The World Health Organization announced at a meeting in Bogotá on July 29 that, after applying during 12 years (1996-2007) an anti-parasitic treatment to the residents of the community of Naicioná, Colombia has managed to completely eliminate
the tropical disease caused by the bacterium carried by a parasite and transmitted by the bite of a black fly that abounds in tropical rivers.
Naicioná is a small village of 1,400 inhabitants in southwestern Colombia. This was the location of the last outbreak in the country of Onchocerciasis, a disease prevalent in sub-Saharan Africa
, but also common in Brazil, Ecuador, Guatemala, Mexico and Venezuela.
Onchocerciasis, also known as "river blindness", is a disease caused by the infection of Onchocerca volvulus
, a parasitic nematode (a roundworm) (1, see below). The parasite is transmitted to humans through the bite of a black fly of the genus Simulium
. The nematode carries an endosymbiont bacterium (2) known as Wolbachia pipientis
. The larva of the nematode spreads within the body of the host, and when the worm dies, the bacteria are released, triggering an immune response causing skin irritation, and can trigger a severe inflammatory response in eye tissues causing blindness.
Onchocerciasis is second only to trachoma (3) as an infectious cause of blindness in the world. Currently, more than 500,000 people are visually impaired and 270,000 people are blind as a result of onchocerciasis infections.
The first time the disease was detected in Colombia
was in 1965 when a 39-year-old man was slowly losing his vision. Since then, people engaged in gold mining in the Chuare River region, where the Naicioná community is located, were affected with the same problem.
In 1996, a campaign started in Naicioná, which was identified as the focus of the disease, led by Colombia’s National Institute of Health with the collaboration of international researchers of the Carter Center
that coordinates the Programme for Onchocerciasis Elimination in the Americas (OEPA
The researchers visited the sick twice a year to supply an anti-parasitic drug (“Ivermectin
”) donated by Merck. The campaign ended in 2006 when it was shown that the transmission of the parasite had stopped and the small population of Naicioná went into a phase of epidemiological surveillance.
Former US President Jimmy Carter was the guest of honor at the ceremony in which WHO and the Pan American Health Organization (PAHO) presented to President Juan Manuel Santos of Colombia, the document certifying the eradication of "river blindness".
Ecuador is expected to become the second country in the world to eradicate river blindness. No new cases have been reported in this country since 2009. Mexico and Guatemala have more recently halted the cycle of river blindness transmission. The program is focusing now on the remaining endemic areas of Brazil and Venezuela.
(1) Nematodes are roundworms living in various environments including soil, water or inside other organisms. About 28,000 species have been described of which about 16,000 are parasitic.
(2) An endosymbiont is any organism that lives within the body or cells of another organism without affecting its survival.
(3) An infectious disease caused by the bacterium Chlamydia trachomatis