Where are we in the fight against onchocerciasis or river blindness?

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Tuesday, 20 February 2018

To mark the publication of the one-off supplement of our journal International Health titled “Onchocerciasis: The Beginning of the End”, Dr Adrian Hopkins MBE, an ophthalmologist, NTDs expert and RSTMH Member, gives his view on the progress towards elimination.  

Thirty years, a record-breaking programme donating free medicine, 200 million people a year treated, and the number keeps growing.

What started as a promise from MSD (known as Merck & Co Inc. in USA and Canada) to donate Mectizan® (ivermectin MSD) for river blindness to as many people who needed it for as long as was needed, has led to Mass Drug Administration (MDA) for diseases that affect over a billion of the world’s poorest population.

The programme set its sights on elimination

This donation, which initially was to control the worst cases of river blindness, has developed into a programme that has set its sights on eliminating the disease from most countries in Africa by 2025. We now also have a similar goal for the elimination of lymphatic filariasis in Africa, which combines treatment with albendazole donated by GSK.

30 years ago, I watched as the microfilaria disappeared gradually from the eyes of a patient living close the Tshoppo Falls near Kisangani in what is now the Democratic Republic of Congo.

A child using a stick to lead a woman blinded by onchocerciasis in Nigeria © Mectizan Donation Program
A child using a stick to lead a woman blinded by onchocerciasis in Nigeria © Mectizan Donation Program

This was the first patient I had been able to treat with this “new medicine”. We had already stopped using diethylcarbamazine because of the dangerous inflammatory reaction it caused in the eye. I remember well a patient who came to me having gone blind after taking some and who remained with a serious loss of vision in spite of all the anti-inflammatory treatment we had given him. 

As treatment developed into community-wide interventions, the mapping of the disease improved as did the recognition of the importance of skin disease. And the impact of the programme increased.

In the Americas where foci of infection are small and well separated, the programme went for elimination. In Africa, where there is well over 90% of the disease, foci are large and the blackfly vector can travel far, the objective of the programme was to control disease.

The Onchocerciasis Control Programme in the West added Mectizan® and later the African Programme for Onchocerciasis Control (APOC) working with NGOs adopted MDA, with a particular emphasis on community involvement. This has developed into CDTI or community directed treatment with ivermectin, which empowers communities to organise their own programmes for what is a very long-term intervention requiring annual distribution of the medicine.

Elimination of transmission requires a shift in thinking

In 2009, there was the first consultation in Africa on the possible elimination of transmission of onchocerciasis. This requires a paradigm shift in thinking. Elimination of a disease is a completely different ball game to control of the disease, or “elimination as a public health problem”.

For example, in Africa, treatment had not been given in so-called hypoendemic areas where the infection was at a low enough level that blindness and severe skin disease was not a public health problem.

Eliminating transmission involves reviewing all these foci and deciding on new treatment strategies if transmission is ongoing. New mapping strategies are identified in the special issue of International Health, which focuses on onchocerciasis. More sensitive diagnostics are required to identify these areas, as well as to comply with the latest WHO guidelines for elimination of transmission.

If treatment is needed, what would be the best strategy? Is annual treatment with ivermectin needed, or should new areas start out with treatment twice a year?

With the closure of APOC at the end of 2015, a new programme based at WHO AFRO called ESPEN is being geared up to help with technical advice. However, this is not a major funding organisation like APOC and part of this strategy is to make sure countries take ownership of their national programmes.

Elimination through national committees

National elimination advisory committees are the mechanism for achieving this. Each country can look in detail at each focus of disease and recommend the best strategy to their Ministry of Health, whether this be in the “hypoendemic areas”, or in other areas where progress is not as quick as it should be.

These committees will be sub-groups of the national NTD programmes and will work within the context of these committees as they seek to achieve the SDGs by 2030. These national committees will also have to coordinate well with the lymphatic filariasis elimination programme as MDA with Mectizan® is used for both diseases. 

Of course, challenges remain. One of the most difficult problems over recent years is the problem of coinfection with loiasis and onchocerciasis, which is most common in Cameroon and the two Congos. This has caused major problems for programme expansion. In the last couple of years there has been exciting progress with the development of the Loascope and the Test and Not Treat strategy. This is a problem that can now be solved.

River blindness does not respect national borders

Politics as always can create problems. River blindness does not respect national boundaries, whether in the Amazon forest, on the Venezuela-Brazil border or in Africa. In some areas there is good coordination, but in other areas programmes are vastly different.

Tied to politics is instability. Political instability in South Sudan, DRC and Yemen for example have all created situations where treatment has been delayed. These conflict and post-conflict situations create a formidable barrier to progress and these areas will find it difficult to reach a 2025 target to stop treatment.

Much of the success of the onchocerciasis programme so far has been the development of unique partnerships. This has involved the donation of Mectizan® with all importation costs covered, the national ownership of the endemic countries, NGDOs working closely with governments with financial and technical support, WHO with technical guidelines, and support of the two African Programmes, as well as various academic and research institutions. 

All these have brought us to the point of already eliminating the disease as a public health problem virtually everywhere. The partnership continues. We are at the beginning of the end and the promises of support encourage us to believe we will make it! 

Read the one-off supplement of our journal International Health titled “Onchocerciasis: The Beginning of the End”. The supplement is free to access in its entirety.