Abstract
BACKGROUND: Accurate diagnosis is essential for achieving the 2030 goal of eliminating gambiense human African trypanosomiasis (gHAT) transmission. In recent years, novel screening and confirmatory laboratory tests, including rapid diagnostic tests incorporating recombinant antigens (2nd generation RDTs), an inhibition ELISA (iELISA) and RT-qPCR, have been developed. However, data on their diagnostic performance remain limited. This study aimed to evaluate the specificity of these newly developed tests, with particular emphasis on 2nd generation RDTs. METHODS: During routine mobile team screening rounds in the Democratic Republic of the Congo, all consenting individuals aged ≥ 12 years provided a venous blood sample to screen for gHAT by Card Agglutination Test for Trypanosomiasis (CATT) and three RDTs (Abbott Bioline HAT 2.0, HAT Sero K-SeT and HAT Sero K-SeT 2.0). The remaining blood samples were shipped to the Institut National de Recherche Biomédicale, for further testing by iELISA, immune trypanolysis and RT-qPCR. gHAT cases were defined by the direct visualization of trypanosomes in blood or lymph. RESULTS: A total of 1503 participants were recruited in the Kwilu and Lomami provinces. Among the screening tests, CATT demonstrated the highest specificity at 98.3% (95% CI 97.6-99.0%). followed by HAT Sero K-SeT at 91.0% (95% CI 89.5-92.4%), HAT Sero K-SeT 2.0 at 87.1% (95% CI 85.4-88.8%) and Abbott Bioline HAT 2.0 at 76.4% (95% CI 74.3-78.6%). Among the laboratory tests, immune trypanolysis achieved a specificity of 97.8% (95% CI 97.1-98.6%) while iELISA reached 96.1% (95% CI 95.1-97.1%). RT-qPCR had the highest specificity at 99.9% (95% CI 99.7-100%). None of the RDTs met the 95% specificity threshold as recommended by the WHO target product profiles for gHAT, emphasizing the need for further improvements in their specificity. TRIAL REGISTRATION: The trial was retrospectively registered under NCT05637632 in clinicaltrials.gov on November 24, 2022.