Onchocerciasis, also known as River Blindness, is a neglected tropical disease that causes tremendous disability and suffering for individuals in some of the poorest communities on the planet. It is caused by the tiny parasitic worm Onchocerca volvulus, which is transmitted by the Simulium blackfly. The name River Blindness is derived from the fact that the illness is most intensely transmitted to persons along rivers near fast moving water and the parasitic worm it transmits can cause blindness. In addition to causing blindness by invading the eye, the worm can cause debilitating skin disease—called troublesome itch— that can keep people awake at night, result in skin infections, and reduce the ability to support oneself. More than 100 million people are at risk for River Blindness and more than 30 million are infected with the parasite. Working as a medical epidemiologist at CDC, I am privileged to be among the many global health partners who are striving to eliminate onchocerciasis and the pain and suffering it causes for good.
Fortunately, the devastating effects of the disease can be prevented, sometimes even reversing some forms of early eye disease and improving skin symptoms, by treatment once a year with a pill containing a medication called ivermectin (trade name Mectizan®). In 1987 Merck & Co., the company that developed ivermectin, created the Mectizan® Donation Program for use in mass drug administration programs that treat entire communities. This strategy of treating entire communities is used for control of several types of neglected tropical diseases and is one of the best buys in public health. Since 1987 more than 1.5 billion ivermectin treatments have been given to persons at risk. Because the medication is donated, the cost to distribute it is only about 58 cents per person treated. As of 2010 about 6 million people still suffered from skin disease, 800,000 suffered from visual impairment, and 300,000 suffered from blindness, reflecting around a 60%, 30% and 50% decrease respectively of people debilitated by onchocerciasis since the start of the African Programme for Onchocerciasis Control (APOC) in 1995.
The Onchocerciasis Elimination Program for the Americas (OEPA) also seized the opportunity to put this generous donation program to use and adopt an aggressive response to the disease that has nearly eliminated the parasitic worm from the region. OEPA began in 1993 with once-a-year mass drug administration programs to treat entire communities at risk. As the beneficial impact of treatment became apparent, OEPA soon started treating some communities two or more times a year to accelerate progress. As a result of these intensive efforts, they are on the verge of eliminating onchocerciasis in the Americas. Of the more than 500,000 people who were at risk when the program started, fewer than 25,000 will require treatment in 2013 as a result of the gains made through OEPA. Quite an accomplishment! You can read more about this impressive success story in this week’s CDC Morbidity and Mortality Weekly Report.
In Africa, where 99% of people at risk for River Blindness live, there is now hope that the disease can be eliminated. Country-led programs, with programmatic support and technical assistance from the Carter Center and APOC, have developed a network of community health workers who help distribute the donated medication to those who need it. Along with lessons learned by OEPA, studies conducted in Africa have demonstrated that it is possible to eliminate parasite with ivermectin treatment as a primary intervention in this region as well. Countries and their global health partners, including CDC, are increasingly excited that such a feat may well be within our grasp.
CDC is working diligently to expand the reach of programs that directly administer treatment and prevention programs for River Blindness. Building on scientific work performed in the Americas, with the generous support of the Bill and Melinda Gates Foundation, CDC scientists are working to improve our ability to check the progress of programs in Africa. We have been working to improve diagnostic testing in Uganda and Ethiopia in collaboration with the African Field Epidemiology Network (AFENET) and ministries of health, and we are planning similar work in the Democratic Republic of Congo and other countries. These tests will assist programs in measuring the impact of ivermectin treatment on the disease in communities and help determine when the parasite has been eliminated. If the parasitic worm is eliminated, communities will be able to stop preventative treatment for good. But stopping treatment too soon could allow these parasitic worms to regain a foothold in the communities, so we must be sure that we get it right.
I am privileged to be one of a small team at CDC striving to eliminate onchocerciasis for good. Although the fight will continue for some time, this is one battle that we can win. Doing so will be an effort that will require the combined efforts of scientists, public health officials, non-governmental organizations, and most importantly communities in the Americas, Africa, and the Middle East.