of Parasitology at McGill University and Mackenzie’s primary research partner.
“We were questioning the way the drug worked and decided we wanted to look into it. This is a collaboration of 35 years. We were finally able to get together to do the research to answer that question.”
Mackenzie and Geary’s research found that Ivermectin works not by killing worms inside the body, but rather by shutting down worms’ ability to produce secretions and proteins that turn off a human’s immune system, Mackenzie said.
The research, which has been published in the most recent edition of the Proceedings of the National Academy of Sciences, showed shutting off the immune system prevents the body from killing the worms, he said. Similar drugs are used to treat heartworm in dogs, Geary said.
“Resistance (to the drug) may be happening but if we understand the mechanism by which resistance is developing we can find new drugs that work in different way,” Mackenzie said.
“This is certainly one of the most successful drugs in the tropical world, and it’s changed tropical medicine. Not understanding how it worked was not a problem, but rather a gap in an important issue.”
Developed by pharmaceutical company Merck and Co., more than 2.5 billion tablets of Ivermectin have been donated by the company since 1987.
The World Health Organization recently published a study showing for the first time in history, elimination of diseases Ivermectin treats, such as river blindness, are on their way to eradication.
The drug has been effective in impoverished African communities because it’s easy and safe to administer to communities, said Terrie Taylor, a professor of internal medicine.
“These diseases are rarely fatal, but they compromise the quality of life significantly,” Taylor said.
“This often creates a stigma so people with the diseases are ostracized.”
River blindness, which causes severe itching and can progress to actual blindness, and elephantiasis, which causes extreme swelling and infection of different body parts, are two of the primary diseases treated with Ivermectin, Taylor said.
The development is exciting because investment in the field is rare, Geary said.
“These are diseases of poor people,” he said. “There is relatively little investment in developing or understanding these conditions.”
Yovany Moreno, a graduate student at McGill University, also was critical to the research breakthrough, Mackenzie said.
Although the research doesn’t have the capacity to change treatment immediately, Geary said it’s an important basis for understanding the relationship between the medicine and the parasites.
“In poor countries it’s really hard to sustain public health efforts like the treatment with Ivermectin,” he said.
“Diseases could easily resurge if we stopped our vigilant use of this drug and research in its use.”
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