A targeted door-to-door strategy for sleeping sickness detection in low-prevalence settings in Côte d’Ivoire

Significant efforts to control human African trypanosomiasis (HAT) over the three past decades have resulted in drastic reductions of disease prevalence in Côte d’Ivoire. 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 Côte d’Ivoire

Significant efforts to control human African trypanosomiasis (HAT) over the three past decades have resulted in drastic reductions of disease prevalence in Côte d’Ivoire. 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 Côte d’Ivoire. 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 (Bouaké, Côte d’Ivoire) 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