How Nigerian states are tearing down silos to eliminate transmission of river blindness and elephantiasis

In many parts of Nigeria, onchocerciasis, also known as river blindness, has been as common as it has been devastating – having stolen the eyesight of an estimated 120,000 Nigerians and causing debilitating complications in many others. The disease has been so common, that researchers interviewing rural Nigerians in 1991 reported its symptoms, including the impairment of vision, are "believed by Nigerian rural dwellers to be part of the natural vicissitudes of aging.” No other country, in fact, has had more people infected or people at risk of contracting the neglected tropical disease (NTD).

One of the leading infectious causes of blindness in the world, onchocerciasis is caused by a worm transmitted by repeated bites of infected female blackflies. It is notoriously difficult to cure – treatment requires reaching affected communities, often in remote locations, with annual or biannual doses of an anti-parasitical medicine for periods spanning a decade.

It has been such a stubborn scourge that when Nigerian health leaders launched their most recent anti-river blindness effort in 1991, their goal was not elimination – instead their goal was simply to reduce the number of people falling ill. “We thought we would be treating onchocerciasis indefinitely,” said Dr. Abel Eigege, the program director for The Carter Center in Nigeria for the past 25 years. “It was a daunting challenge that had plagued our forefathers for generations.”

But 30 years later, health leaders in Nigeria's Plateau (population 3 million) and Nasarawa states (population 2.5 million) have achieved what few initially thought possible – they have delivered 27 million doses of medication over more than 20 years, to eliminate transmission of river blindness.

Another four Nigerian states: Abia (population 4.2 million), Anambra (population 6.2 million), Enugu (population 4.8 million), Imo (population 5.8 million) appear close to the same historic milestone. After molecular testing of more than 52,000 black flies and blood samples from more than 12,000 people, the Ministry of Health has just announced that it will no longer be distributing drugs to stop transmission in those four states and instead will monitor to confirm elimination of transmission.

And another three states, Sokoto (population 6.3 million), Yobe (population 3.6 million), and Gombe (population 4 million), are also suspected of having stopped transmission and are launching the widespread surveying and testing of flies and humans necessary to determine if they can confidently stop distribution of anti-parasitic medicine. Efforts to control the disease continue across more than 20 other Nigerian states. These efforts are led by health officials like Jacob Danboyi, whose own father lost his vision because of river blindness. Danboyi went on to serve as coordinator of Nasarawa state's neglected tropical disease elimination program.

“I cannot express how gratifying it is to see millions of Nigerians free from the threat of river blindness,” Professor B.E.B. Nwoke, chair of Nigeria’s Onchocerciasis Elimination Committee said in a statement. “When we started, many questioned our ambition. Today, I’m proud that Nigeria, once again, serves as a beacon of inspiration.”

What’s more, river blindness efforts served as the backbone for historic progress against other NTDs. The same 17,102 community volunteers across the Plateau and Nasarawa states who educated their neighbors about river blindness and delivered the 27 million doses of ivermectin, also educated their neighbors about lymphatic filariasis (also known as elephantiasis) and delivered 36 million ivermectin-albendazole treatments for the disease – eliminating it from Plateau and Nasarawa states in 2012. This same network of community volunteers also reduced schistosomiasis, commonly known as snail fever, by 62 percent in the two states, and delivered hundreds of thousands of insecticide-treated bed nets to help eliminate lymphatic filariasis and reduce malaria.

This remarkable success demonstrates the potential power of community-based interventions, the benefits that may accrue by breaking down silos in vertical health initiatives, and how leveraging existing health structures can help accelerate progress.

“This success confirms that health interventions that logically fit together should go together,” said Dr. Frank Richards, who served as director of the Carter Center's River Blindness Elimination Program, Lymphatic Filariasis Elimination Program, and Schistosomiasis Control Program from 2005-2020. “It shows the benefits of moving away from silos. We can’t have a different vertical team delivering each medicine. There are a lot of logistical, economical, and epidemiological reasons for an integrated approach.”

The effort against river blindness in Plateau and Nasarawa states began in 1987 with a historic announcement: the pharmaceutical company Merck had agreed to donate ivermectin – “as much as needed, for as long as needed” – to help eliminate river blindness.

Nigerian health authorities soon launched a vertical initiative, sending out health workers by foot, in four-wheel drive vehicles, or on motorcycles to deliver the medication to far-flung villages once a year. By the mid-1990s, authorities realized that this approach wasn’t regularly reaching the most remote villages, which often had the highest rates of the disease. They shifted their approach and, with the support of the Carter Center, established a community-based distribution network.

Thousands of community volunteers across both states quickly began conducting annual censuses to determine how many doses of medicine each village would require and followed up by delivering ivermectin to every single household. Many of these communities had never before been reached by the national health system.

Soon, community volunteers across the two states were delivering 2.2 million annual doses to their neighbors. As people’s health improved, communities rallied around the program.

In 2000, efforts to stop the transmission of river blindness were presented with a new opportunity and challenge, when another pharmaceutical company, GSK, formerly known as GlaxoSmithKline, stepped forward with its own historic announcement: it would donate albendazole to be used to treat another neglected tropical disease: elephantiasis. The disease is spread by infected female mosquitos and is often found in many of the same areas where river blindness is endemic.

A single annual dose of albendazole, when used in combination with ivermectin (that was already being delivered to prevent river blindness), can wipe out the parasite that causes elephantiasis.

Rural Nigerians were eager for a treatment for elephantiasis, which often causes heavily swollen legs, disfigurement, and disability. In communities afflicted by this disease in Plateau and Nasarawa states, as many as 10% of residents were affected with heavily swollen limbs and as many as half of men suffered from swollen genitals (hydrocele) from the infection. Authorities estimated that in these two states alone, nearly four million Nigerians would need to be treated for at least 5-6 years to eliminate transmission of the disease.

But there was a serious concern: might integrating the medicines for elephantiasis overburden and derail the successful river blindness program?

Authorities cautiously moved forward with the expansion, increasing the footprint of the program in the two states to serve five to six times as many communities. Program logistics were complicated by the expansion – some communities needed the treatment only for elephantiasis, some only needed the treatment for river blindness, and some needed the medication for both elephantiasis and river blindness.

Dr. Eigege and Dr. Richards, together with their colleagues, noted in follow-up research that rather than dilute the impact of the program, an integrated approach accelerated progress. He and his colleagues wrote in The American Journal of Tropical Medicine and Hygiene that "the integrated concept demonstrated here represented an important opportunity that should be seized by governments and donors alike, as it may ultimately be as important to the public health of Africa as childhood immunization.”

Dr. Eigege explained that “integration is better for the patient, better for the community, and reduces costs by about 41%. When you think about sustainability and impact – integration is key.”

Buoyed by successful integration, authorities incorporated the distribution of insecticide-treated bed nets into their program in 2004. The bed nets not only helped prevent the spread of lymphatic filariasis, but also helped prevent malaria.

The Nigeria Federal Ministry of Health and its partners developed co-implementation guidelines for a coordinated effort to eliminate both malaria and lymphatic filariasis. The guidelines strategically map out shared interventions to maximize impact and reduce redundancies, aligning activities including health education, community-based action, distribution of long-lasting insecticidal bed nets, and mass drug administration. These guidelines are the first of their kind in Africa.

In 2006, authorities further expanded efforts, training the same community volunteers addressing river blindness and elephantiasis to also deliver treatment for schistosomiasis, another common neglected tropical disease caused by a worm that can cause malnutrition, anemia, and organ damage. Community volunteers provided a single dose of praziquantel to all school-aged children and eligible adults. By delivering the medication outside of schools, community volunteers were able to reach even the poorest families, whose children sometimes never enroll, have poor attendance, or leave school early.

Again, Dr. Eigege, Dr. Richards, and their research colleagues found that integrating schistosomiasis and elephantiasis into the river blindness program improved “the latter’s sustainability, by capitalizing on cost savings and broadening the programs' benefits and popularity. In fact, the enthusiasm expressed for the expansion of the popular Plateau/Nasarawa state programs during surveys suggests that integration with LF and SH could increase [ivermectin] consumption for [onchocerciasis] rather than decrease it.”

Explained Dr. Richards, “All of this worked because it was community based. You couldn’t achieve this by getting mobile teams into a land cruiser and distributing medicines to thousands of communities.”