Mapping African Animal Trypanosomosis risk from the sky

Bouyer, Jérémy; Guerrini, Laure; Desquesnes, Marc; Rocque, Stéphane De La; Cuisance, Dominique

doi:10.1051/vetres:2006025

Cited by 47 publications

(43 citation statements)

References 18 publications

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“…These results are in accordance with observations in other sites of the northern tsetse belt in West Africa (Bouyer et al, 2006;Guerrini & Bouyer, 2007) and might be due to a lower intrinsic vectorial capacity of G. palpalis gambiensis for T. congolense in comparison with e.g. Glossina morsitans submorsitans Newstead or Glossina tachinoïdes Westwood (Reifenberg et al, 2008), two species common in West Africa but absent in the study area.…”

Section: Discussionsupporting

confidence: 92%

“…The absence of a correlation between tsetse presence and density, the parasitological prevalence of both parasites and the serological prevalence of T. congolense is probably related to the very low values of the latter three parameters. Moreover, apparent fly density is not a good risk indicator and should be multiplied by tsetse infectious rate to better represent cyclical transmission (Bouyer et al, 2006;Guerrini & Bouyer, 2007). However, the importance of cyclical transmission of AAT in the study area is obvious from the presented results, even if evidence exists that T. congolense and T. vivax can also be transmitted mechanically by biting flies (Desquesnes et al, 2009;Desquesnes & Dia, 2003a, b, 2004.…”

Section: Discussionmentioning

confidence: 99%

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The prevalence of African animal trypanosomoses and tsetse presence in Western Senegal

Seck

Bouyer

Sall³

et al. 2010

Parasite

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(Mulligan, 1970) which is widespread in sub-Saharan Africa (Itard et al., 2003). AAT is Summary:In 2005, the Government of Senegal initiated a tsetse eradication campaign in the Niayes and La Petite Côte aiming at the removal of African Animal Trypanosomosis (AAT), which is one of the main constraints to the development of more effective cattle production systems. The target area has particular meteorological and ecological characteristics that provide great potential for animal production, but it is unfortunately still infested by the riverine tsetse species Glossina palpalis gambiensis Vanderplank (Diptera: Glossinidae). The tsetse project in Senegal has adopted an areawide integrated pest management (AW-IPM) approach that targets the entire tsetse population within a delimited area. During the first phase of the programme, a feasibility study was conducted that included the collection of entomological, veterinary, population genetics, environmental and socio-economic baseline data. This paper presents the parasitological and serological prevalence data of AAT in cattle residing inside and outside the tsetse-infested areas of the target zone prior to the control effort. At the herd level, a mean parasitological prevalence of 2.4 % was observed, whereas a serological prevalence of 28.7 %, 4.4 %, and 0.3 % was obtained for Trypanosoma vivax, T. congolense and T. brucei brucei, respectively. The observed infection risk was 3 times higher for T. congolense and T. vivax in the tsetse-infested than in the assumed tsetse-free areas. Moreover, AAT prevalence decreased significantly with distance from the nearest tsetse captured which indicated that cyclical transmission of the parasites by tsetse was predominant over mechanical transmission by numerous other biting flies present. The importance of these results for the development of a control strategy for the planned AW-IPM campaign is discussed.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

The prevalence of African animal trypanosomoses and tsetse presence in Western Senegal

Seck

Bouyer

Sall³

et al. 2010

Parasite

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“…Since ADT distributions are generally not normal but aggregated (Bouyer 2006;Bouyer et al 2006), the cor- relations between tsetse average densities and the total number of pigs in buffers of 100, 200, 500 and 1,000 m around the traps were investigated at the trapping site level using Kendall's rank correlation tau (Hollander & Wolfe, 1973 (Fig. 1).…”

Section: Statisticsmentioning

confidence: 99%

Tsetse elimination: its interest and feasibility in the historical sleeping sickness focus of Loos islands, Guinea

Kagbadouno¹,

Camara²,

Bouyer

et al. 2009

Parasite

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Summary :Guinea is the West African country which is currently the most prevalent for sleeping sickness. The littoral area is the region where most of the recent sleeping sickness cases have been described, especially the mangrove sleeping sickness foci of Dubreka and Boffa where Glossina palpalis gambiensis is the vector. Loos islands constitute a small archipelago 5 km apart from the capital, Conakry. Medical, animal, and entomological surveys were implemented in these islands in Oct-Nov 2006. No pathogenic trypanosomes were found in these surveys. The locally very high tsetse densities (up to more than 100 tsetse/trap/day) linked to pig rearing, constitute a high potential risk for humans (taking into account populations movements with neighboring active sleeping sickness foci of the Guinea littoral, and the history of sleeping sickness on these islands), and for the economically important pig rearing, as well as a danger for tourism. This situation, associated to the possibility of elimination of these tsetse populations due to low possibility of reinvasion, led the National Control Program to launch a tsetse elimination project following an "area wide" strategy for the first time in West Africa, which participates in the global objective of the PATTEC (Pan African Tsetse and Trypanosomosis Eradication Campaign). Résumé

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“…In domestic animals, although the prevalence of the disease varies between populations and localities, trypanosomosis generally presents as an endemic disease, with a widespread presence in livestock populations across the tsetse-infested area of sub-Saharan Africa. The use of GIS and satellite imagery to map animal trypanosomosis has been explored (Hendrickx et al, 2000;de la Rocque et al, 2005;Bouyer et al 2006;) and recently work has begun on mapping the distribution of animal trypanosomosis as well as tsetse at a continental level (Cecchi et al, , 2015.…”

Section: Introductionmentioning

confidence: 99%

Mapping the benefit-cost ratios of interventions against bovine trypanosomosis in Eastern Africa

Shaw

Wint

Cecchi³

et al. 2015

Preventive Veterinary Medicine

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This study builds upon earlier work mapping the potential benefits from bovine trypanosomosis control and analysing the costs of different approaches. Updated costs were derived for five intervention techniques: trypanocides, targets, insecticide-treated cattle, aerial spraying and the release of sterile males. Two strategies were considered: continuous control and elimination. For mapping the costs, cattle densities, environmental constraints, and the presence of savannah or riverine tsetse species were taken into account. These were combined with maps of potential benefits to produce maps of benefit-cost ratios. The results illustrate a diverse picture, and they clearly indicate that no single technique or strategy is universally profitable. For control using trypanocide prophylaxis, returns are modest, even without accounting for the risk of drug resistance but, in areas of low cattle densities, this is the only approach that yields a positive return. Where cattle densities are sufficient to support it, the use of insecticidetreated cattle stands out as the most consistently profitable technique, widely achieving benefit-cost ratios above 5. In parts of the high-potential areas such as the mixed farming, high-oxen-use zones of western Ethiopia, the fertile crescent north of Lake Victoria and the dairy production areas in western and central Kenya, all tsetse control strategies achieve benefit-cost ratios from 2 to over 15, and for elimination strategies, ratios from 5 to over 20. By contrast, in some areas, notably where cattle densities are below 20 per km 2 , the costs of interventions against tsetse match or even outweigh the benefits, especially for control scenarios using aerial spraying or the deployment of targets where both savannah and riverine flies are present. If the burden of human African trypanosomosis were factored in, the benefit-cost ratios of some of the low-return areas would be considerably increased. Comparatively, elimination strategies give rise to higher benefit-cost ratios than do those for continuous control. However, the costs calculated for elimination assume problem-free, large scale operations, and they rest on the outputs of entomological models that are difficult to validate in the field. Experience indicates that the conditions underlying successful and sustained elimination campaigns are seldom met. By choosing the most appropriate thresholds for benefit-cost ratios, decision-makers and planners can use the maps to define strategies, assist in prioritising areas for intervention, and help choose among intervention techniques and approaches. The methodology would have wider applicability in analysing other disease constraints with a strong spatial component.

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Mapping African Animal Trypanosomosis risk from the sky

Cited by 47 publications

References 18 publications

The prevalence of African animal trypanosomoses and tsetse presence in Western Senegal

The prevalence of African animal trypanosomoses and tsetse presence in Western Senegal

Tsetse elimination: its interest and feasibility in the historical sleeping sickness focus of Loos islands, Guinea

Mapping the benefit-cost ratios of interventions against bovine trypanosomosis in Eastern Africa

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