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By Joseph Ndung’u
This spring, three African countries recognized a major milestone: Benin, Rwanda, and Uganda have each been validated by the World Health Organization (WHO) for eliminating at least one form of sleeping sickness as a public health problem. This brings the world a significant step closer to meeting the WHO target of global elimination of this disease by 2030.
These extraordinary accomplishments have been years in the making, reflecting decades of national and international collaborative effort and planning. At the heart of this success story is diagnostic testing, without which disease elimination and surveillance would be impossible.
Sleeping sickness—also known as human African trypanosomiasis (HAT)—has been a scourge of sub-Saharan Africa for thousands of years. Caused by a parasite transmitted by the tsetse fly, no symptoms are apparent at first. Yet following infection, the parasite gradually burrows deep into all the body organs, and eventually the central nervous system, causing poor coordination, confusion, and loss of sleep. HAT is almost always fatal without treatment. Even with a life-saving intervention, debilitating injuries may endure.
Given the progression of the disease, early detection and initiation of treatment is essential to save lives and prevent transmission. But it’s easy to miss HAT in its early stages. The gambiense form of the disease is initially asymptomatic, while the rhodesiense form present signs that are easily mistaken for malaria. Tracking new cases at the population level is also arduous. Many of the communities most vulnerable to this parasite live in rural, remote regions. These hard-to-reach locations often lack resources, infrastructure, and trained laboratory technicians, making it difficult for people to access a reliable diagnosis.
In addition, the gradual elimination of HAT has made monitoring this disease even more difficult. As confirmed cases decrease, knowing where to spot the newest infections becomes increasingly challenging. Yet only through rigorous testing and disease surveillance can we control outbreaks and sustain elimination.
In collaboration with the global health community, Benin, Rwanda, and Uganda have risen to meet the challenge. Adapted, innovative diagnostic tools and strategies, supplemented with efforts to reduce the tsetse fly population, have been central in driving effective interventions.
HAT diagnosis is a challenging, multi-step process. Individuals suspected of being infected first require a blood test to detect antibodies against the parasite. Then, microscopy confirms infection by demonstrating the presence of the parasite in body fluids. In some cases, a cerebrospinal fluid test is also required to determine whether the parasite has advanced into the central nervous system. Only after these assessments to confirm diagnosis can treatment begin.
New tools—particularly the development of rapid diagnostic tests (RDTs) for the gambiense form of the disease—have radically simplified the first stage of diagnosis and made it more accessible to communities living in the most remote places. For example, joint development efforts by FIND, the global alliance for diagnostics, the Institute of Tropical Medicine, Antwerp, and international partners saw two blood tests launched in 2012 and 2013. These rapid tests—one manufactured by Standard Diagnostics and the other by Coris BioConcept—were the first new screening tests developed in decades (and have since been optimized further).
Both tests can now detect telltale disease antibodies in just 15 minutes without requiring special laboratory equipment, training, or a power source. Their portability and ease of use helps decentralize the diagnostic process. As a result, primary healthcare workers in remote regions are empowered to rapidly identify suspected cases and refer them for confirmatory testing, so that people can receive life-saving treatment.
Countries can leverage these new tools to better monitor and track this disease, mapping cases as they emerge. Such efforts enable national control programmes to then take swift and targeted public health measures, such as deciding where to send treatment and supplies and when to take measures to control tsetse fly populations.
Being able to tailor a nation’s testing strategy is imperative to ensure an appropriate public health response. For example, in Uganda, confirmed cases of the gambiense form of HAT have fallen precipitously in the past two decades, from 311 reported cases in 2005 to just 2 in 2017, and no case has been reported since June 2020. As disease prevalence decreases, the strategy must shift from mainly conducting what are called “active screening” to expanding “passive screening”. Whereas active screening requires mobile teams of health workers to go into communities and test anyone at risk, passive screening involves testing potentially infected individuals when they come to primary care facilities. This integrated method of screening is more cost effective than the active approach and it ensures sustainable surveillance for HAT well into the future. Even after elimination, vigilance through passive screening is essential to prevent disease resurgence. In Uganda, FIND has helped expand passive screening by introducing HAT RDTs in 51 strategically located health facilities in the country, and upgrading a dozen of them to confirm disease by microscopy. This effort has helped more Ugandans receive screening and diagnosis close to their homes and it has helped ensure that fewer cases go undetected and untreated to finally reach elimination.
The success of these efforts is also a testament to local, regional, and international collaboration. In 2012, more than 7,000 new cases of HAT were identified worldwide. That figure fell to fewer than 800 in 2019 and continues to decline. Progress has been possible because of the cooperation between international agencies, donors, NGOs, research institutions, industry, and—crucially—national and community-led efforts within these countries. The global health community can hope that soon, other countries will follow the lead of the nations that have eliminated at least one form of HAT. Congratulations to Benin, Rwanda, and Uganda on this historic public health victory.
Professor Joseph Ndung’u is Executive Director of Foundation for Innovative New Diagnostics (FIND) in Kenya