Assessment of Recombinant HAT-RDT Specificity

Overview

Human African trypanosomiasis HAT, or sleeping sickness, is a tropical disease caused mainly by the parasite Trypanosoma brucei gambiense (gHAT). After a severe epidemic in the 1990s, the World Health Organization (WHO) now targets elimination of transmission of gHAT by the year 2030, which heavily relies on its diagnosis and treatment. Traditional screening tests (like CATT or rapid diagnostic tests (RDTs)) are based on the detection of antibodies against the parasite using native antigens, which are costly and dangerous to produce. New serological tests, using recombinant antigens, have been developed, but little is known about their field performance. The primary objective of this study is to assess the specificity of the newly-developed recombinant RDTs, since it will become very relevant as we move forward towards a screen\&treat strategy. We will also compare the diagnostic accuracy and overall performance of iELISA and molecular testing.

This prospective study will follow two different mobile units as they go on their routine screening of the gHAT endemic population. Study participants will be enrolled during the routine screening, and after providing informed consent, they will be asked for a 4.5 ml venous blood sample. The three RDTs (HAT Sero-K-SeT, rHAT Sero-K-SeT, Bioline HAT 2.0) and CATT will be performed on site, while part of the sample will be mixed with DNA/RNA Shield for molecular analysis and the rest will be left to decant, to collect plasma for iELISA and TL. Confirmatory tests will be performed in the field on any seropositive individual. Should any case be confirmed, treatment will be offered, free of charge, following PNLTHA guidelines. The obtained data will allow for a very precise estimation of the specificity of the newly developed recombinant RDTs. This study does not aim to determine the sensitivity of these tests since, due to the very low prevalence, the chance of having sufficient seropositive samples and/or finding a true case are very slim. The diagnostic performance of iELISA and novel molecular tests will also be determined.

Conditions