Control of Ascaris infection by chemotherapy: which is the most cost-effective option?

Guyatt, Helen; Chan, M. S.; Medley, Graham F.; Bundy, Donald

doi:10.1016/0035-9203(95)90638-x

Cited by 33 publications

(14 citation statements)

References 15 publications

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“…Rather, mathematical models of school-age targeted treatments are in broad consensus with the view that this strategy is a cost-effective means of controlling morbidity. 206,212 This is in accordance with empirical evidence demonstrating that de-worming children produces improvements in growth, educational attainment 214e216 and school participation 217 (although it is noteworthy that quantifying the benefit of de-worming is notoriously difficult and is the subject of some recent controversy). 218 Moreover, the schools' infrastructure offers a convenient conduit to achieve high coverage of the most heavily infected individuals.…”

Section: Modeling Treatmentsupporting

confidence: 86%

“…the level of infection in the absence of intervention), 206 and (4) by linking rounds of treatments to monetary costs, cost-effectiveness analysis. 212 Although the effect of mass treatments has largely been assessed in terms of population-level effects, such as bounce-back (reinfection) times following treatment 56 or the effectiveness of targeting specific age groups, 206 models have also been used to explore individual-based treatment effects. In particular, the so-called selective strategy, which involves selectively treating heavily infected or high risk individuals, has been shown to be extremely effective in reducing average worm burdens, so long as the degree of overdispersion is high.…”

Section: Modeling Treatmentmentioning

confidence: 99%

See 1 more Smart Citation

Ascaris lumbricoides

Walker

Hall

Basáñez

2013

Ascaris: The Neglected Parasite

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Section: Modeling Treatmentsupporting

confidence: 86%

Section: Modeling Treatmentmentioning

confidence: 99%

Ascaris lumbricoides

Walker

Hall

Basáñez

2013

Ascaris: The Neglected Parasite

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“…Cost-effectiveness analysis using parameterised dynamic infection models enables the long-term effectiveness of an intervention to be estimated [96]–[98], avoiding the limitation of so-called static economic models [97], which consider only the effectiveness of an intervention at a particular point in time (e.g., [99], [100]) or over a limited period of follow-up (e.g., [101], [102]). This permits a more comprehensive assessment of effectiveness and allows interventions that elicit different dynamics to be compared fairly.…”

Section: Research Gaps In Helminth Modellingmentioning

confidence: 99%

“…A fair comparison of the effectiveness of these drugs must account for the markedly different durations over which they act. Linking infection models to the prevalence of disease and associated morbidities [29], [30] further improves the capacity to capture the full benefits of an intervention [97], [98], and the predictive capability of models permits a priori comparison of a range of intervention strategies under various scenarios [96], [98]. Cost-effectiveness analysis using dynamic infection models needs to be further developed and made more accessible as a decision-making tool for the planners and implementers of control initiatives.…”

Section: Research Gaps In Helminth Modellingmentioning

confidence: 99%

A Research Agenda for Helminth Diseases of Humans: Modelling for Control and Elimination

et al. 2012

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Mathematical modelling of helminth infections has the potential to inform policy and guide research for the control and elimination of human helminthiases. However, this potential, unlike in other parasitic and infectious diseases, has yet to be realised. To place contemporary efforts in a historical context, a summary of the development of mathematical models for helminthiases is presented. These efforts are discussed according to the role that models can play in furthering our understanding of parasite population biology and transmission dynamics, and the effect on such dynamics of control interventions, as well as in enabling estimation of directly unobservable parameters, exploration of transmission breakpoints, and investigation of evolutionary outcomes of control. The Disease Reference Group on Helminth Infections (DRG4), established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR), was given the mandate to review helminthiases research and identify research priorities and gaps. A research and development agenda for helminthiasis modelling is proposed based on identified gaps that need to be addressed for models to become useful decision tools that can support research and control operations effectively. This agenda includes the use of models to estimate the impact of large-scale interventions on infection incidence; the design of sampling protocols for the monitoring and evaluation of integrated control programmes; the modelling of co-infections; the investigation of the dynamical relationship between infection and morbidity indicators; the improvement of analytical methods for the quantification of anthelmintic efficacy and resistance; the determination of programme endpoints; the linking of dynamical helminth models with helminth geostatistical mapping; and the investigation of the impact of climate change on human helminthiases. It is concluded that modelling should be embedded in helminth research, and in the planning, evaluation, and surveillance of interventions from the outset. Modellers should be essential members of interdisciplinary teams, propitiating a continuous dialogue with end users and stakeholders to reflect public health needs in the terrain, discuss the scope and limitations of models, and update biological assumptions and model outputs regularly. It is highlighted that to reach these goals, a collaborative framework must be developed for the collation, annotation, and sharing of databases from large-scale anthelmintic control programmes, and that helminth modellers should join efforts to tackle key questions in helminth epidemiology and control through the sharing of such databases, and by using diverse, yet complementary, modelling approaches.

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“…Because the proportion of moderate to heavy infections increases non-linearly with an increasing prevalence (Figure 1), higher thresholds of 60% and 80% provide a simple but epidemiologically sound and cost-effective basis on which to treat twice or three times a year, at least in the first 1–2 years of a programme. While models of reinfection indicate that it may be more important to achieve higher population coverage than more frequent treatment, [33] it is easier and less costly to achieve high coverage of children than adults. Giving treatments three times a year in places with a high initial prevalence will bring down mean worm burdens more quickly than treating only twice a year, while missing one of three treatments will achieve better annual coverage of any given individual than if one of only two treatments is missed, as the WHO recommend when the initial prevalence is greater than 50%.…”

Section: Discussionmentioning

confidence: 99%

The Costs and Cost-Effectiveness of Mass Treatment for Intestinal Nematode Worm Infections Using Different Treatment Thresholds

2009

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BackgroundIt is estimated that almost a half of all of people living in developing countries today are infected with roundworms, hookworms, or whipworms or combinations of these types of intestinal nematode worms. They can all be treated using safe, effective, and inexpensive single-dose generic drugs costing as little as USD 0.03 per person treated when bought in bulk. The disease caused by intestinal nematodes is strongly related to the number of worms in the gut, and it is typical to find that worms tend to be aggregated or clumped in their distribution so that <20% of people may harbour >80% of all worms. This clumping of worms is greatest when the prevalence is low. When the prevalence rises above 50%, the mean worm burden increases exponentially, worms are less clumped, and more people are likely to have moderate to heavy infections and may be diseased. Children are most at risk. For these reasons, the World Health Organization (WHO) currently recommends mass treatment of children ≥1 year old without prior diagnosis when the prevalence is ≥20% and treatment twice a year when the prevalence is ≥50%.Methods and FindingsThe risk of moderate to heavy infections with intestinal nematodes was estimated by applying the negative binomial probability distribution, then the drug cost of treating diseased individuals was calculated based on different threshold numbers of worms. Based on this cost analysis, a new three-tier treatment regime is proposed: if the combined prevalence is >40%, treat all children once a year; >60% treat twice a year; and >80% treat three times a year. Using average data on drug and delivery costs of USD 0.15 to treat a school-age child and USD 0.25 to treat a pre-school child (with provisos) the cost of treating children aged 2–14 years was calculated for 105 low- and low-middle-income countries and for constituent regions of India and China based on estimates of the combined prevalence of intestinal nematode worms therein. The annual cost of the three-tier threshold was estimated to be USD 224 million compared with USD 276 million when the current WHO recommendations for mass treatment were applied.ConclusionThe three-tier treatment thresholds were less expensive and more effective as they allocated a greater proportion of expenditures to treating infected individuals when compared with the WHO thresholds (73% compared with 61%) and treated a larger proportion of individuals with moderate to heavy worm burdens, arbitrarily defined as more than 10 worms per person (31% compared with 21%).

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Control of Ascaris infection by chemotherapy: which is the most cost-effective option?

Cited by 33 publications

References 15 publications

Ascaris lumbricoides

Ascaris lumbricoides

A Research Agenda for Helminth Diseases of Humans: Modelling for Control and Elimination

The Costs and Cost-Effectiveness of Mass Treatment for Intestinal Nematode Worm Infections Using Different Treatment Thresholds

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