Bruce Benton, Manager of the World Bank Riverblindness programmes, on how their success can impact Covid rollout in Africa
With the emergence of Covid-19 there is more awareness of how not just novel but also neglected diseases can affect a global population. With questions around how Africa will deal with the current pandemic and manage the vaccine rollout, the success of the river blindness programmes in West Africa is a salutary example of cooperation and dedication to controlling and eventually eliminating a devastating, widespread infectious disease .
The OCP (Onchocerciasis Control Programme) in West Africa and the follow-on APOC (African Programme for Onchocerciasis Control) covering the rest of the continent were partnerships co–sponsored by the World Health Organization, the World Bank, the United Nations Development Programme and the UN Food and Agriculture Organization. These control efforts were led by World Bank official Bruce Benton, an economist with an interest in public health who had been shocked by the widespread devastation of local communities and personal suffering wreaked by the disease.
Onchocerciasis is caused by a parasite (Onchocerca volvulus) transmitted by a blackfly (Simulium damnosum) that lays eggs in and around rapidly flowing rivers and streams throughout sub-Saharan Africa, six countries in Central and South America, and Yemen. Once reaching adulthood in the body, the 2 ½ foot long parasite spawns millions of microscopic parasitic worms that cause unbearable itching, skin disfigurement and eventually irreversible blindness. On average, victims of the disease become blind at 30 years of age. Onchocerciasis is known locally as the Lion’s Stare, due to the fixed, lifeless gaze of those blinded by the disease. It affects huge swathes of rural populations numbering more than 10m across the African continent that are often unable to work due to disability and are trapped in absolute poverty.
Running from 1974 to 2015, OCP and APOC pulled together 27 donors, dozens of NGOs, 31 African governments and more than 100,000 local communities into a diverse partnership that led the control effort. The success of the West African programme has enabled populations to resettle and cultivate some of the best land near rivers that had previously been abandoned due to the severity of the disease.
Ambitious beginnings
Covering 35m people in 11 countries, the OCP relied principally on vector control, i.e. aerial spraying with insecticides, to prevent the blackfly from reproducing and transmitting the parasite. “It was a very successful control strategy that effectively halted transmission of the disease throughout the West African region,” says Bruce, whose book Riverblindness in Africa, Taming the Lion’s Stare is now published by Johns Hopkins University Press.
“There was no drug at the time. So the only way we could control the disease was to prevent the fly from transmitting it. Vector control worked effectively for more than 25 years and largely eliminated onchocerciasis throughout most of West Africa.”
During the 1980s the wonder drug, ivermectin, was found to be effective against onchocerciasis by scientists at the American pharmaceutical giant, Merck. In collaboration with the Kitasato Institute in Japan, ivermectin was discovered from a compound found in a soil sample on a golf course in Kito, Japan. Through clinical trials it was learned that ivermectin, given once per year, killed off 95 per cent of the microscopic worms (microfilariae) in the human body with virtually no side effects. However, it did not kill the adult worm, which continued to live in the body for up to 15 years. Hence, ivermectin needed to be given at least once a year for the 15–year lifespan of the adult worm. By killing the microfilariae, ivermectin stops the itching, prevents blindness and halts transmission over time. Because onchocerciasis is concentrated in the poorest populations in remote rural areas in some of the poorest countries in the world, Merck decided in 1987 to donate ivermectin, under the brand name Mectizan, for “as long as needed to as many who need it.” It was the first major drug donation for a disease in the developing world and set a precedent that has since led to follow-on drug donations from other pharmaceutical companies for all of the major neglected tropical diseases.
“Mectizan became available through Merck’s donation program in the early 1990s. Under OCP, it was used as a supplement to vector control and enabled that West African programme to be brought to a successful conclusion in 2002,” says Bruce. “However, the drug became central to the control strategy for the follow-on programme, APOC, covering the rest of Africa. Many of the countries covered by APOC were heavily forested which prevented insecticide spraying via helicopters. The availability of Mectizan permitted oncho control to be widened to cover 20 additional countries in East, Central, and Southern Africa. And, in 2009 it was discovered under APOC that where the drug had been used for 15-17 years, the disease had completely disappeared. Consequently, the objective under APOC shifted from control to elimination of the disease throughout Africa via sustained Mectizan treatment.”
Learning the lessons
Under the OCP there were more than 1000 people working on the programme, many working as flycatchers on river banks to catch and dissect flies to determine whether they were infective with the parasite. “OCP was high tech and expensive because we used a fleet of helicopters to spray up to 50,000 km of rivers a week, more than twice the lengths of the Mississippi, the Missouri, the Ohio, and the Columbia Rivers combined. Although the overall cost was high, it averaged out to less than $1 per person protected per year,” Bruce says.
“Vector control under OCP worked well, although the fly eventually became resistant to temephos, the cheapest and most benign insecticide available at the time, causing a crisis which nearly doomed the effort. But eventually we overcame resistance, for the first time ever, by using operational research to discover backup insecticides that were environmentally safe and used them in rotation to defeat resistance – a huge achievement, really.”
Under the second programme, APOC – which was launched at World Bank headquarters in 1995 – the control strategy was based solely on drug distribution through local communities. Once it was determined that Mectizan treatment could stop transmission, the objective shifted from eliminating the disease as a public health problem to eliminating the disease entirely. APOC ended in 2015, but elimination of the disease remains the objective under a third programme, ESPEN (Expanded Special Programme for the Elimination of Neglected Tropical Diseases).
Through operational research under APOC, a method was found to reach a high percentage of the infected population in remote areas by delivering Mectizan through local communities. The method became known as Community–Directed Treatment, or ComDT. “Under ComDT, the communities selected volunteer community distributors who took responsibility for ensuring that all those at-risk in the community would receive a dose of Mectizan at least once a year. That proved to be extremely effective in ensuring that a high enough percentage of the at-risk population received the drug to stop transmission over time and eventually eliminate the disease,” says Bruce.
“Up to 35 NGOs worked to help train the community–directed distributors on how to deliver the drug, recognise potential side effects, and keep records to ensure that the drug was safeguarded and readily available when needed.”
“What was so amazing about OCP and APOC was that they were led by a wide-ranging partnership comprised of more than 100 diverse partners who all pulled in the same direction. This was possible because the programme objective and the strategy to achieve that objective were kept simple and consistent over time. Hence, all the partners had the same understanding of the end goal and what was needed to get there. Also, the various partner groups – donors, African governments, sponsoring agencies, NGOs, and research entities – had different, but complementary skill sets, which led to synergistic results through a division of labour.
“In managing the partnership, we went out of our way to recognise each partner as responsible for the success of the effort. Spreading credit around liberally was important in ensuring that each partner would stick with the programme over the long haul. It also helped the partners – be they governments, foundations, or NGOs – retain support domestically as the word got out that they were responsible for the success. And the continuation of support was remarkable. The original nine donors that launched OCP in from 1974 were still supporting the effort 35 years later.
“There are a lot of lessons to be learnt from how the partnership was put together, held together, and sustained over decades. It was particularly strong on cooperation, operational research, and fund mobilisation over many years, which enabled the programmes to weather crises and take advantage of new technologies and other new opportunities. We learned it had to be a regional approach, rather than country–by–country effort due in part to the up to 500 km flight range of the blackfly. If the disease was eliminated in one country it would return quickly via re-invading infective blackflies from a neighbouring country. The regional nature of the programmes also had the advantage of producing high-value regional public goods benefiting all participating countries, such as Africa-wide operational research, the application of new technologies, and the development of common concepts and methodologies.”
Currently, according to the WHO, 205m people are at risk of contracting onchocerciasis, with 20.9m infected – 99 per cent of whom are in sub-Saharan Africa. To date 1.1m people suffer from blindness due to onchocerciasis. And NGOs such as Sightsavers International undertake important work in helping to train community distributors to distribute Mectizan, providing more than 513m treatments to alleviate suffering and prevent blindness.
“The success of the OCP and APOC programmes along with the continuing efforts of NGOs to combat onchocerciasis have alleviated tremendous suffering over the past 40+ years and have promoted economic development in sub-Saharan Africa by increasing human productivity and opening up arable land to resettlement and cultivation,” says Bruce. “I am extremely proud of the results we achieved to create a situation where many of the poorest of the poor are now free of suffering and have regained the ability to lead productive lives.”
Riverblindness in Africa, Taming the Lion’s Stare is now published by Johns Hopkins University Press.