Prototype Rapid Diagnostic Test Detects Human African Trypanosomiasis

Early diagnosis and treatment of human African trypanosomiasis (HAT) is essential for safe and effective treatment but the tests used to screen suspected patients and populations at risk are difficult to implement in remote rural settings where the disease occurs.

The availability of simple, easy to use, instrument-free rapid diagnostic tests would improve screening and coverage of the population at risk and contribute to elimination of the disease. It would enable technicians with limited training and clinicians in emergency or medical wards to make rapid differential diagnosis for neurological syndromes or malaria-like illnesses.

Scientists at the Institute of Neuroepidemiology and Tropical Neurology (Limoges, France) and their African colleagues enrolled study participants from HAT endemic regions during both active and passive screening activities by teams of the national sleeping sickness control programs. Cases of HAT were defined as subjects in whom trypanosomes were demonstrated by microscopy in blood, lymph node aspirate or cerebral spinal fluid (CSF).

The test used in the study was the prototype SD BIOLINE HAT (Alere/Standard Diagnostics, Inc., Yongin-si, South Korea) which is an immunochromatographic test for qualitative detection of antibodies of all isotypes (immunoglobulin G (IgG), IgA and IgM). The rapid diagnostic test (RDT) has a nitrocellulose membrane strip with two regions (T1 and T2) that are pre-coated with two native variant surface glycoprotein (VSG) antigens from Trypanosoma brucei gambiense (VSG LiTat1.3 and VSG LiTat 1.5 respectively). It also has a procedural control line (C). The prototype RDTs were compared with the reference antibody detection screening test in current use, the card agglutination test for trypanosomiasis (CATT/T.b.gambiense).

In total, 14,818 participants were screened using both serological tests (9.5% in passive screening), and out of these 149 HAT cases were confirmed by parasitology. Among the 149 confirmed cases, 148 were positive by either CATT on whole blood and/or RDT, while one case was negative by both CATT whole blood and RDT, and was detected by CATT dilutions. The sensitivity and specificity of the prototype SD BIOLINE HAT was 89.3% and 94.6% respectively. The sensitivity and specificity of the CATT on whole blood were 94.0% and 95.9%, and of the CATT diluted 1/8 were 89.3% and 98.9% respectively.

The authors concluded that after further optimization, the prototype SD BIOLINE HAT could become an alternative to current screening methods in primary healthcare settings in remote, resource-limited regions where HAT typically occurs. The study was published on April 8, 2016, in the journal Public Library of Science Neglected Tropical Diseases.

Related Links:
Institute of Neuroepidemiology and Tropical Neurology
Standard Diagnostics