Need of entomological criteria to assess zero transmission of gambiense HAT

Solano, Philippe

doi:10.1371/journal.pntd.0009235

Cited by 6 publications

(8 citation statements)

References 27 publications

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“…A total of 30 traps (15 NGU and 15 bi-conical) were installed at roughly 4/km2 for two days in each grid depending on vegetation type, drainage system, accessibility, and human activities (settlements or cultivated land). All traps were baited with cow urine dispensed at 100 mg/hr from plastic bottles and acetone, dispensed at 500 mg/h from glass bottles and greased to prevent ants from damaging the catch [14]. Traps were checked after 12 hours, and the ies were removed from the trap.…”

Section: Tsetse Fly Samplingmentioning

confidence: 99%

“…The transmission of Trypanosoma vivax is cyclical (transmitted by the tsetse y) and mechanical (by tabanidae and stomoxys). T. evansi in camels and T. equiperdum in horses are transmitted by the tsetse y, Stomoxys and Tabanus, but mechanical transmission to domestic animals [14].…”

Section: Introductionmentioning

confidence: 99%

“…Cattle movement is a threat for the disease transmission, spread, and occurrences of outbreaks [14].…”

Section: Introductionmentioning

confidence: 99%

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A potential Entomological and epidemiological drivers for Reemergence of Human African Trypanosomiasis in Ethiopia after 55 Years

Waldetensai

Abose

Getachew

et al. 2023

Preprint

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Background: Sleeping Sickness, Human African Trypanosomiasis (HAT) is a vector- borne disease caused by Trypanosoma brucei (T.b). Sleeping sickness in Ethiopia was reported in 1967 for the first time. Recently in Southern parts of Ethiopia, in August 2022, five (5) cases of sleeping sickness (T. b. rhodesiense) were confirmed. Following this outbreak, the current investigation was aimed to identify the entomological and epidemiological drivers for the reemergence of HAT outbreak and recommend appropriate interventions. Methods: A cross sectional study design with descriptive data analysis was used. Tsetse fly collection and blood samples from cattle Animal were taken. NGU and bio-conical traps were used to determine the distribution (density and abundance) of the vector. About 10μl of blood was collected from the marginal ear vein of 301 cattle animals using the heparinized microhematocrit capillary. The parasite detection was carried out through vector dissection under binocular stereo-microscope (magnification of 60X) and microscopic examination from serum of Animals using the Buffy coat method. Results: A total of 329 tsetse flies were captured and identified to Glosina (G.) palidipes 259 (60.4%) and Glossina fuscipes 70 (16.3%). 188 (51.1%) of tsetse flies were collected from Dembagofa with 94 apparent density. Among all captured Tsetse fly, 39 (11.8%) of Tsetse were fed with high female apparent density in eachecological variation: wood land (51), Bush land (20) and grass land (11). Overall, the apparent density of tsetse fly was high in Wood land (93): G. pallidipes (76.5) and Bush land (36.5). Among all examine cattles for the presence of parasite, 9 cattles were detected positive with an overall prevalence of 3%. T. congolense 6 (2%) and T. vivax 1 (0.3%) with 2 (0.7%) suspected brucei. The parasite prevalence Trypanosoma was 4 (4.6%) in poor body a condition (Bcs) cattle. The animals in age range 5 - 9 years were infected high with 7 (5.3%) prevalence. Conclusion: The current study revealed that there are high-risk factors that predispose the community to Human African Trypanosomiasis (HAT) due to the presence of two different species of Tsetse flies and many animal reservoirs. The transmissions of Human African trypanosomiasis (HAT) are related to environmental, Vector, and human factors. Further geographically expanded investigation should be conducted throughout the country.

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Section: Tsetse Fly Samplingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A potential Entomological and epidemiological drivers for Reemergence of Human African Trypanosomiasis in Ethiopia after 55 Years

Waldetensai

Abose

Getachew

et al. 2023

Preprint

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“…The transmission of Trypanosoma vivax is cyclical (transmitted by the tsetse fly) and mechanical (by tabanidae and stomoxys). T. evansi in camels and T. equiperdum in horses are transmitted by the tsetse fly, Stomoxys and Tabanus, but mechanical transmission to domestic animals [14].…”

Section: Introductionmentioning

confidence: 99%

“…Cattle movement is a threat for the disease transmission, spread, and occurrences of outbreaks [14]. Wildlife hosts: bushbucks (Tragelaphusscriptus), impalas (Aepycerosmelampus), lions (Pantheraleo), zebras (Equus quagga boehma), warthogs (Phacocoerusafricanus), and duikers (Sylvicapragrimmia) carry the human-infective zoonotic trypanosome strain T. b. rhodesiense [13].…”

Section: Introductionmentioning

confidence: 99%

A Potential Entomological and Epidemiological Drivers for Reemergence of Human African Trypanosomiasis in Ethiopia after 55 Years

Waldetensai¹,

Abose²,

Abebe³

et al. 2023

Preprint

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Background: Sleeping Sickness, Human African Trypanosomiasis (HAT) is a vector- borne disease caused by Trypanosoma brucei (T.b). Sleeping sickness in Ethiopia was reported in 1967 for the first time. Recently in Southern parts of Ethiopia, in August 2022, five (5) cases of sleeping sickness (T. b. rhodesiense) were confirmed. Following this outbreak, the current investigation was aimed to identify the entomological and epidemiological drivers for the reemergence of HAT outbreak and recommend appropriate interventions.Methods: A cross sectional study design with descriptive data analysis was used. Tsetse fly collection and blood samples from cattle Animal were taken. NGU and bio-conical traps were used to determine the distribution (density and abundance) of the vector. About 10μl of blood was collected from the marginal ear vein of 301 cattle animals using the heparinized microhematocrit capillary. The parasite detection was carried out through vector dissection under binocular stereo-microscope (magnification of 60X) and microscopic examination from serum of Animals using the Buffy coat method. Results: A total of 329 tsetse flies were captured and identified to Glosina (G.) palidipes 259 (60.4%) and Glossina fuscipes 70 (16.3%). 188 (51.1%) of tsetse flies were collected from Dembagofa with 94 apparent density. Among all captured Tsetse fly, 39 (11.8%) of Tsetse were fed with high female apparent density in eachecological variation: wood land (51), Bush land (20) and grass land (11). Overall, the apparent density of tsetse fly was high in Wood land (93): G. pallidipes (76.5) and Bush land (36.5). Among all examine cattles for the presence of parasite, 9 cattles were detected positive with an overall prevalence of 3%. T. congolense 6 (2%) and T. vivax 1 (0.3%) with 2 (0.7%) suspected brucei. The parasite prevalence Trypanosoma was 4 (4.6%) in poor body a condition (Bcs) cattle. The animals in age range 5 - 9 years were infected high with 7 (5.3%) prevalence. Conclusion: The current study revealed that there are high-risk factors that predispose the community to Human African Trypanosomiasis (HAT) due to the presence of two different species of Tsetse flies and many animal reservoirs. The transmissions of Human African trypanosomiasis (HAT) are related to environmental, Vector, and human factors. Further geographically expanded investigation should be conducted throughout the country.

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Impact of a national tsetse control programme to eliminate Gambian sleeping sickness in Uganda: a spatio-temporal modelling study

Longbottom,

Esterhuizen,

Hope

et al. 2024

Preprint

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IntroductionTsetse flies (Glossina) transmitTrypanosoma brucei gambiensewhich causes gambiense human African trypanosomiasis (gHAT). As part of national efforts to eliminate gHAT as a public health problem, Uganda implemented a large-scale programme of deploying Tiny Targets, which comprise panels of insecticide-treated material which attract and kill tsetse. At its peak, the programme was the largest tsetse control operation in Africa. Here, we quantify the impact of Tiny Targets and environmental changes on the spatial and temporal patterns of tsetse abundance across north-western Uganda.MethodsWe leverage a 100-month longitudinal dataset detailingGlossina fuscipes fuscipescatches from monitoring traps between October 2010 and December 2019 within seven districts in north-western Uganda. We fitted a boosted regression tree model assessing environmental suitability which was used alongside Tiny Target data to fit a spatio-temporal geostatistical model predicting tsetse abundance across our study area (∼16,000 km2). We used the spatio-temporal model to quantify the impact of Tiny Targets and environmental changes on the distribution of tsetse, alongside metrics of uncertainty.ResultsEnvironmental suitability across the study area remained relatively constant over time, with suitability being driven largely by elevation and distance to rivers. By performing a counterfactual analysis using the fitted spatio-temporal geostatistical model we show that deployment of Tiny Targets across an area of 4000 km2reduced the overall abundance of tsetse to low levels (median daily catch = 1.1 tsetse/trap, IQR = 0.85-1.28) with no spatial-temporal locations having high (>10 tsetse/trap/day) numbers of tsetse compared to 18% of locations for the counterfactual.ConclusionsIn Uganda, Tiny Targets reduced the abundance ofG. f. fuscipesand maintained tsetse populations at low levels. Our model represents the first spatio-temporal model investigating the effects of a national tsetse control programme. The outputs provide important data for informing next steps for vector-control and surveillance.Key questionsWhat is already known on this topic?Small panels of insecticide-treated fabric, called Tiny Targets, are used to attract, and kill riverine tsetse, the vectors ofT. b. gambiensewhich causes gambiense human African trypanosomiasis (gHAT). In large-scale (250-2000 km2) trials conducted in five countries, deployment of Tiny Targets reduced the densities of tsetse by between 60 and >90%.What this study addsWe report an analysis of, and data from, a large-scale (∼4,000km2) national tsetse control programme, implemented in Uganda to eliminate gHAT as a public health problem. We found that Tiny Targets reduced tsetse abundance across the study period (2011-2019) and maintained densities at low (<1 tsetse/trap/day) levels. We produce maps which detail spatial variances in tsetse abundance in response to vector control.How this study might affect research, practice, or policyIn 2022, Uganda received validation from the World Health Organisation (WHO) that it had eliminated gHAT as a public health problem. The large-scale deployment of Tiny Targets contributed to this achievement. Our findings provide evidence that Tiny Targets are an important intervention for other countries aiming to eliminate gHAT.

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Need of entomological criteria to assess zero transmission of gambiense HAT

Cited by 6 publications

References 27 publications

A potential Entomological and epidemiological drivers for Reemergence of Human African Trypanosomiasis in Ethiopia after 55 Years

A potential Entomological and epidemiological drivers for Reemergence of Human African Trypanosomiasis in Ethiopia after 55 Years

A Potential Entomological and Epidemiological Drivers for Reemergence of Human African Trypanosomiasis in Ethiopia after 55 Years

Impact of a national tsetse control programme to eliminate Gambian sleeping sickness in Uganda: a spatio-temporal modelling study

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