Impacts des évolutions démographiques et climatiques sur la répartition spatiale des hommes, des tsé-tsé et des trypanosomoses en Afrique de l’Ouest

Courtin, Fabrice; Sidibé, Issa; Rouamba, Jérémi; Jamonneau, Vincent; Gouro, Abdoulaye; Solano, Philippe

doi:10.1051/parasite/2009161003

Cited by 33 publications

(26 citation statements)

References 12 publications

(5 reference statements)

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“…morsitans submorsitans was captured by surveys conducted 20 years ago [11], but none was caught during the current surveys, or previous ones in the area [23]. This confirms its disappearance in places where human encroachment is high and where wildlife disappears, as reported elsewhere [24, 25]. …”

Section: Discussionsupporting

confidence: 85%

Adding tsetse control to medical activities contributes to decreasing transmission of sleeping sickness in the Mandoul focus (Chad)

Péka²,

et al. 2017

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BackgroundGambian sleeping sickness or HAT (human African trypanosomiasis) is a neglected tropical disease caused by Trypanosoma brucei gambiense transmitted by riverine species of tsetse. A global programme aims to eliminate the disease as a public health problem by 2020 and stop transmission by 2030. In the South of Chad, the Mandoul area is a persistent focus of Gambian sleeping sickness where around 100 HAT cases were still diagnosed and treated annually until 2013. Pre-2014, control of HAT relied solely on case detection and treatment, which lead to a gradual decrease in the number of cases of HAT due to annual screening of the population.MethodsBecause of the persistence of transmission and detection of new cases, we assessed whether the addition of vector control to case detection and treatment could further reduce transmission and consequently, reduce annual incidence of HAT in Mandoul. In particular, we investigated the impact of deploying ‘tiny targets’ which attract and kill tsetse. Before tsetse control commenced, a census of the human population was conducted and their settlements mapped. A pre-intervention survey of tsetse distribution and abundance was implemented in November 2013 and 2600 targets were deployed in the riverine habitats of tsetse in early 2014, 2015 and 2016. Impact on tsetse and on the incidence of sleeping sickness was assessed through nine tsetse monitoring surveys and four medical surveys of the human population in 2014 and 2015. Mathematical modelling was used to assess the relative impact of tsetse control on incidence compared to active and passive screening.FindingsThe census indicated that a population of 38674 inhabitants lived in the vicinity of the Mandoul focus. Within this focus in November 2013, the vector is Glossina fuscipes fuscipes and the mean catch of tsetse from traps was 0.7 flies/trap/day (range, 0–26). The catch of tsetse from 44 sentinel biconical traps declined after target deployment with only five tsetse being caught in nine surveys giving a mean catch of 0.005 tsetse/trap/day. Modelling indicates that 70.4% (95% CI: 51–95%) of the reduction in reported cases between 2013 and 2015 can be attributed to vector control with the rest due to medical intervention. Similarly tiny targets are estimated to have reduced new infections dramatically with 62.8% (95% CI: 59–66%) of the reduction due to tsetse control, and 8.5% (95% 8–9%) to enhanced passive detection. Model predictions anticipate that elimination as a public health problem could be achieved by 2018 in this focus if vector control and screening continue at the present level and, furthermore, there may have been virtually no transmission since 2015.ConclusionThis work shows that tiny targets reduced the numbers of tsetse in this focus in Chad, which may have interrupted transmission and the combination of tsetse control to medical detection and treatment has played a major role in reducing in HAT incidence in 2014 and 2015.

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Section: Discussionsupporting

confidence: 85%

Adding tsetse control to medical activities contributes to decreasing transmission of sleeping sickness in the Mandoul focus (Chad)

Péka²,

et al. 2017

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“…Cela confirme que, au contraire des glossines du groupe morsitans qui ont tendance à disparaître dès que les densités humaines augmentent (Reid et al, 2000), certaines espèces du groupe palpalis sont capables de s'adapter aux environnements péri-domestiques (Baldry, 1964), voire même aux grands centres urbains. En effet, cette espèce a été décrite dans diverses capitales (Bamako, Dakar) d'Afrique de l'Ouest (Challier, 1968;Courtin et al, 2009), ainsi que sa "cousine phylogénétique" G. fuscipes (Dyer et al, 2008) en Afrique Centrale (Brazzaville; Kinshasa) où une importante épidémie de THA a eu lieu récemment (Ebeja et al, 2003). Ces faits sont assez spectaculaires pour des insectes réputés fragiles, dont les taux de reproduction sont particulièrement faibles, et que l'on qualifie volontiers de "fossile vivant" et pourraient trouver leur explication dans la structure des populations de ces espèces et leur éclectisme alimentaire (Solano, 2008).…”

Section: Discussionunclassified

Chorologie et infection par les trypanosomes deGlossina palpalis palpalisdans la forêt du banco et ses reliques, abidjan (Côte d’ivoire)

Allou

Acapovi-Yao

Kaba³

et al. 2009

Parasite

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Summary : ECO-DISTRIBUTION AND TRYPANOSOMA INFECTION OF GLOSSINA PALPALIS PALPALIS IN THE BANCO FOREST OF AND ITS RELICS, ABIDJAN (CÔTE D'IVOIRE)In order to implement an anti-vector programme in the suburb of Abidjan (Côte d'Ivoire), investigations were conducted to assess the tsetse fly densities as well as infection with trypanosomes. Catches were carried out during the rainy season and dry season with Vavoua traps laid during four consecutive days in different sites (Banco forest, Abidjan zoological park, area of the University of Abobo-Adjamé). One species of tsetse fly (Glossina palpalis palpalis) and two species of trypanosomes (Trypanosoma congolense, T. vivax) have been revealed. The apparent density per trap per day (DAP) is very high in the zoological park, 54.8 tsetse fly/trap/day during the dry season and 28.1 during the rainy season. At the University of Abobo-Adjamé, the DAP is respectively 13.5 and 8.1 tsetse fly/trap/day during the rainy season, and in the dry season it is only 0.9 and 0.8 in the Banco Forest. The physiological age on all sites is as follows: 57.5 % of old parous, 39 % of young parous and 3.6 % of nulliparous in the rainy season. These proportions vary to 51.9 % of young parous, 47.1 % of old parous and 1 % of nulliparous in the dry season. The overall infection rate is estimated at 20.7 % in the rainy season and 20 % in the dry season. Statistical analysis have showed a significant difference in the distribution of infection rates. Résumé

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“…Finally, an increased relative importance of mechanical transmission in disturbed landscapes will also favour T. vivax, which is more easily mechanically transmitted (Desquesnes et al, 2009). It is worth noticing that sleeping sickness (Trypanosoma brucei gambiense) also disappeared from the Mouhoun River basin (Courtin et al, 2009). …”

Section: Population Age Composition and Nature Of Infectionsmentioning

confidence: 96%

Spatio-temporal distribution of tsetse and other biting flies in the Mouhoun River basin, Burkina Faso

Koné

N’Goran

Sidibé

et al. 2010

Medical and Veterinary Entomology

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In the Mouhoun River basin, Burkina Faso, the main vectors of African animal trypanosomoses are Glossina palpalis gambiensis Vanderplank and Glossina tachinoides Westwood (Diptera: Glossinidae), both of which are riverine tsetse species. The aim of our study was to understand the impact of landscape anthropogenic changes on the seasonal dynamics of vectors and associated trypanosomosis risk. Three sites were selected on the basis of the level of disturbance of tsetse habitats and predominant tsetse species: disturbed (Boromo, for G. tachinoides) and half-disturbed (Douroula for G. tachinoides and Kadomba for G. p. gambiensis). At each of these sites, seasonal variations in the apparent densities of tsetse and mechanical vectors and tsetse infection rates were monitored over 17 months. Tsetse densities differed significantly between sites and seasons. Of 5613 captured tsetse, 1897 were dissected; 34 of these were found to be infected with trypanosomes. The most frequent infection was Trypanosoma vivax (1.4%), followed by Trypanosoma congolense (0.3%) and Trypanosoma brucei (0.05%). The mean physiological age of 703 tsetse females was investigated to better characterize the transmission risk. Despite the environmental changes, it appeared that tsetse lived long enough to transmit trypanosomes, especially in half-disturbed landscapes. A total of 3021 other biting flies from 15 species (mainly Tabanidae and Stomoxyinae) were also caught: their densities also differed significantly among sites and seasons. Their relative importance regarding trypanosome transmission is discussed; the trypanosomosis risk in cattle was similar at all sites despite very low tsetse densities (but high mechanical vector densities) in one of them.

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Impacts des évolutions démographiques et climatiques sur la répartition spatiale des hommes, des tsé-tsé et des trypanosomoses en Afrique de l’Ouest

Cited by 33 publications

References 12 publications

Adding tsetse control to medical activities contributes to decreasing transmission of sleeping sickness in the Mandoul focus (Chad)

Adding tsetse control to medical activities contributes to decreasing transmission of sleeping sickness in the Mandoul focus (Chad)

Chorologie et infection par les trypanosomes deGlossina palpalis palpalisdans la forêt du banco et ses reliques, abidjan (Côte d’ivoire)

Spatio-temporal distribution of tsetse and other biting flies in the Mouhoun River basin, Burkina Faso

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