Matching the gHAT model to real case data
State-of-the art statistical fitting methodology has been used to automate calibration of a model of gambiense Human African Trypanosomiasis (gHAT) to longitudinal data (2000–2016) across endemic health zones of the Democratic Republic of Congo (DRC). Through modelling with this data we aim to quantify key underlying factors which contribute to the observational and transmission variation across the country.
The image opposite shows how well the model fits to the timeseries of reported cases, and where there has been a change in the passive case detection rate during the data collection period.
Data and analysis tool: Retrospective (2000-2016) DRC gHAT case data by health zone is available to view online via a data and analysis tool (GUI), providing online access to the vast amount of data and results of this research project in a user-friendly way.
Peer-reviewed paper: Crump, RE, Huang, C, Knock, E, Spencer, SEF, Brown, P, Miaka, EM, Chancy, S, Keeling, MJ, Rock, KS (2021). Quantifying epidemiological drivers of gambiense human African Trypanosomiasis across the Democratic Republic of Congo. PLoS Comp Biol. Paper summaries: English, French
Mathematical modelling has been used to study the overall impacts of combinations of the currently available intervention methods on transmission across the DRC and highlight regions requiring intensified interventions to achieve elimination of transmission (EOT) by the WHO’s 2030 goal. The Warwick gHAT model - previously developed and fitted to longitudinal human case data in DRC (see above) – was used to predict the expected numbers of active cases, passive cases and new infections.
Data and analysis tool: Projected case detections, new infections and estimated year of elimination of transmission of gHAT for DRC health zones, resulting from different intervention strategies, are available to view online via a data and analysis tool (GUI), providing online access to the vast amount of data and results of this research project in a user-friendly way.
Forthcoming paper: Huang, C, Crump, RE, Brown, P, Spencer SEF, Miaka, EM, Shampa, C, Keeling, MJ, Rock, KS (2020). Shrinking the gHAT map: identifying target regions for enhanced control in DRC [pre-print, not peer reviewed]. Paper summaries: English, French
Cost and cost-effectiveness evaluations
The Warwick gHAT model has been further expanded to provide the cost and cost-effectiveness of the four intervention strategies (see opposite) in terms of net benefit (cost of interventions vs cost of ill-health/disability/death), which is added to the model. Costs include diagnosis, confirmation, and staging via lumbar puncture, well as the cost of the drug itself and the administration. The research offers a number of different options highlighting the most efficient intervention strategy to achieve elimination by 2030 and the optimal strategy to lower costs.
Data and analysis tool: Projected costs of different intervention strategies and cost-effectiveness for 5 health zones in DRC are available to view online via a data and analysis tool (GUI), providing online access to the vast amount of data and results of this research project in a user-friendly way.
Forthcoming paper: Antillon, M, Huang, C, Crump, RE, Brown, P, Snijders, R, Miaka, EM, Rock, KS, Tediosi, F (2020). Economic evaluation of gHAT elimination campaigns in five distinct transmission settings in DRC pre-print, not peer reviewed]. Paper summaries: English, French
With limited numbers of active screening teams and resources, it is important to optimise their activities with the aim of driving towards elimination. With gHAT case numbers decreasing, we investigate how to optimise active screening visits to individual villages in DRC, such that the costs of the screening programmes can be minimised, while continuing to avert disability-adjusted life years. A stochastic gHAT infection model has been implemented across a range of active screening strategies and the net monetary benefit (NMB - cost of interventions vs cost of ill-health/disability/death) of each calculated.
Peer-reviewed paper: Davis, C, Rock, KS, Antillón, M, Miaka, EM, Keeling, MJ (2021). Cost-eﬀectiveness modelling to optimise active screening strategy for gambiense human African trypanosomiasis in endemic areas of the Democratic Republic of Congo. BMC Medicine. Paper summaries: English, French
COVID-19 interruption impact of gHAT
The Warwick and Swiss TPH teams independantly fitted their models to data to two health zones of the Democratic Republic of Congo (DRC) - Bagata and Mosango, both moderate-risk - and use them to assess what the impact of interruptions of medical interventions (active screening and passive surveillance) could have in these regions.
We predicted that delays in achieving elimination of transmission (EOT) would be similar to or less than the length of interruption. For Mosango, EOT may still be achieved by 2030, however, in Bagata the elimination goal is unlikely without intensifying interventions, even without interruptions.
The results suggest that retaining functioning passive surveillance, even partially, can help to avoid significant delays in EOT and to prevent substantial increases in mortality. Mitigation through increasing coverage of active screening following interruption could also improve the probability of meeting the 2030 EOT goal.
Peer-reviewed paper: Aliee, M, Castaño, MS, Davis, CN, Patel, S, Miaka, EM, Spencer, SEF, Keeling, MJ, Chitnis, N, Rock, KS (2021). Predicting the impact of COVID-19 interruptions on transmission of gambiense human African trypanosomiasis in two health zones of the Democratic Republic of Congo. Transactions of the Royal Society of Tropical Medicine and Hygiene. Paper summaries: Coming soon!
Meeting Report: NTD Modelling Consortium. The potential impact of programmes interruptions due to COVID-19 on 7 neglected tropical diseases: a modelling-based analysis