Cystic Echinococcosis Control in South America: Integrating Mathematical Modelling and Health Economics for Informed Decision-Making
Creators: name: Widdicombe, Joanne
Publisher: name: University of Surrey
Year: 2025
Subjects: Cystic echinococcosis
Epidemiology
Health Economics
Mathematical Models

description: Cystic echinococcosis (CE) is a zoonotic neglected tropical disease (zNTD) which imposes
description: considerable financial burden to endemic countries. The World Health Organisation’s
description: 2021–2030 roadmap on NTDs aims to achieve intensified control in hyperendemic areas
description: across 17 countries by 2030. Effective disease control interventions and the successful
description: scale-up of such programmes depend on a thorough understanding of disease transmission
description: dynamics, as well as the associated costs and return on investment for these interventions.
description: The objective of this thesis is to enhance our epidemiological understanding of CE in South
description: America through the integration of mathematical modelling and economic evaluation
description: methods.
description: Chapter 2 presents a Scoping Review of the cost and cost-effectiveness of CE control
description: interventions targeting zoonotic hosts. The review highlights the scarcity of published
description: data on the cost of CE control measures, with much of the available data being incomplete
description: or aggregated. This chapter underscores the need for greater transparency by programme
description: managers and for more detailed cost information to be made available. This work was
description: published in PLoS Neglected Tropical Diseases (Widdicombe et al., 2022).
description: In Chapter 3, I evaluated a pilot surveillance and control programme for CE in Peru (2015
description: to 2019). This chapter provides a descriptive analysis of the data collected during the
description: pilot study and establishes base line prevalence values of canine CE in the different regions
description: included in the pilot. It also details the costs of the various control strategies and the
description: intervention preferences of the veterinarians implementing these measures. The results
description: indicated that control interventions were deliverable to remote locations, and that a
description: largescale CE control programme is feasible in Peru. However, the pilot study also highlighted
description: the challenges of implementing and coordinating a control programme in remote locations,
description: and the necessary infrastructure required for success.
description: In Chapter 4, I explored preferences for equity in health resource allocation by One Health
description: professionals. This research examined how decisions on distributing health gains within
description: a population reflect a trade-off between maximising efficiency (maximum health across a
description: population) and reducing disparities in health based on need (equity). Through a
description: questionnaire, the study aimed to elucidate inequity aversion among One Health professionals.
description: The results showed that respondents were willing to sacrifice a considerable fraction of
description: total health to achieve a more equal distribution. However, achieving equitable health
description: outcomes for vulnerable populations requires policymakers to commit to equitable decisions,
description: necessitating increased resource prioritisation and financial investment.
description: Chapter 5 introduces the CEST model, a stochastic disease transmission model for Cystic
description: Echinococcosis, designed to capture the lifecycle and disease dynamics of CE in both its
description: definitive (dogs) and intermediate (sheep) hosts. The model is calibrated with data from
description: Río Negro, Argentina, and accounts for seasonal fluctuations in livestock husbandry. It
description: includes a retrospective analysis of historical interventions employed in the Río Negro
description: control programme since its onset in 1980, as well as a prospective analysis modelling
description: different intervention scenarios for 2025-2035. Deworming with praziquantel, and sheep
description: vaccination with EG95 are simulated at different frequencies and coverage levels. CE
description: prevalence in both dogs and sheep, as well as the predicted change in risk to humans
description: with each intervention, are presented annually. The model demonstrates that current
description: interventions can reduce disease prevalence in dogs and sheep, however even when dog
description: deworming was modelled at increased frequencies and the coverage of sheep vaccination
description: was enhanced, sporadic transmission was predicted to continue.
description: Chapter 6 estimates the cost of implementing a new regional control programme for CE
description: in South America comparing the costs of three different control programmes with
description: different frequencies of dog deworming against the status quo of taking no action. Using the
description: CEST model to simulate transmission dynamics, the cost-effectiveness of each
description: intervention was assessed. All control programmes were cost-effective when considered in a cost
description: per case avoided analysis. However, the programme with the least frequent treatment,
description: every 6 months, was the most cost-effective. The majority of CE programme costs were
description: associated with delivery logistics including the costs of vehicles, fuel, and wages, rather
description: than drug costs. The financial burden in CE-affected areas was overwhelmingly due to
description: livestock losses (99%), with human healthcare costs contributing less than 1% of the total
description: burden. A limitation of this research is the lack of published economic data on CE control
description: interventions and the under-reporting of human CE cases, which complicates traditional
description: cost-effectiveness analysis.
description: Chapter 7 provides a general discussion on the control of Cystic Echinococcosis in South
description: America, addressing the limitations of current data and suggesting avenues for further
description: research. This chapter reflects on the findings from earlier chapters, emphasising the
description: challenges posed by incomplete economic data, under-reporting of human cases, and the
description: logistical complexities of implementing control programmes. It also highlights the
description: importance of more detailed and transparent reporting in future studies to improve the accuracy
description: of cost-effectiveness analyses. The chapter concludes by identifying key areas where
description: further research is needed, particularly the need to better understand the production losses
description: associated with CE and to address the under-reporting and lack of specificity in CE case
description: reporting in the region.