Can river blindness enter the elite club of eradicated diseases?

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Dr-MoetiIt has been 44 years since a World Bank president traveled to drought-stricken Upper Volta in West Africa — today called Burkina Faso — and encountered a startling and disturbing scene. Blind people were everywhere, with children often leading adults around.

The cause otheir blindness was a tiny worm, called a “filarial nematode,” transmitted by bites from black flies that swarmed the rivers and streams of Burkina Faso. Strangely, the worms do their damage by dying, which generates toxins that can create lesions on the skin and on the cornea of the eyes.

The buildup of cornea lesions from several years of exposure to the disease causes permanent blindness. That’s why, though technically known as onchocerciasis, it’s more commonly called river blindness.

In the wake of that impressionable 1972 visit, the world mobilized to tackle the problem on a large scale.

Fast-forward to the present, and river blindness is once again bringing disease experts back to Burkina Faso. But they are coming to mark a milestone in the global onchocerciasis control effort.

Disease control has been so successful in Burkina Faso and other affected countries that we’re ready to move beyond merely containing the disease. Elimination of river blindness is the new goal — both from its key strongholds in Africa, where 99% of the disease occurs, and from smaller pockets of infection in Latin America and Yemen.

Completely eliminating onchocerciasis from all areas where it is known to exist would take the world to an extremely rare place: disease eradication.

Disease experts don’t use the term eradication lightly. The club of the eradicated human disease is supremely elite. It has only one member, smallpox. There are other candidates. Polio is perhaps closest to gaining entry into this club. But disease experts and policymakers are now considering how 40 years of work combating onchocerciasis in Africa has made eradication a plausible scenario.

A man impaired by river blindness is featured in this undated photo taken during the World Health Organization's efforts to control the disease in Burkina Faso, (World Health Organization African Region)

Before intensive control efforts were launched in the 1970s, 40 million people were infected with the disease and 160 million were at risk. Now in at least 10 West African countries, it is no longer considered a public health threat. Other areas are not far behind. An analysis published in the Journal of Infectious Diseases of Poverty found that in one large swath of disease hot spots outside West Africa, infections have plummeted to at or near zero.

The battle against river blindness has been waged with two key weapons. Insect control is one factor, but the most decisive intervention involves treating entire communities repeatedly with the anti-parasite medication ivermectin. Merck, the drug’s key manufacturer, has been donating the medication to the World Health Organization, allowing it to be deployed forcefully against river blindness in mass treatment campaigns in which everyone in an area at risk is treated regardless of symptoms.

Repeating mass treatment over several years can eventually eliminate the disease from an endemic region. It does this by breaking the cycle of infection, the passage of onchocerciasis larvae from flies to humans and from humans back to flies. Mass treatment campaigns have reached well over 100 million people. Several weeks ago, in Ouagadougou, Burkino Faso’s capital, I witnessed the administration of the 1-billionth tablet of ivermectin in the fight against river blindness.

The success against onchocerciasis is having a profound influence on the broader effort to fight other “neglected tropical diseases.” It has prompted WHO to launch the new Expanded Special Project for Elimination of Neglected Tropical Diseases. This initiative will continue the fight against river blindness while targeting several other diseases for elimination, including lymphatic filariasis (also known as elephantiasis) and debilitating helminth infections, which are transmitted through soil carried by parasitic worms.

Also, these campaigns involve a significant effort to mobilize resources that empower local communities to strengthen their primary healthcare capabilities. The focus on developing integrated health programs at the local level is precisely one of the approaches that is needed as countries strive to attain universal health coverage.

But fighting infectious diseases is like riding a bicycle. To move forward, you have to keep pedaling. It is extremely important that we keep pedaling against river blindness, all the more vigorously because we are entering what may be the crucial last mile that leads to eradication.

By maintaining support for the battle against river blindness, we will continue to blaze a trail toward elimination for other neglected diseases to follow — to a point in the not too distant future when the club of the eradicated disease may have several new members.

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Written by Dr Matshidiso Rebecca Moeti, WHO Regional Director for Africa.

Published in the Los Angeles Times