Commonwealth Health

Tackling river blindness in Africa
Richard Porter

Richard Porter, Executive director, Sight Savers International and Task Force member of Vision 2020 writes about the efforts directed at the prevention and cure of onchocerciasis.

Onchocerciasis is a blinding disease which occurs in some 30 countries in Africa. More than 17 million people are at risk from the disease and as many as one million are already blind or severely visually impaired.

The fly which spreads onchocerciasis breeds in fast flowing rivers, so that the disease mainly affects fishing and farming communities, often those in remote rural areas.
When highly prevalent, onchocerciasis forces communities away from the fertile river valleys as village blindness rates reach devastating proportions. With too few able-bodied people left to tend fields, food shortages and economic collapse force residents to abandon homelands. Moving to hard scrabble highlands offers some respite from further infection, but is not without its own problems, poor soils and little water cripple farming efforts.
Ninety-nine percent of the world's river blindness cases occur in Africa, with the remaining cases located in isolated areas of Yemen and six Latin American countries.

The tackling of onchocerciasis is one of the most successfully co-ordinated programmes between international institutions, national governments, international non-governmental organisations and a pharmaceutical company. Two concerted programmes, the Onchocerciasis Control Programme and the African Programme for Onchocerciasis Control along with the commitment from Merck and Co to supply the drug, Mectizan(r), for as long as necessary, have led to significant progress in tackling onchocerciasis in Africa.

Commonly called river blindness after its geographic locus and most visible symptom, those infected with the Onchocerca vovulus parasite are cursed with interminable itching, thickening and depigmentation of the skin, and in an average 10 per cent of cases, permanent blindness.

Before international action, in some heavily infected villages in West Africa, this figure was several times higher Blindness among adults often ran above 30 per cent. For those infected, the adult worms (macrofilaria), live coiled in the host for 10-14 years, spewing forth millions of tiny worms (microfilaria). These microfilaria move around the body, eventually invading the eye and causing irreversible blindness. The microfilaria can mature to adult worms only after undergoing an intermediate maturation in the blackfly that transmits the disease.

The first concerted effort to tackle the disease was the Onchocerciasis Control Programme (OCP) for West Africa. OCP was founded in 1974 as an unprecedented collaboration between the international donor community and UN agencies, including the World Bank and World Health Organisation. The programme was created with the dual mandate of eliminating the disease and building local capacity for surveillance to ensure that the disease does not return. This strategy opens oncho-freed areas to resettlement and cultivation in the near term and promotes increased, sustainable agricultural production in the long term. Initially operating in seven West African countries, OCP expanded in 1986 and now involves 11 countries.

OCP has virtually stopped transmission of onchocerciasis by spraying environmentally safe insecticides at the breeding sites of the black flies. Since the early 1990s, OCP has also used the drug Mectizan" (ivermectin). These methods have reclaimed 25 million hectares of land which had been abandoned. It is estimated that this area is capable of producing food to feed an additional 17 million people per year, utilising existing local technologies and cultural practices

The remarkable success of OCP and the prevalence of onchocerciasis in the remainder of sub-Saharan Africa led to the development of a second programme, the African Programme for Onchocerciasis Control (APOC), launched in 1996. APOC's objective is to rid the remainder of Africa of onchocerciasis. The programme extends Mectizan(r) coverage to the remaining 19 endemic African countries, using its principal strategy of Community-Directed Treatment (CDTI).

In the 1980s a drug called Mectizan(r) was developed by Merck and Co as a safe and effective treatment for onchocerciasis.
The drug kills the immature, worms in people but because it does not kill the adult worms, the drug must be taken annually. The adult worm usually lives for around 15 years so the drug has to be taken for that period to interrupt transmission. Merck and Co have committed themselves to supplying the drug free for 'as long as needed to as many as need it'. The challenge, therefore, is to deliver Mectizan(r) to everyone who needs it every year over a long period.

The principle of CDTI is to empower the community affected by onchocerciasis to take responsibility for the management of the annual treatment cycle. This has enabled communities to successfully fight river blindness in their own villages, relieving suffering, boosting productivity, and slowing transmission across the entire region-from Western, Central, and Eastern Africa in the North to the Democratic Republic of Congo, Malawi, and Tanzania in the South.

The treatment methodology has to suit their needs and fit in with their seasonal activities, if it is to be sustained over 15 years. Thus communities select their own Community Directed Distributors (CDDs) who are trained in the basic facts of the disease and on how to organise a village treatment programme. The CDDs, register everyone living in each household, arrange to pick up the tablets from the local health centre, and supervise the treatment. They keep the records, retain enough tablets for absentees, and return the unused tablets to the health centre.

After just six years of operations, APOC has established 74 projects, which shortly will treat 40 million people per year living spread over 14 countries. As the program expands over the next few years, 60 million people will be treated annually in 19 countries. These results have been achieved by all of APOC's stakeholders, working in partnership, each focused on its specific strengths. By the end of its operations, this partnership will have achieved significant results, including:
* Preventing approximately 40,000 cases of blindness annually in the 19-country area
* Alleviating unbearable itching and eliminating skin disease
* Protecting the US$556 million investment in the Onchocerciasis Control Programme by eliminating the threat of re-invasion from neighboring countries, notably Nigeria
* Eliminating onchocerciasis as a public health problem throughout the entire continent of Africa, where 99 per cent of the world's cases occur.

Sight Savers International (SSI), the leading development organisation in the UK dealing with the prevention of blindness, has been involved in tackling Onchocerciasis for over 10 years, mainly through supporting the work of distributing the drug Mectizan(r). SSI works closely with national governments to provide training for the community directed distributors and logistical support, such as bicycles which can mean the difference between reaching 2 or 5 villages. SSI is currently supporting the treatment of 7.5 million people in 10 countries in Africa.

There are still a further 30 million people at risk from onchocerciasis in Africa in need of treatment, most of them living in communities in areas of conflict, with little or no access to health services. In order to reach these people, the NGDO Group and its partners need to attract additional funds, and encourage other international and local NGDOs to undertake new projects, especially those with expertise in conflict areas. This is the challenge for the next ten years.

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