Identifying regions for enhanced control of gambiense sleeping sickness in the Democratic Republic of Congo

Huang, Ching‐I; Crump, R. E.; Brown, Paul E.; Spencer, Simon E. F.; Miaka, Erick Mwamba; Shampa, Chansy; Keeling, Matthew James; Rock, Kat S.

doi:10.1038/s41467-022-29192-w

Cited by 13 publications

(27 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results of the model fitting for the models with and without animal transmission, in the form of 1 000 realisations from the joint posterior distribution of all fitted parameters, were used to make projections under two main strategies. These are a subset of those reported in the paper on projections for the model without animal transmission [ 30 ]. In both strategies, AS was continued beyond 2016 at the mean level observed in that health zone in the period 2012 to 2016, this was chosen as reflecting an achievable level of AS in that locale with recent, if not current, resource availability.…”

Section: Methodsmentioning

confidence: 99%

Modelling to infer the role of animals in gambiense human African trypanosomiasis transmission and elimination in the DRC

et al. 2022

Self Cite

View full text Add to dashboard Cite

Gambiense human African trypanosomiasis (gHAT) has been targeted for elimination of transmission (EoT) to humans by 2030. Whilst this ambitious goal is rapidly approaching, there remain fundamental questions about the presence of non-human animal transmission cycles and their potential role in slowing progress towards, or even preventing, EoT. In this study we focus on the country with the most gHAT disease burden, the Democratic Republic of Congo (DRC), and use mathematical modelling to assess whether animals may contribute to transmission in specific regions, and if so, how their presence could impact the likelihood and timing of EoT. By fitting two model variants—one with, and one without animal transmission—to the human case data from 2000–2016 we estimate model parameters for 158 endemic health zones of the DRC. We evaluate the statistical support for each model variant in each health zone and infer the contribution of animals to overall transmission and how this could impact predicted time to EoT. We conclude that there are 24/158 health zones where there is substantial to decisive statistical support for some animal transmission. However—even in these regions—we estimate that animals would be extremely unlikely to maintain transmission on their own. Animal transmission could hamper progress towards EoT in some settings, with projections under continuing interventions indicating that the number of health zones expected to achieve EoT by 2030 reduces from 68/158 to 61/158 if animal transmission is included in the model. With supplementary vector control (at a modest 60% tsetse reduction) added to medical screening and treatment interventions, the predicted number of health zones meeting the goal increases to 147/158 for the model including animal transmission. This is due to the impact of vector reduction on transmission to and from all hosts.

show abstract

Section: Methodsmentioning

confidence: 99%

Modelling to infer the role of animals in gambiense human African trypanosomiasis transmission and elimination in the DRC

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…The year of elimination of transmission (EoT) is defined in our deterministic model as the first year in which less than one case is found, in line with the proxy threshold used to determine EoT in other gHAT modelling [35]. Whilst it is imperfect, this level of new infections has been found to be an adequate approximation of the threshold to simulate local extinction as characterized in comparisons with stochastic models [36].…”

Section: Methodsmentioning

confidence: 99%

Health economic evaluation of strategies to eliminategambiensehuman African trypanosomiasis in the Mandoul disease focus of Chad

Antillón

Huang

Sutherland

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

Human African trypanosomiasis, caused by the gambiense subspecies of Trypanosoma brucei (gHAT), is a deadly parasitic disease transmitted by tsetse. Partners from around the world have stepped up efforts to eliminate the disease, and the Chadian government have had a particular focus on the previously high-prevalence setting of Mandoul. In this study, we evaluate the economic efficiency of the intensified strategies that were put in place from 2014 aimed at interrupting transmission of gHAT, and we make recommendations on the best way forward based on both epidemiological projections and cost-effectiveness. In our analysis we use a dynamic transmission model fit to epidemiological data from Mandoul to evaluate the cost-effectiveness of combinations of active screening, improved passive screening (defined as an expansion of the number of health posts capable of screening for gHAT), and vector control activities (the deployment of Tiny Targets). For cost-effectiveness analyses, our primary outcome is disease burden, denominated in disability-adjusted life-years (DALYs), and costs, denominated in 2020 US$. Although active and passive screening have enabled more rapid diagnosis and accessible treatment in Mandoul, the addition of vector control provided good value-for-money (at less than $750/DALY averted) and substantially increased the probability of reaching the 2030 elimination target for gHAT as set by the World Health Organization. Our transmission modelling and economic evaluations suggests that the gains have been made could be maintained by robust passive screening, and the inclusion of active screening and vector control strategies could be considered for other foci in the country with active transmission. Our analysis speaks to comparative efficiency, and it does not take into account all possible considerations; for instance, any cessation of on-going active screening should first consider that strong surveillance activities will be critical to verify elimination of transmission and to protect against the possible importation of infection from neighbouring endemic foci.

show abstract

“…Previous studies have shown that the effectiveness of VC (measured by the annual reduction in tsetse population density) is between 80 and 99% [13, 21–23]. Based on reported VC effectiveness, modelling exercises predict a rapid decline in underlying new infections when VC is used to supplement medical interventions and that EoT is expected to be achieved within four years of starting VC roll out [24].…”

Section: Methodsmentioning

confidence: 99%

“…Based on reported VC effectiveness, modelling exercises predict a rapid decline in underlying new infections when VC is used to supplement medical interventions and that EoT is expected to be achieved within four years of starting VC roll out [24].…”

Section: Current Interventionsmentioning

confidence: 99%

See 1 more Smart Citation

A modelling assessment of short- and medium-term risks of programme interruptions for gambiense human African trypanosomiasis in the DRC

Huang

Crump

Crowley

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

Gambiense human African trypanosomiasis (gHAT) is a deadly vector-borne, neglected tropical disease found in West and Central Africa targeted for elimination of transmission (EoT) by 2030. The recent pandemic has illustrated how it can be important to quantify the impact that unplanned disruption to programme activities may have in achieving elimination of transmission. We used a previously developed model of gHAT fitted to data from the Democratic Republic of Congo, a country with the highest global case burden, to explore how interruptions to intervention activities, due to e.g. COVID-19, Ebola or political instability, could impact progress towards EoT and gHAT burden. We simulated transmission and reporting dynamics in 38 health zones under six interruption scenarios lasting for nine or twenty-one months. Included in the interruption scenarios are the cessation of active screening in all scenarios and a reduction in passive detection rates and a delay or suspension of vector control deployments in some scenarios. Our results indicate that, even under the most extreme 21-month interruption scenario, EoT is not predicted to be delayed by more than one additional year compared to the length of the interruption. If existing vector control deployments continue, we predict no delay in achieving EoT even when both active and passive screening activities are interrupted. If passive screening remains fully functional, we expect a marginal negative impact on transmission, however this depends on the strength of passive screening in each health zone. We predict a pronounced increase in additional gHAT disease burden (morbidity and mortality) in many health zones if both active and passive screening were interrupted compared to the interruption of active screening alone. The ability to continue existing vector control during medical activity interruption is also predicted to avert a moderate proportion of disease burden.Author SummaryWhilst the COVID-19 pandemic has produced wide-spread disruption for many disease programmes there are also a range of other factors that continue to risk programme interruptions including other disease outbreaks (e.g. Ebola, cholera, yellow fever, and measles) and the potential for political instability. In this study we examine the impact of interruptions by external factors to the gambiense human African trypanosomiasis (gHAT, sleeping sickness) elimination programme of the Democratic Republic of the Congo, a country which has the highest global case burden. We use our previously fitted gHAT model to simulate how transmission dynamics might be impacted by disruption to medical interventions and (where relevant) vector control activities in 38 health zones of the former Bandundu province. For each of the six interruption scenarios we use the model to forecast case numbers and disease burden as well as estimating the expected years and probabilities of elimination of transmission. This analysis provides invaluable insight into the impact that interruptions of any persuasion could have on burden, case reporting and time to achieve elimination of transmission of gHAT in the Democratic Republic of the Congo.

show abstract

Identifying regions for enhanced control of gambiense sleeping sickness in the Democratic Republic of Congo

Cited by 13 publications

References 40 publications

Modelling to infer the role of animals in gambiense human African trypanosomiasis transmission and elimination in the DRC

Modelling to infer the role of animals in gambiense human African trypanosomiasis transmission and elimination in the DRC

Health economic evaluation of strategies to eliminategambiensehuman African trypanosomiasis in the Mandoul disease focus of Chad

A modelling assessment of short- and medium-term risks of programme interruptions for gambiense human African trypanosomiasis in the DRC

Contact Info

Product

Resources

About