b. gambiense parasite
in patients’ blood. Despite its utility and its high specificity and sensitivity (95% and 87–98%, respectively), it is not considered a diagnostic gold standard . Decreased accuracy of the CATT has been reported in some foci where particular strains of trypanosomes are present, as well as false positive results due to cross-reactions with antibodies to other parasites  and . Serological screening is followed by parasitological examination of body fluids for the detection of trypanosomes. The different methods of parasite detection in blood, such as microhaematocrit centrifugation (mHCT) or mini-anion exchange centrifugation SB203580 purchase (mAECT), have been reviewed elsewhere . However, parasitological tools are often not sensitive enough to detect parasites which may be present in patients’ body fluids in low numbers  and . Furthermore, the lower parasitemia typical of T. b. gambiense, compared to T. b. rhodesiense, might be responsible for the missed
diagnosis of 20–30% of T. b. gambiense cases . These limitations highlight the need for new tools to improve the screening and diagnosis of sleeping sickness. In order to improve efficacy in detecting HAT seropositive cases, see more alternatives to the CATT have been proposed. The test that has shown the highest potential as a new mass population-screening tool is the Latex/T. b. gambiense (Latex/T.b.g.). Like the CATT, this test detects antibodies against the parasite in patients’ blood through an agglutination reaction. The main advantage of Latex/T.b.g. is the detection of three different variant antigen types: LiTat 1.3, 1.5 and 1.6 , while the CATT detects only LiTat 1.3. As a consequence, Latex/T.b.g. produces fewer false negative results, but a decreased sensitivity has been reported
in some foci characterized by a high expression of LiTat 1.3 . However, the increased number of antigen targets did not solve the problem of false positives due to cross-reactions with other parasites. Contradictory results have been reported by different studies comparing Latex/T.b.g. and the CATT, or the standard CATT with improved versions of the same test (i.e. micro-CATT, CATT-EDTA) PJ34 HCl  ,  and . Recently, new antibody-based rapid assays, not requiring a cold chain, have been developed for the serological diagnosis of T. b. gambiense HAT: HAT SERO K-SeT, HAT Sero-Strip  and SD BIOLINE HAT (http://www.finddiagnostics.org/media/press/121206.html). Two of these promising tools – HAT SERO K-SeT and SD BIOLINE HAT, both developed as lateral flow assays – are currently under field evaluation in the Democratic Republic of the Congo. A diagnostic test based on the detection of parasite antigens, rather than antibodies developed by the host against the invading pathogens, would represent an efficient alternative and a substantial gain in terms of specificity.