Assessing Strategies Against Gambiense Sleeping Sickness Through Mathematical Modeling

Rock, Kat S.; Ndeffo-Mbah, Martial L.; Castaño, María Soledad; Palmer, Cody; Pandey, Abhishek; Atkins, Katherine E.; Ndung’u, Joseph Mathu; Hollingsworth, T. Déirdre; Galvani, Alison P.; Bever, Caitlin A.; Chitnis, Nakul; Keeling, Matthew James

doi:10.1093/cid/ciy018

Cited by 38 publications

(40 citation statements)

References 28 publications

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“…Added to this would be the disability-life years (DALYs) averted due to a reduction in human suffering and mortality from a disease which is fatal in untreated individuals. Ongoing HAT modelling work [32] can also incorporate these new cost data from Chad. Meanwhile the authors conclude that "all models agreed that vector control would consistently avert most infections and likely lead to elimination by 2030 in all considered scenarios" [32].…”

Section: Discussionmentioning

confidence: 99%

Delivering ‘tiny targets’ in a remote region of southern Chad: a cost analysis of tsetse control in the Mandoul sleeping sickness focus

et al. 2020

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Background: Since 2012, the World Health Organisation and the countries affected by the Gambian form of human African trypanosomiasis (HAT) have been committed to eliminating the disease, primarily through active case-finding and treatment. To interrupt transmission of Trypanosoma brucei gambiense and move more rapidly towards elimination, it was decided to add vector control using 'tiny targets'. Chad's Mandoul HAT focus extends over 840 km 2 , with a human population of 39,000 as well as 14,000 cattle and 3000 pigs. Some 2700 tiny targets were deployed annually from 2014 onwards. Methods: A protocol was developed for the routine collection of tsetse control costs during all field missions. This was implemented throughout 2015 and 2016, and combined with the recorded costs of the preliminary survey and sensitisation activities. The objective was to calculate the full costs at local prices in Chad. Costs were adjusted to remove research components and to ensure that items outside the project budget lines were included, such as administrative overheads and a share of staff salaries. Results: Targets were deployed at about 60 per linear km of riverine tsetse habitat. The average annual cost of the operation was USD 56,113, working out at USD 66.8 per km 2 protected and USD 1.4 per person protected. Of this, 12.8% was an annual share of the initial tsetse survey, 40.6% for regular tsetse monitoring undertaken three times a year, 36.8% for target deployment and checking and 9.8% for sensitisation of local populations. Targets accounted for 8.3% of the cost, and the cost of delivering a target was USD 19.0 per target deployed. Conclusions: This study has confirmed that tiny targets provide a consistently low cost option for controlling tsetse in gambiense HAT foci. Although the study area is remote with a tsetse habitat characterised by wide river marshes, the costs were similar to those of tiny target work in Uganda, with some differences, in particular a higher cost per target delivered. As was the case in Uganda, the cost was between a quarter and a third that of historical target operations using full size targets or traps.

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Section: Discussionmentioning

confidence: 99%

Delivering ‘tiny targets’ in a remote region of southern Chad: a cost analysis of tsetse control in the Mandoul sleeping sickness focus

et al. 2020

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“…Exactly those conditions are found for other diseases now on the cusp of global eradication (e.g. polio [4], Dracunculiasis [5] and human Africa trypanosomiasis [6]). It follows that effective disease elimination might be guided by techniques for differentiating between efforts that will lead to stable disease elimination and scenarios where cases are diminished without a corresponding shift in the system's stability.…”

Section: Introductionmentioning

confidence: 95%

Early warning signals of malaria resurgence in Kericho, Kenya

2020

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Campaigns to eliminate infectious diseases could be greatly aided by methods for providing early warning signals of resurgence. Theory predicts that as a disease transmission system undergoes a transition from stability at the disease-free equilibrium to sustained transmission, it will exhibit characteristic behaviours known as critical slowing down, referring to the speed at which fluctuations in the number of cases are dampened, for instance the extinction of a local transmission chain after infection from an imported case. These phenomena include increases in several summary statistics, including lag-1 autocorrelation, variance and the first difference of variance. Here, we report the first empirical test of this prediction during the resurgence of malaria in Kericho, Kenya. For 10 summary statistics, we measured the approach to criticality in a rolling window to quantify the size of effect and directions. Nine of the statistics increased as predicted and variance, the first difference of variance, autocovariance, lag-1 autocorrelation and decay time returned early warning signals of critical slowing down based on permutation tests. These results show that time series of disease incidence collected through ordinary surveillance activities may exhibit characteristic signatures prior to an outbreak, a phenomenon that may be quite general among infectious disease systems.

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“…The model was fitted to case data from the health zones and projections were simulated for 2020-2050 [14,15]. The same underlying model framework has also been used to examine the epidemiology of gHAT in DRC and Chad [6,[16][17][18][19].…”

Section: Settings and Strategiesmentioning

confidence: 99%

Cost-effectiveness of sleeping sickness elimination campaigns in five settings of the Democratic Republic of Congo

Antillón

Huang

Crump

et al. 2020

Preprint

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Background: Gambiense human African trypanosomiasis (gHAT) is marked for elimination of transmission (EOT) by 2030, but the disease persists in several low-income countries. We examine the cost-effectiveness of four gHAT elimination strategies in Democratic Republic of Congo (DRC), which has the highest burden of gHAT. Methods: We compared four strategies against gHAT by coupling a transmission model with a health outcomes model in five settings -- spanning low- to high-risk. Alongside passive surveillance (PS) in fixed health facilities, the strategies included active screening (AS) at average or high coverage levels, both alone or with vector control (VC). A scale-back algorithm was devised to simulate cessation of AS and VC when no cases were reported for three consecutive years. Outcomes were denominated in disability-adjusted life-years (DALYs) and costs until 2040 were denominated in 2018 US$. Results: In high or moderate-risk settings, costs of gHAT strategies are primarily driven by AS and, if used, VC. Due to the cessation of AS and VC most investments (75-80%) will be made by 2030 and VC might be cost-saving while ensuring EOT. In low-risk settings, costs are driven by PS, and minimum-cost strategies consisting of AS and PS lead to EOT by 2030 with high probability. Conclusion: In many settings, the case for EOT by 2030 is a sensible use of resources, and investments in gHAT will decelerate within this decade in moderate- and low-risk regions.

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Assessing Strategies Against Gambiense Sleeping Sickness Through Mathematical Modeling

Cited by 38 publications

References 28 publications

Delivering ‘tiny targets’ in a remote region of southern Chad: a cost analysis of tsetse control in the Mandoul sleeping sickness focus

Delivering ‘tiny targets’ in a remote region of southern Chad: a cost analysis of tsetse control in the Mandoul sleeping sickness focus

Early warning signals of malaria resurgence in Kericho, Kenya

Cost-effectiveness of sleeping sickness elimination campaigns in five settings of the Democratic Republic of Congo

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