Onchocerciasis

A public health problem nearing a solution

Definition

A child guides their blind parent / Credit : Sightsavers

In many regions of tropical Africa, it is children who have to guide the steps of the blind.
Some years ago, people used to find "cursed villages" near rivers where almost all adults had become blind. Children were forced to leave school, if schools even existed at all, to take care of their parents... while they wiated to become blind themselves. There was no curse on any of these villages. They were simply situated near running water that the villagers used to drink and irrigate their fields... but also allowed small black flies, known as simulium flies, to develop. These flies are the carriers of the parasite that causes onchocerciasis, also known as "River Blindness". _

Black fly breeding site (WHO photo)

Causes

When a black simulium fly bites a human, the worm larvae are transmitted under the skin of the host where they develop into adults and form nodules under the skin. When they breed, millions of larvae are produced which spread throughout the body for 12-15 years.

The accumulation of dead microfilaria around the eye leads to severe ocular lesions (cornea, retina, optic nerve) which can result in irreversible blindness after years of exposure. Elsewhere, the disease can cause skin lesions to appear (dark pigmented spots) sometimes known as ‘leopard skin’ or ‘lizard skin’.

A blind man

History

By its close in 2002, the OCP (Onchocerciasis Control Programme) protected 40 million people against the disease, preventing 600,000 cases of blindness and making 25 million hectares of fertile soil habitable again after previously being deserted. The economic productivity of this programme is about 20% which (according to an evaluation by the World Bank) makes it one of the best performing public health programmes.

The APOC programme (African Programme for Onchocerciasis control) aims to save the sight of some 125 million people exposed to the disease. Amongst them, 18 million people are already infected by the parasite, one million have irreversible ocular lesions and 300,000 are blind.

According to the results of analyses carried out by the Erasmus University of Rotterdam, it is believed that each year APOC prevents 40,000 cases of blindness and saves the equivalent of one million years of economic activity. The strategy implemented by TIDC (Traitment par l’Ivermectine sous directive communautaire) is highly regarded, and considered as a benchmark in health economics. It contributes to the strengthening of the national health system by simultaneously supporting other neglected tropical diseases, other eye diseases, lymphatic filariasis, malaria, geo-helminths…. The OPC (which has been combatting onchocerciasis since 1992) has also put these strategies into practice.

Solidarity at all levels

Ivermectin will allow us to eradicate "river blindness" … As long as anyone threatened by onchocerciasis is treated each year for at least 15 years.

This is the challenge in which the OPC has fought. The Organisation for the Prevention of Blindness is the only French-speaking organisation involved in the WHO (World Health Organisation) African Programme for Onchocerciasis Control qui rassemble 30 African countries whose ultimate objective is aiming to treat 90 millions people.

In order to act effectively, including in the most remote areas, we have developed an immense chain of solidarity, composed of 13,800 volunteer villagers and around 500 health workers at all levels (from doctors to assistants) who have all been trained by the OPC. Some of them also contribute to early screening of sight problems in their villages (primary eye care). Preparing to distribute Ivermectin

Thanks to this fantastic human chain, the OPC covers, for an extremely low cost of just 18 cents of a euro per beneficiary, all those affected by the disease.

Taking Ivermectin tablets

The objective of treating as many people exposed to the disease as possible, including the most remote areas has almost been achieved after 30 years of combatting the disease : the elimination of onchocerciasis is in sight ! In areas looked after by the OPC, more than 3.8 million individuals are regularly protected and are no longer exposed to the risk of onchocerciasis. People have left the most fertile areas because of onchocerciasis.

OPC Results in 2012 : elimination is in sight after 30 years of combatting the disease. More than 3.8 million people have been protected in 7,582 villages in 4 African countries, Congo, Mali Guinée, Sénégal, and they will not become blind. People are returning to the more rich and fertile areas.

Life returns to normal thanks to the program for onchocerciasis control / Credits : extract from "Mara, le regard du lion" film directed by Bernard Surugue (c) Orstom/ird-OMS