Onchocerciasis

The United Nations battle against river blindness has made outstanding progress at best. It is an example of inter-agency partnership and international cooperation against a major health and socio-economic development problem.

On 27 June 1997, the Heads of the Food and Agriculture Organization of the United Nations (FAO), the United Nations Development Programme (UNDP), the World Bank, the World Health Organization (WHO) and other development partners issued a declaration calling for the elimination of river blindness or onchocerciasis throughout Africa by the year 2007. The declaration was signed on the occasion of the unveiling of a statue depicting a blind African man being led by a child (see photo).

Onchocerciasis is a debilitating and often blinding disease endemic to tropical areas of Africa, as well as of Central and South America. Also known as river blindness and "the lions stare", it is caused by a parasitic worm (onchocerca volvulus), which lives and reproduces for up to 14 years in the human body. It is transmitted to infected individuals by the bite of the blackfly which breeds in fast flowing rivers, hence the name river blindness. The adult worm produces millions of infant worms which cause unbearable itching, loss of skin color, rapid aging and unsightly skin disease. Victims are often blind by the time they reach their mid-thirties.

It is the third leading cause of blindness in Africa, where 80 million people are at risk and 18 million actually affected. About 400 thousand have been blinded by the disease. It is most prevalent in the savannahs of West Africa - that area of grasslands, shrubs and trees between where the Sahara stops and the coastal rainforests begin. Here the basin of the Volta River provides the blackfly with ideal places to lay its eggs. Once they hatch, the blackflies can carry the disease flying over distances of up to 400 kilometres.

The endemic health aspects in this Sahel area have lead to adverse social and economic consequences as entire communities often abandon these fertile riverside areas to move to less productive areas away from blackly infestations. In the past, this has lead to severe food shortages, the disintegration of community life and additional burdens on already impoverished populations.

The Onchocerciasis Control Program (OCP)

In 1972, two French scientists working in the area of Bobo Dioulasso in western Burkina Faso (then Upper Volta) decided that a possible solution for the onchocerciasis disease would be to destroy the black fly when it was most vulnerable - at the larvae stage. If the blackfly could be prevented from reproducing for 14 years, the time an adult worm lives in the human body, the parasite reservoir in affected humans would die out. If that were to happen, the blackly could return, bite and cause annoyance, but there would no longer be any disease to pass on.

Furthermore, they reasoned, the breeding sites could be easily found - one only had to look for the fast-flowing and churning water, where the female blackflies look for oxygenization to lay their eggs. The eggs are laid in batches of 200-800 deposited just below the surface of the river. Because they are sticky, they cling to tree branches, plant stems, and rocks. They hatch within two days and the larvae either continues to stick to the surfaces or drift off in the current, so the spraying would have to be done once a week.

After studying this proposal, Robert McNamara, then President of the World Bank, was convinced that the approach was worth trying. He helped to organize an international effort to finance the OCP. The FAO, WHO and UNDP joined the Bank, and the OCP was formally launched in 1974. The OCP initially involved seven countries - Benin, Burkina Faso, Ghana, Cote d'Ivoire, Mali, Niger and Togo. Four other countries - Guinea, Guinea-Bissau, Senegal and Sierra Leone - and 20 donors have since joined the Program.

The objective of the OCP has been to eliminate onchocerciasis both as a major public health problem and as a serious constraint to human settlement and socio-economic development in the participating countries. The primary tool has been vector control to prevent the blackfly from reproducing and hence transmitting the disease. It consists of weekly helicopter spraying of larvacide along 18,000 kilometres of rivers in an area of 1,235,000 square kilometers (more than twice the size of France). The choice of the environmentally-safe insecticides is screened by an independent ecological group. Now, instead of spraying one larvacide, a rotation of different environmentally-friendly insecticides is used. The most prevalent is in fact a biological agent, not a chemical, and has been used in controlling gypsy moths.The OCP control took another turn in the 1980s, when the pharmaceutical giant, Merck & Co., Inc. began testing a new drug called ivermectin - the trade name is Mectizan. After testing, it was found to be effective at paralyzing and expelling the infant worms in the body and, as a result, halting the progression of the disease. One single dose of Mectizan reduces the levels of microscopic worms to near zero with minimal side-effects. However, it does not kill or eliminate the adult worms in the human body, so the drug must be administered every year and is most effective when combined with vector control. It was apparent from the very beginning that the target population would not be able to afford to pay for Mectizan. Therefore, in 1987, Mercke & Co. Inc. pledged to provide Mectizan free of charge for as long as needed to as many who need it to treat fiver blindness. The medicine now reaches 16 million people who live in endemic areas. The cost of protecting each person in the 11-country OCP area is an estimated $0.54 per annum in 1985 constant dollars.

Since it began, the OCP has virtually eliminated river blindness in the original seven target countries. By 1996, more than 34 million people were protected against the disease. About 2 million people who were once seriously infected have fully recovered, and estimates show that 600,000 have been saved from blindness. Twelve million children born since the OCP began face no risk of contracting the disease.

Moreover, approximately 25 million hectares of arable fertile riverine land has been opened for resettlement - enough to feed 17 million additional people each year. There has also been significant additional labour productivity from reduced onchocerciasis-related diseases.

The changes are indeed impressive. If you drive a few kilometers out of Bobo Dioulasso to the Kou Valley, the luxuriant rice fields stretch in all directions neatly divided by drainage canals. This is one of the sites of the FAO's Special Programme for Food Security. The primary purpose of the Special Programme is to help low-income food-deficit countries like Burkina Faso to reduce their food insecurity by accelerating food productivity and production. The Programme focuses on food crops such as rice which have good potential for rapid, substantial, stable and sustainable production increases while at the same time safeguarding natural resources. The rice production in former onchocerciasis-endemic regions of the country would not have been possible without the OCP.

In fact, the OCP has been widely and justifiably recognized as a very successful and effective regional development programme. This was recognized when in 1995 the original four sponsors launched a new programme - the African Program for Onchocerciasis Control (APOC) - to expand the control to 19 African countries which fall outside the scope of the original OCP countries.

The APOC goal is to establish sustainable, community-directed ivermectin delivery systems coveting 50 million people. These systems will be established and are expected to become entirely self-sustaining by 2007. The total cost of APOC over the 12-year period is estimated to be $161 million. The average cost per person treated per annum will be approximately 25 cents.

These two programmes - the OCP and the APOC - exemplify the success attainable when intergovernmental organizations, non-governmental organizations, Governments and the private sector collaborate closely on a well defined target: the elimination of river blindness. More than that, it establishes a precedent for efforts to eventually eliminate other tropical diseases such as schistosomiasis and guinea worm. But it does more than that. By eliminating onchocerciasis in African countries, the OCP and APOC are greatly improving the quality of life of millions of people. If successful, the programme could reach an additional 50 million people within the coming decade.

Meanwhile, massive population movements are occurring in the OCP area, with evidence of degradation of the environment, resource base and agricultural productivity. The challenge now facing the international community appears to

be the provision of follow-up support to ensure sustainable settlement and socio-economic development of the oncho-freed areas.

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