Onchocerciasis, also known as “river blindness”, is a parasitic disease caused by the filarial worm Onchocerca volvulus. It is transmitted by repeated bites of infected blackflies (Simulium spp.); which breed in fast-flowing rivers and streams, mostly in remote villages located near fertile land where people rely on agriculture.
In the human body, the adult worms produce embryonic larvae (microfilariae) that migrate to the skin, eyes and other organs. When a female blackfly bites an infected person during a blood meal, it also ingests microfilariae which develop further in the blackfly and are then transmitted to the next human host during subsequent bites.
Onchocerciasis is an eye and skin disease. Symptoms are caused by the microfilariae, which move around the human body in the subcutaneous tissue and induce intense inflammatory responses, especially when they die. Infected people may show symptoms such as severe itching and various skin lesions. In most cases, nodules develop under the skin. Some infected people develop eye lesions which can lead to visual impairment and permanent blindness.
In the late 1980s, an estimated 500,000 people in the Americas were at risk of onchocerciasis in six countries: Brazil, Colombia, Ecuador, Guatemala, Mexico, and Venezuela. The donation of Mectizan (ivermectin) by Merck stimulated new partnerships and opportunities to fight onchocerciasis. After PAHO declared elimination as the goal for the region using a strategy of mass drug administration, a regional partnership, OEPA, was established to focus on reaching that objective. OEPA was launched in 1993 with funding from the former River Blindness Foundation which The Carter Center had absorbed in 1996. Both The Carter Center and PAHO provide the affected national country programs technical assistance; additionally the Center provides complementary financial support.
Today, the population requiring treatment with Mectizan on the continent has fallen by more than 95 percent.
In 2013, Colombia became the first country officially verified by the WHO as free of onchocerciasis. Then, in September 22, Ecuador obtained this verification provided by international organization. The governments of Guatemala and Mexico have both eliminated disease transmission, completed their post-treatment surveillance period, and are getting ready to start the official process to request verification from the WHO.
Transmission only continues in the cross-border region between Venezuela and Brazil, commonly referred to as the Yanomami area. Interrupting onchocerciasis transmission from this final area in the Americas is the biggest challenge to the regional initiative, particularly due to the scattered migratory Yanomami population, who live in the dense, nearly inaccessible terrain of the deep Amazon rainforest. The Ministries of Health in Brazil and Venezuela are working with The Carter Center/OEPA, PAHO, and other partners to meet the goal of eliminating onchocerciasis from the Americas by 2019.
In May 2014 Brazil and Venezuela sign an agreement to accelerate cross-border health interventions and interrupt transmission of onchocerciasis, and in this way complete the program of eliminating onchocerciasis in the Americas. The agreement shows that there is political will in both countries to distribute Mectizan tablets to remote indigenous communities that are settled on their common border.
Carlos Slim Foundation will support the OEPA program to intensify the support to these two South American nations’ initiatives as well as to assist WHO/PAHO in its international verification of the elimination of the disease in the region.
Onchocerciasis in Africa
In Africa there are over 120 million people spread over 31 countries at risk of developing the disease. The progress made in the Americas is a model of hope for the elimination of onchocerciasis initiatives in Africa, where hundreds of thousands have lost their sight because of this disease. On this continent, The Carter Center provides assistance to the Ministries of Health of Uganda, Sudan and Ethiopia and some areas of Nigeria. From August 2014, the organization has assisted in the delivery of nearly 200 million cumulative Mectizan treatments through community channels around the world. The Center hopes to demonstrate practical approaches to eliminate transmission of onchocerciasis in Africa, based on the partnership model implemented in the Americas
Onchocerciasis in Mexico
In Mexico, the disease was first diagnosed in 1923, by Dr. Friedrich Fülleborn. Subsequently, in 1930, a national program that treated the disease through surgery by removing the subcutaneous nodules that form the adult worms. In 1988, a campaign of distribution and use of the oral drug Mectizan began. The medication was considered effective and safe to fight the disease and was part of the Programme for Onchocerciasis Elimination few years later. In 1993, the OEPA joined the fight against onchocerciasis, and by then it had been detected cases in three areas considered foci of transmission in the states of Oaxaca and Chiapas.
By the late 2000s, onchocerciasis was eradicated from foci located north of Chiapas and Oaxaca through implementing a biannual Mectizan distribution and health education. In the southern region of Chiapas, biannual and three times per year drug distribution were implemented to eliminate the disease, which completed its phase post-treatment surveillance during this 2014. With this actions, the country began to file applications for WHO’s formal verification, demonstrating that it is disease free zone. Today, thanks to the leadership showed in this regard and the country’s strong partnerships there are 170,000 people living in the three areas (formerly endemic) of Mexico free of risk of contracting the disease.
The initiative to eliminate onchocerciasis in the Americas, has been forged with the formation of various partnerships, including organizations like the Carlos Slim Foundation, the Bill & Melinda Gates, The Carter Center, US Centers for Disease Control and Prevention Foundation (CDC) the Pan American Health Organization, Merck and the Mectizan Donation Program, the US Agency for International Development (USAID), the Lions Clubs International Foundation and the six countries’ local Lions Clubs, Mr. John Moores and former River Blindness Foundation, the OPEC Fund for International Development, Alwaleed Bin Talal, the Inter-American Development Bank, health ministries of the six endemic countries, several universities in Latin America and the US as well as thousands of community volunteers and many other individual donors.
Through : World Health Organization