Eliminating river blindness in two Nigerian states—a first for this major hotspot—could invigorate decades-long effort to deploy ivermectin to eliminate disease globally
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New data indicate that mass treatment with ivermectin—a drug that was a workhorse of tropical medicine long before it emerged as a controversial COVID-19 treatment—has eliminated river blindness transmission in two states in Nigeria, the first Nigerian states to achieve this distinction in a country that has the world’s highest burden of the disease.
The findings, presented today at the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH) by researchers from The Carter Center and Nigeria’s federal and state ministries of health, represent a major milestone in a decades-long effort to eliminate a leading cause of preventable blindness. River blindness, also known as onchocerciasis, is caused by tiny parasitic worms transmitted by infective bites from blackflies that breed in rapidly flowing rivers. In humans, the worm’s embryonic larvae routinely produce eye lesions that eventually can lead to blindness. River blindness is found widely in Africa, and there are isolated pockets of disease in Brazil, Venezuela and Yemen.
“Nigeria is where the fight to eliminate river blindness will be won or lost, which is why we are excited to have evidence indicating that the Plateau and Nasarawa states, with a combined population of more than five million people, appear to be the first in the country to have stopped disease transmission,” said Dr. Abel Eigege, a Program Director for The Carter Center in Nigeria. “It’s taken 25 years of hard work by community volunteers to distribute the medicine, and particularly strong commitments from Nigeria’s Federal Ministry of Health, Merck’s ongoing donation of ivermectin, and many donors and partners. But we are hoping this success can accelerate elimination efforts elsewhere in Nigeria and throughout Africa.”
In a separate presentation, The Carter Center’s Dr. Emmanuel Emukah reported that there is also evidence that disease transmission has been “interrupted” in Nigeria’s Delta State. Interruption is a critical first step towards achieving elimination since it allows ivermectin treatments to be stopped and post-treatment surveillance to be launched before elimination is declared. He also presented evidence indicating that four other Nigerian states may soon reach the interruption stage.
While the US Food and Drug Administration warns against using ivermectin for treating COVID-19, in 1998 it found that ivermectin was safe and effective in humans for treating river blindness and a human intestinal infection caused by parasitic worms known as strongyloidiasis. River blindness elimination efforts have focused on mass drug administration (MDA) campaigns in which a single dose of ivermectin—and in a form approved for use in humans—is given repeatedly, once or twice a year, to the entire treatment eligible populations of villages in areas where river blindness is transmitted. The global campaign was catalyzed in part by the Mectizan Donation Program that was launched in 1987. Eigege said one reason the campaigns have been embraced by people in local communities is that ivermectin has additional benefits in treating other afflictions they routinely suffer, including intestinal worms, scabies and lice.
Dr. Frank Richards, who spent 22 years leading The Carter Center’s River Blindness Elimination Program and now serves as a senior adviser, said it’s been frustrating during the pandemic to see ivermectin—a drug that has great value for treating neglected tropical diseases—be reframed as a dangerous drug for humans and one that only should be used for treating worms in livestock and pets.
“It is extremely important for the public to recognize that there are formulations of ivermectin approved by the FDA for treating specific conditions—like river blindness—in humans that are incredibly safe when given at recommended doses,” Richards said. “Ivermectin is of enormous proven value for a number of neglected tropical diseases that are a significant burden for millions of people. Before ivermectin arrived, we really had nothing to safely treat river blindness. Look at where we are now! Ivermectin has eliminated river blindness from four countries in the Americas, and, in these ASTMH reports from Nigeria, it is showing that it can do so in Africa as well.”
Richards added that such impact is one of the reasons why the developers of ivermectin won the 2015 Nobel Prize in Medicine.