Are We on Our Way to Achieving the 2020 Goals for Schistosomiasis Morbidity Control Using Current World Health Organization Guidelines?

Toor, Jaspreet; Alsallaq, Ramzi; Truscott, James E.; Turner, Hugo C.; Werkman, Marleen; Gurarie, David; King, Charles H.; Anderson, Roy M.

doi:10.1093/cid/ciy001

Cited by 94 publications

(117 citation statements)

References 26 publications

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“…An alternative approach using deterministic compartment-based models, has been used to investigate the effects of vaccination, but this approach allows for less scope for including biological complexity [22, 23]. The transmission cycle, which is related to previously published models [11, 21, 24], is as follows:Mature adult schistosomes reproduce within human hosts monogamously. To account for within-host competition, fecundity (egg production per female schistosome) decays exponentially with the total number of mature schistosomes currently contained in the human host.…”

Section: Methodsmentioning

confidence: 99%

“…However, several recent studies in Africa have demonstrated limited progress in reducing prevalence in localized high-transmission areas, despite high MDA coverage [7–9]. Mathematical modelling suggests that high coverage of both children and adults over sustained periods of time is required for MDA to control schistosomiasis in high-transmission areas, which may prove to be beyond practical limits [10, 11]. …”

Section: Introductionmentioning

confidence: 99%

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Vaccination or mass drug administration against schistosomiasis: a hypothetical cost-effectiveness modelling comparison

et al. 2019

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BackgroundSchistosomiasis is a neglected tropical disease, targeted by the World Health Organization for reduction in morbidity by 2020. It is caused by parasitic flukes that spread through contamination of local water sources. Traditional control focuses on mass drug administration, which kills the majority of adult worms, targeted at school-aged children. However, these drugs do not confer long-term protection and there are concerns over the emergence of drug resistance. The development of a vaccine against schistosomiasis opens the potential for control methods that could generate long-lasting population-level immunity if they are cost-effective.MethodsUsing an individual-based transmission model, matched to epidemiological data, we compared the cost-effectiveness of a range of vaccination programmes against mass drug administration, across three transmission settings. Health benefit was measured by calculating the heavy-intensity infection years averted by each intervention, while vaccine costs were assessed against robust estimates for the costs of mass drug administration obtained from data. We also calculated a critical vaccination cost, a cost beyond which vaccination might not be economically favorable, by benchmarking the cost-effectiveness of potential vaccines against the cost-effectiveness of mass drug administration, and examined the effect of different vaccine protection durations.ResultsWe found that sufficiently low-priced vaccines can be more cost-effective than traditional drugs in high prevalence settings, and can lead to a greater reduction in morbidity over shorter time-scales. MDA or vaccination programmes that target the whole community generate the most health benefits, but are generally less cost-effective than those targeting children, due to lower prevalence of schistosomiasis in adults.ConclusionsThe ultimate cost-effectiveness of vaccination will be highly dependent on multiple vaccine characteristics, such as the efficacy, cost, safety and duration of protection, as well as the subset of population targeted for vaccination. However, our results indicate that if a vaccine could be developed with reasonable characteristics and for a sufficiently low cost, then vaccination programmes can be a highly cost-effective method of controlling schistosomiasis in high-transmission areas. The population-level immunity generated by vaccination will also inevitably improve the chances of interrupting transmission of the disease, which is the long-term epidemiological goal.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vaccination or mass drug administration against schistosomiasis: a hypothetical cost-effectiveness modelling comparison

et al. 2019

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“…For both of these infections, current guidelines suggest that treatments should be targeted at children, with different frequencies according to prevalence. The modeling studies in this special issue suggest that the current guidelines might be altered slightly to optimize their impact, through either targeting adults or changing the thresholds for switching strategies [40,41] (Table 2).…”

Section: Mass Drug Administrationmentioning

confidence: 99%

“…All of the articles on MDA policies highlight the importance of the epidemiological setting, the appropriate group being targeted, and systematic nonadherence, where particular groups either do not have access to or are refusing treatment, and note that these are often poorly measured ( Figure 3) [40,41,[43][44][45]. The issue of systematic nonadherence has been highlighted in modeling studies for many years but has recently become a point of focus again [11,46,47].…”

Section: Mass Drug Administrationmentioning

confidence: 99%

Counting Down the 2020 Goals for 9 Neglected Tropical Diseases: What Have We Learned From Quantitative Analysis and Transmission Modeling?

Hollingsworth

2018

Clinical Infectious Diseases

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The control of neglected tropical diseases (NTDs) has received huge investment in recent years, leading to large reductions in morbidity. In 2012, the World Health Organization set ambitious targets for eliminating many of these diseases as a public health problem by 2020, an aspiration that was supported by donations of treatments, intervention materials, and funding committed by a broad partnership of stakeholders in the London Declaration on NTDs. Alongside these efforts, there has been an increasing role for quantitative analysis and modeling to support the achievement of these goals through evaluation of the likely impact of interventions, the factors that could undermine these achievements, and the role of new diagnostics and treatments in reducing transmission. In this special issue, we aim to summarize those insights in an accessible way. This article acts as an introduction to the special issue, outlining key concepts in NTDs and insights from modeling as we approach 2020.

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“…As standard methods for diagnosing schistosomiasis are quite insensitive, experts believe that actual estimates of the number of people currently infected with schistosomiasis ranges between 400 and 600 million based on the hypothesis that there is a one to one (1:1) ratio between egg-positive infected individual and an egg-negative infected individual [3]. Schistosomiasis is estimated to cause 280,000 deaths annually in 78 countries and about 3.8 million disability adjusted life years credited to the disease [4,5].…”

Section: Introductionmentioning

confidence: 99%

Schistosomiasis vaccine development: update on human clinical trials

Molehin

2020

J Biomed Sci

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Schistosomiasis causes significant levels of morbidity and mortality in many geographical regions of the world. The disease is caused by infections with parasitic blood flukes known as schistosomes. The control of schistosomiasis over the last several decades has been centered on the mass drug administration (MDA) of praziquantel (PZQ), which is the only drug currently available for treatment. Despite the concerted efforts of MDA programs, the prevalence and transmission of schistosomiasis has remained largely unchecked due to the fact that PZQ is ineffective against juvenile schistosomes, does not prevent re-infection and the emergence of PZQ-resistant parasites. In addition, other measures such as the water, sanitation and hygiene programs and snail intermediate hosts control have had little to no impact. These drawbacks indicate that the current control strategies are severely inadequate at interrupting transmission and therefore, implementation of other control strategies are required. Ideally, an efficient vaccine is what is needed for long term protection thereby eliminating the current efforts of repeated mass drug administration. However, the general consensus in the field is that the integration of a viable vaccine with MDA and other control measures offer the best chance of achieving the goal of schistosomiasis elimination. This review focuses on the present status of schistosomiasis vaccine candidates in different phases of human clinical trials and provide some insight into future vaccine discovery and design.

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Are We on Our Way to Achieving the 2020 Goals for Schistosomiasis Morbidity Control Using Current World Health Organization Guidelines?

Cited by 94 publications

References 26 publications

Vaccination or mass drug administration against schistosomiasis: a hypothetical cost-effectiveness modelling comparison

Vaccination or mass drug administration against schistosomiasis: a hypothetical cost-effectiveness modelling comparison

Counting Down the 2020 Goals for 9 Neglected Tropical Diseases: What Have We Learned From Quantitative Analysis and Transmission Modeling?

Schistosomiasis vaccine development: update on human clinical trials

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