Modeling the Control of Trypanosomiasis Using Trypanocides or Insecticide-Treated Livestock

Hargrove, John W.; Ouifki, Rachid; Kajunguri, Damian; Vale, G. A.; Torr, Stephen J.

doi:10.1371/journal.pntd.0001615

Cited by 64 publications

(78 citation statements)

References 45 publications

(66 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Similarly, it could have been as a result of higher challenge of T.vivax and T.congolense since these trypanosome species were detected in much higher proportions 9 months before intervention. This implies that control of nagana ( T.vivax and T.congolense ) in areas where tsetse mainly feed on cattle would require increasing village RAP herd coverage up to 50–75% as previously suggested [45]. In the current situation where dose response is distorted probably due to the differences in village level challenge, trypanosome transmission rates and management practices, initial treatment of all cattle in the intervention area with a curative trypanocide to reduce parasitaemia would leverage control by denying tsetse of trypanosomes to transmit [46].…”

Section: Discussionmentioning

confidence: 82%

Improvements on Restricted Insecticide Application Protocol for Control of Human and Animal African Trypanosomiasis in Eastern Uganda

et al. 2014

View full text Add to dashboard Cite

BackgroundAfrican trypanosomes constrain livestock and human health in Sub-Saharan Africa, and aggravate poverty and hunger of these otherwise largely livestock-keeping communities. To solve this, there is need to develop and use effective and cheap tsetse control methods. To this end, we aimed at determining the smallest proportion of a cattle herd that needs to be sprayed on the legs, bellies and ears (RAP) for effective Human and Animal African Trypanosomiasis (HAT/AAT) control.Methodology/Principal findingCattle in 20 villages were ear-tagged and injected with two doses of diminazene diaceturate (DA) forty days apart, and randomly allocated to one of five treatment regimens namely; no treatment, 25%, 50%, 75% monthly RAP and every 3 month Albendazole drench. Cattle trypanosome re-infection rate was determined by molecular techniques. ArcMap V10.3 was used to map apparent tsetse density (FTD) from trap catches. The effect of graded RAP on incidence risk ratios and trypanosome prevalence was determined using Poisson and logistic random effect models in R and STATA V12.1 respectively. Incidence was estimated at 9.8/100 years in RAP regimens, significantly lower compared to 25.7/100 years in the non-RAP regimens (incidence rate ratio: 0.37; 95% CI: 0.22–0.65; P<0.001). Likewise, trypanosome prevalence after one year of follow up was significantly lower in RAP animals than in non-RAP animals (4% vs 15%, OR: 0.20, 95% CI: 0.08–0.44; P<0.001). Contrary to our expectation, level of protection did not increase with increasing proportion of animals treated.Conclusions/significanceReduction in RAP coverage did not significantly affect efficacy of treatment. This is envisaged to improve RAP adaptability to low income livestock keepers but needs further evaluation in different tsetse challenge, HAT/AAT transmission rates and management systems before adopting it for routine tsetse control programs.

show abstract

Section: Discussionmentioning

confidence: 82%

Improvements on Restricted Insecticide Application Protocol for Control of Human and Animal African Trypanosomiasis in Eastern Uganda

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Where individual villages, or even more so, only individuals within villages treat their own cattle, higher numbers will need to be treated to achieve the same level of tsetse control. More information on this is emerging from field work (Muhanguzi et al, 2014) and modelling (Hargrove et al, 2012, Kajunguri et al, 2014.…”

Section: Discussionmentioning

confidence: 99%

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

Shaw

Wint

Cecchi³

et al. 2015

Preventive Veterinary Medicine

View full text Add to dashboard Cite

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.

show abstract

“…When properly applied, chemotherapy along with vector control becomes a very strong method of controlling trypanosomosis [49,50]. In general Diminazene aceturate (Berenil), Homidium chloride (Novidium) and Clinical and conventional parasitological diagnostic techniques are commonly used to detect trypanosome infections in African countries due to their simplicity [30,40].…”

Section: Villagementioning

confidence: 99%

Molecular Identification of Trypanosome Species in Cattle of the Mikumi Human/Livestock/Wildlife Interface Areas, Tanzania

Nhamitambo¹

2017

J Infect Dis Epidemiol

View full text Add to dashboard Cite

Trypanosomosis is a major neglected disease of animals and man that causes great negative socio-economic impact in many African countries. It is caused by protozoan parasites of the blood from the genus Trypanosoma. Previous studies have investigated the prevalence and risk factors of trypanosomosis in Tanzania, but none has been done in the human/ livestock/wildlife interface areas of Mikumi National Park. The present study determined prevalence of trypanosomosis in cattle blood sampled in five villages of the Mikumi interface areas. Trypanosome species were identified using the nested ITS-PCR and SRA-LAMP. Acquired biodata and spatial information were used for the analysis of risk factors based on the proximity from the park. Data analysis for categorical variables was performed using Chi-square, Fishers exact test, Odds and Risk ratios. Maps were created using the ArcMap ™ version 10.1 GIS software (ESRI 2012). Overall prevalence was 51.47%. Infection significantly varied among the 5 villages (p = 0.0022). The study identified 7 different species of trypanosomes. Trypanosoma simiae had the highest rate of infection 48.15%, followed by T. theileri 26.67%, T. vivax 16.30%, T. brucei brucei 4.44%, T. congolense forest 2.22%, T. simiae tsavo 1.48% and T. congolense kilifi 0.74%. No zoonotic species were identified. High density vegetation (p = 0.0001) and human activity (livestock market and cattle movement) (p = 0.0001) were identified as strong risk factors for infection. Areas with charco dams (p = 0.0001) and those close to tsetse screens and traps (p = 0.0006) had significantly lower infection prevalence. Identifying risk factors, quantifying the risk and doing spatial analysis is essential to determine the control measures to be used in the affected rural communities.

show abstract

Modeling the Control of Trypanosomiasis Using Trypanocides or Insecticide-Treated Livestock

Cited by 64 publications

References 45 publications

Improvements on Restricted Insecticide Application Protocol for Control of Human and Animal African Trypanosomiasis in Eastern Uganda

Improvements on Restricted Insecticide Application Protocol for Control of Human and Animal African Trypanosomiasis in Eastern Uganda

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

Molecular Identification of Trypanosome Species in Cattle of the Mikumi Human/Livestock/Wildlife Interface Areas, Tanzania

Contact Info

Product

Resources

About