Human African trypanosomiasis (HAT), also known as sleeping sickness, is a parasitic disease caused by protozoan parasites of the Genus Trypanosoma. The disease is transmitted by tsetse flies, and is found in low-income, rural regions in sub-Saharan Africa.
The disease presents in two forms depending on the sub-species of the infecting parasite:
- Chronic infection, which accounts for 98% of reported cases and has a long latency period—people can be infected for years without becoming symptomatic.
- Acute infection, which is more virulent than the chronic form and manifests within weeks or months of infection.
In the early or first stage of illness, the disease causes non-specific symptoms and generally goes undiagnosed. The late stage is associated with invasion of the brain by parasites, which ultimately causes death if left untreated. Early diagnosis is critical: after the disease has advanced to the second stage, treatment procedures are complicated and risky.
In recent years, concerted efforts in surveillance and control of HAT have achieved impressive success. The WHO goal of eliminating the disease by 2020 is now more realistic than ever.
The diagnostic landscape
Since 2006, FIND has collaborated with WHO and partners in research, industry, and government to develop user-friendly tests that enable early detection of cases and are appropriate for remote resource-limited settings.
At present, diagnosis of HAT requires 1) screening to identify suspects, 2) lab work to confirm the presence of the disease in suspects, and 3) ‘staging’ to verify whether the disease has advanced to the brain and what treatment is appropriate.
Current screening strategies require heavy logistics and their sensitivity is unsatisfactory. Only a small fraction of at-risk populations are screened and a significant number of cases go undetected. A first-generation rapid diagnostic test (RDT) is helping to address these challenges, but a better-quality, second-generation RDT that is easier to manufacture is needed.
Improved case confirmation and staging methods are also imperative. Currently, patients who are found positive for HAT with RDTs have to be confirmed because available treatments can cause serious side effects. Current methods for staging and confirmation of cure require an invasive and uncomfortable lumbar puncture and are either insufficiently accurate, labour intensive, or not widely used.
FIND has prioritized development of diagnostic solutions to improve screening and case confirmation of HAT, and to sustain elimination. These interventions include developing and introducing: i) highly accurate RDTs for screening HAT, ii) an RDT that detects both HAT and malaria, iii) improved microscopy tools, and iv) highly sensitive molecular methods for case confirmation.
To improve the impact of new diagnostic solutions, FIND simultaneously supports related policy, access and advocacy activities.