11 research outputs found
A targeted door-to-door strategy for sleeping sickness detection in low-prevalence settings in CĂŽte dâIvoire
Significant efforts to control human African trypanosomiasis (HAT) over the three past decades have resulted in drastic reductions of disease prevalence in CĂŽte dâIvoire. In this context, the costly and labor-intensive active mass screening strategy is no longer efficient. In addition to a more cost-effective passive surveillance system being implemented in this low-prevalence context, our aim was to develop an alternative targeted active screening strategy. In 2012, we carried out a targeted door-to-door (TDD) survey focused on the immediate vicinities of former HAT patients detected in the HAT focus of Bonon and compared the results to those obtained during classical active mass screening (AMS) surveys conducted from 2000 to 2012 in the same area. The TDD that provides a friendlier environment, inviting inhabitants to participate and gain awareness of the disease, detected significantly more HAT cases than the AMS. These results suggest that the TDD is an efficient and useful strategy in low-prevalence settings where very localized transmission cycles may persist and, in combination with passive surveillance, could help in eliminating HAT
A targeted door-to-door strategy for sleeping sickness detection in low-prevalence settings in CĂŽte dâIvoire
Significant efforts to control human African trypanosomiasis (HAT) over the three past decades have resulted in drastic reductions of disease prevalence in CĂŽte dâIvoire. In this context, the costly and labor-intensive active mass screening strategy is no longer efficient. In addition to a more cost-effective passive surveillance system being implemented in this low-prevalence context, our aim was to develop an alternative targeted active screening strategy. In 2012, we carried out a targeted door-to-door (TDD) survey focused on the immediate vicinities of former HAT patients detected in the HAT focus of Bonon and compared the results to those obtained during classical active mass screening (AMS) surveys conducted from 2000 to 2012 in the same area. The TDD that provides a friendlier environment, inviting inhabitants to participate and gain awareness of the disease, detected significantly more HAT cases than the AMS. These results suggest that the TDD is an efficient and useful strategy in low-prevalence settings where very localized transmission cycles may persist and, in combination with passive surveillance, could help in eliminating HAT
Reactivity to the Litat 1.3, 1.5 and 1.6 VAT according to the different PCR profiles.
<p>PCR profiles are given as follow: PCR TBR result/PCR TCF result/PCR TVW result. n = number of animals with the corresponding profile. Numbers on the top are the numbers of animal positives with Litat 1.3 and/or 1.5 TL or with LiTat 1.6 only.</p
Number of domestic animals sampled by species and foci.
<p>Number of domestic animals sampled by species and foci.</p
Immune trypanolysis (TL) results.
<p>Proportion of the LiTat 1.6 (4A), LiTat 1.3 (4B) and LiTat 1.5 (4C) TL positive results on the total sample collection for each host in the two foci. A significant difference between Bonon and Sinfra is indicated with a star.</p
The study areas and sites of animal sampling.
<p>A. Localization of the Bonon and Sinfra foci which reported the highest number of HAT cases diagnosed from 2000 to 2010 in CĂŽte dâIvoire. B. Localization of the last HAT cases diagnosed from 2011 to 2013 and the sites of domestic animals sampling in the Bonon and Sinfra foci. This figure was created by the mapping service of our team based at Institut Pierre Richet (BouakĂ©, CĂŽte dâIvoire) specifically for this manuscript.</p
Microsatellite genotyping results.
<p>Neighbor-joining tree (NJTree), based on Cavalli-Sforza and Ewards Chord distance, of the amplified microsatellite genotypes. Reference stocks are in bold. The unique monophyletic lineage corresponds to <i>Trypanosoma brucei gambiense</i> and is indicated above the corresponding branch. The presence of several missing genotypes prohibited the use of bootstraps. Bo = Bonon, Si = Sinfra, Tbg = <i>Trypanosoma brucei gambiense</i>, Tbg2 = <i>Trypanosoma brucei gambiense</i> group 2, Tbb = <i>Trypanosoma brucei brucei</i>, Tbrh = <i>Trypanosoma brucei rhodesiense</i>.</p
Parasitological and PCR results.
<p>Proportion of BCT (2A), <i>T</i>. <i>brucei</i> s.l. TBR-PCR (2B), <i>T</i>. <i>congolense</i> forest type TCF-PCR (2C) and <i>T</i>. <i>vivax</i> TVW-PCR (2D) positive results on the total sample collection for each host in the two foci. A significant difference between Bonon and Sinfra is indicated by a star.</p
Specificity of serological screening tests and reference laboratory tests to diagnose gambiense human African trypanosomiasis: a prospective clinical performance study
International audienceBackground Serological screening tests play a crucial role to diagnose gambiense human African trypanosomiasis (gHAT). Presently, they preselect individuals for microscopic confirmation, but in future âscreen and treatâ strategies they will identify individuals for treatment. Variability in reported specificities, the development of new rapid diagnostic tests (RDT) and the hypothesis that malaria infection may decrease RDT specificity led us to evaluate the specificity of 5 gHAT screening tests. Methods During active screening, venous blood samples from 1095 individuals from CĂŽte dâIvoire and Guinea were tested consecutively with commercial (CATT, HAT Sero- K -SeT, Abbott Bioline HAT 2.0) and prototype (DCN HAT RDT, HAT Sero- K -SeT 2.0) gHAT screening tests and with a malaria RDT. Individuals withââ„â1 positive gHAT screening test underwent microscopy and further immunological (trypanolysis with T.b. gambiense LiTat 1.3, 1.5 and 1.6; indirect ELISA/ T.b. gambiense ; T.b. gambiense inhibition ELISA with T.b. gambiense LiTat 1.3 and 1.5 VSG) and molecular reference laboratory tests (PCR TBRN3, 18S and TgsGP; SHERLOCK 18S Tids, 7SL Zoon , and TgsGP; Trypanozoon S 2 -RT-qPCR 18S2, 177T, GPI-PLC and TgsGP in multiplex ; RT-qPCR DT8, DT9 and TgsGP in multiplex). Microscopic trypanosome detection confirmed gHAT, while other individuals were considered gHAT free. Differences in fractions between groups were assessed by Chi square and differences in specificity between 2 tests on the same individuals by McNemar. Results One gHAT case was diagnosed. Overall test specificities ( n =â1094) were: CATT 98.9% (95% CI : 98.1â99.4%); HAT Sero- K -SeT 86.7% (95% CI : 84.5â88.5%); Bioline HAT 2.0 82.1% (95% CI : 79.7â84.2%); DCN HAT RDT 78.2% (95% CI : 75.7â80.6%); and HAT Sero- K -SeT 2.0 78.4% (95% CI : 75.9â80.8%). In malaria positives, gHAT screening tests appeared less specific, but the difference was significant only in Guinea for Abbott Bioline HAT 2.0 ( P =â0.03) and HAT Sero- K -Set 2.0 ( P =â0.0006). The specificities of immunological and molecular laboratory tests in gHAT seropositives were 98.7â100% ( n =â399) and 93.0â100% ( n =â302), respectively. Among 44 reference laboratory test positives, only the confirmed gHAT patient and one screening test seropositive combined immunological and molecular reference laboratory test positivity. Conclusions Although a minor effect of malaria cannot be excluded, gHAT RDT specificities are far below the 95% minimal specificity stipulated by the WHO target product profile for a simple diagnostic tool to identify individuals eligible for treatment. Unless specificity is improved, an RDT-based âscreen and treatâ strategy would result in massive overtreatment. In view of their inconsistent results, additional comparative evaluations of the diagnostic performance of reference laboratory tests are indicated for better identifying, among screening test positives, those at increased suspicion for gHAT