The origins of a new  Trypanosoma brucei rhodesiense  sleeping sickness outbreak in eastern Uganda

Fèvre, Eric M.; Coleman, P. G.; Odiit, M.; Magona, J.W.; Welburn, Susan C.; Woolhouse, Mark

doi:10.1016/s0140-6736(01)05778-6

Cited by 189 publications

(179 citation statements)

References 7 publications

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“…Turning to the disease, the human form (sleeping sickness) is characterized by a pronounced focal nature, with the distribution of endemic foci remaining remarkably stable over the last century (Simarro et al, 2010) with a few notable exceptions (e.g. Fèvre et al, 2001). Recently, systematic data collation and mapping have made it possible to represent the current distribution of human African trypanosomosis with high accuracy (Cecchi et al, 2009;Simarro et al, 2010) and to assess the population at risk (Simarro et al, 2012).…”

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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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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“…in endemic areas (Angus 1996;Fervre, Coleman, Odiit, Magona, Welburn & Woolhouse 2001). This is due to an incidence of up to 20 % of T. b. rhodesiense in cattle in endemic areas (Hide, Angus, Holmes, Maudlin & Welburn 1998).…”

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confidence: 99%

Occurrence of multiple drug resistance in <i>Trypanosoma brucei rhodesiense</i> isolated from sleeping sickness patients

Kagira

Maina²

2007

Onderstepoort J Vet Res

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The occurrence of cross-resistance among melarsoprol-resistant Trypanosoma brucei rhodesiense isolates was investigated in this study. The isolates, T. b. rhodesiense KETRI 237, 2538, 1992, 2709, 2694 and 3530, had been obtained from sleeping sickness patients in Kenya and Uganda between 1960 and 1985. Five groups consisting of six mice each were inoculated intraperitoneally with 105 parasites of each isolate, and 24 h later treated with either melarsoprol, homidium chloride, diminazene aceturate or isometamidium chloride. The control group comprised infected but untreated mice. The mice were monitored for cure for a period of 60 days post-treatment. The mean prepatent period in the control mice was 5 days while the mean survival period was 22 days. Five of the stabilates, KETRI 237, 2538, 2709, 2694, and 3530, were confirmed to be melarsoprol resistant. Cross-resistance was observed, with the majority of the isolates being resistant to homidium chloride (5/6) and diminazene aceturate (5/6), but all were sensitive to isometamidium chloride (6/6). However T. b. rhodesiense KETRI 1992, which was previously considered as melarsoprol resistant, was sensitive to all the drugs tested. In conclusion, our study has revealed the existence of cross-resistance among the melarsoprol resistant isolates which could only be cured by isometamidium.

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“…This can be a particular challenge in developing countries in which good quality maps of residential areas are often not available [54]. Several investigations of outbreaks in such settings conducted field surveys and used Global Positioning Systems (GPS) to accurately record patient residence or risk factor locations [30,35,43,46,55,56]. However, this is a time-and cost-intensive approach and will not always be feasible.…”

Section: Discussionmentioning

confidence: 99%

“…Fevre and colleagues, for example, assessed clustering of cases of trypanosomiasis under the hypothesis that a cattle market was the source of the outbreak [35]. A significant cluster encompassing the location of the market was detected using the spatiotemporal scan statistic, supporting this theory.…”

Section: Evaluating Hypotheses and Drawing Conclusionmentioning

confidence: 93%

Spatial methods for infectious disease outbreak investigations: systematic literature review

et al. 2015

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Investigations of infectious disease outbreaks are conventionally framed in terms of person, time and place. Although geographic information systems have increased the range of tools available, spatial analyses are used relatively infrequently. We conducted a systematic review of published reports of outbreak investigations worldwide to estimate the prevalence of spatial methods, describe the techniques applied and explore their utility. We identified 80 reports using spatial methods published between 1979 and 2013, ca 0.4% of the total number of published outbreaks. Environmental or waterborne infections were the most commonly investigated, and most reports were from the United Kingdom. A range of techniques were used, including simple dot maps, cluster analyses and modelling approaches. Spatial tools were usefully applied throughout investigations, from initial confirmation of the outbreak to describing and analysing cases and communicating findings. They provided valuable insights that led to public health actions, but there is scope for much wider implementation and development of new methods.

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The origins of a new Trypanosoma brucei rhodesiense sleeping sickness outbreak in eastern Uganda

Cited by 189 publications

References 7 publications

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

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

Occurrence of multiple drug resistance in <i>Trypanosoma brucei rhodesiense</i> isolated from sleeping sickness patients

Spatial methods for infectious disease outbreak investigations: systematic literature review

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