How it began
In 1915 the Guatemalan physician Rodolfo Robles Valverde, born in Quetzaltenango and trained in Paris, found the worm Onchocerca volvulus in a nodule on an eight-year-old patient from the coffee-growing zone of Guatemala later called the Central Endemic Zone. From clinical observations among plantation workers he linked the infection, the nodules and eye disease. It was the first description of onchocerciasis in the Western Hemisphere, and the disease there came to be called Robles disease.
Before it existed
Onchocerciasis was known in Africa, where Patrick Manson had first described the adult worms in 1890, but it had not been recognized in the Americas Robles was the first to describe the cause of the disease there, working from what he saw in patients on the coffee plantations, and his work established the relationship between infection, nodule rates and ocular disease.
How it works
Adult worms live in fibrous lumps under the skin, called nodules, where females release microscopic larvae. These spread through the skin and can enter the eyes, causing inflammation, itching, impaired vision and blindness. Black flies of the genus Simulium pick up the larvae when they bite and pass the infection on. Robles extracted a worm from a facial nodule and attributed the eye disease to the parasite.
What changed first
Robles's work pointed to a direct remedy, cutting out the nodules. In the mid-1930s the Guatemalan health ministry set up traveling surgical brigades that removed nodules across the endemic zone, a campaign in which Robles took part. The zone proved to be the largest focus of the disease in the Americas.
What lasted
Mass treatment with the drug ivermectin began in Guatemala in 1988 after Merck's 1987 donation, and twice-yearly rounds reached at least 85 percent of eligible people from 2000 to 2011. After three years of surveillance found no infected flies, Guatemala's health ministry declared transmission eliminated from the Central Endemic Zone in 2015, one hundred years after the discovery.
