"¡Adiós, Filaria!" Guatemala Eliminates Onchocerciasis
River blindness, also known as onchocerciasis, has endangered Guatemalan’s eyesight since at least 1915. Last month, however, just over a century after the country’s first onchocerciasis diagnosis, the World Health Organization (WHO) declared the disease officially eliminated from the Land of Eternal Spring.
River blindness is an infectious disease caused by Onchocerca volvulus. This parasitic worm is spread by the bite of the black fly, which need human blood in order to develop their eggs. Currently, the best treatment for onchocerciasis is ivermectin, an antifilarial drug. Merck, the producer of ivermectin, has pledged to donate the medicine “for as long as needed.”
Not long ago, widespread elimination seemed out of reach. In the 1990s Guatemala accounted for 41 percent of people at risk in the Americas. But through the work of the Onchocerciasis Elimination Program for the Americas (OPEA), a partnership program involving the Carter Center, the Guatemalan government, the Pan-American Health Organization and Merck, hundreds of thousands of people have received critical treatments. As a result of OPEA’s perseverance, Guatemala has joined a handful of countries that have eliminated river blindness, including Columbia, Ecuador and Mexico.
Despite the progress in Guatemala, river blindness still remains the second leading infectious cause of blindness worldwide. It is estimated that in 2015, 1.1 million disability adjusted life years, or DALYs, were lost to river blindness, and only 60.4 percent of those requiring treatment received the necessary medical care. The minimum therapeutic treatment rate needed to achieve regional elimination is 65 percent, a target many countries are far from reaching.
Increased treatment coverage and innovative drug distribution techniques will likely play a pivotal role in achieving elimination elsewhere around the world. Even at the peak of the onchocerciasis epidemic in South America, the prevalence of river blindness was low, numbering in the hundreds of thousands, compared to the prevalence of the disease in Africa, where over 120 million people are infected.
Novel medicines or vaccines may also be needed. Unfortunately, ivermectin can have contraindications with Loa loa, another parasitic worm that in certain localities is co-endemic with onchocerciasis. A potential solution is an onchocerciasis vaccine. Such a vaccine is currently under development by the Onchocerciasis Vaccine for Africa initiative, in partnership with the Sabin Vaccine Institute.
There is no doubt that challenges remain in the effort to achieving widespread elimination of river blindness, but Guatemala’s success is a milestone worthy of praise and celebration. Fittingly, the Guatemalan city of Patulul arranged a parade to celebrate the country’s triumph and the death of the disease. While the road to overcoming river blindness globally may be long and arduous, there are few things to be celebrated more than a country that has eliminated a disease – closing more than a century of suffering, and preventing a century more.
Photo from the Carter Center.