Modelling the Effects of Mass Drug Administration on the Molecular Epidemiology of Schistosomes

Lamberton, Poppy H. L.; Crellen, Thomas; Cotton, James A.; Webster, Joanne P.

doi:10.1016/bs.apar.2014.12.006

Cited by 11 publications

(13 citation statements)

References 147 publications

(160 reference statements)

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“…The current reservoir of untreated worms in adults may be diluting any resistant gene pool in children and therefore expanding treatment could increase the risk of drug resistance. This issue needs careful monitoring with more research to define markers to track via molecular epidemiological studies [73]. …”

Section: Discussionmentioning

confidence: 99%

Evaluating the variation in the projected benefit of community-wide mass treatment for schistosomiasis: Implications for future economic evaluations

et al. 2017

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BackgroundThe majority of schistosomiasis control programmes focus on targeting school-aged children. Expanding the use of community-wide mass treatment to reach more adults is under consideration. However, it should be noted that this would require a further increase in programmatic resources, international aid, and commitment for the provision of praziquantel. Consequently, it is important to understand (i) where a change of strategy would have the greatest benefit, and (ii) how generalisable the conclusions of field trials and analytical studies based on mathematical models investigating the impact of community-wide mass treatment, are to a broad range of settings.MethodsIn this paper, we employ a previously described deterministic fully age-structured schistosomiasis transmission model and evaluate the benefit of community-wide mass treatment both in terms of controlling morbidity and eliminating transmission for Schistosoma mansoni, across a wide range of epidemiological settings and programmatic scenarios. This included variation in the baseline relative worm pre-control burden in adults, the overall level of transmission in defined settings, choice of effectiveness metric (basing morbidity calculations on prevalence or intensity), the level of school enrolment and treatment compliance.ResultsCommunity-wide mass treatment was found to be more effective for controlling the transmission of schistosome parasites than using a school-based programme only targeting school-aged children. However, in the context of morbidity control, the potential benefit of switching to community-wide mass treatment was highly variable across the different scenarios analysed. In contrast, for areas where the goal is to eliminate transmission, the projected benefit of community-wide mass treatment was more consistent.ConclusionWhether community-wide mass treatment is appropriate will depend on the local epidemiological setting (i.e. the relative pre-control burden in adults and transmission intensity), and whether the goal is morbidity control or eliminating transmission. This has important implications regarding the generalisability of cost-effectiveness analyses of schistosomiasis interventions. Our results indicate that areas with poor school-enrolment/coverage could benefit more from community-wide treatment of praziquantel and should potentially be prioritised for any change in strategy. This work highlights the importance of not over-generalising conclusions and policy in this area, but of basing decisions on high quality epidemiological data and quantitative analyses of the impact of interventions in a range of settings.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2141-5) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Evaluating the variation in the projected benefit of community-wide mass treatment for schistosomiasis: Implications for future economic evaluations

et al. 2017

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“…Biological and epidemiological features of the disease, modes of transmission and host susceptibility can all influence an infectious agent's ability to switch host species [64,65]. Pathogens, particularly those with high mutation rates, antigenic diversity and short generation times, may rapidly adapt to new host species [66–68] and evidence suggests that RNA viruses are the most likely group of infectious agents to switch hosts and establish in humans [1].…”

Section: Multiple Hosts Pathogens and Modes Of Transmissionmentioning

confidence: 99%

“…Meanwhile, population genetics studies of schistosomiasis have been used to estimate levels of parasite genetic differentiation across host species in China and the Philippines, to give at least qualitative insights into the degree of transmission structuring between hosts [9,129]. Novel phylogenetic tools are increasingly being used to assessing rates and directionality of interspecies transmission, for example, of bovine tuberculosis [97] and rabies [98], while advances in phylodynamic approaches, in which transmission models are directly fitted to observed pathogen phylogenies, also show much promise [65,130]. …”

Section: Disentangling and Quantifying Transmissionmentioning

confidence: 99%

Who acquires infection from whom and how? Disentangling multi-host and multi-mode transmission dynamics in the ‘elimination’ era

Webster

Borlase

Rudge

2017

Phil. Trans. R. Soc. B

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Multi-host infectious agents challenge our abilities to understand, predict and manage disease dynamics. Within this, many infectious agents are also able to use, simultaneously or sequentially, multiple modes of transmission. Furthermore, the relative importance of different host species and modes can itself be dynamic, with potential for switches and shifts in host range and/or transmission mode in response to changing selective pressures, such as those imposed by disease control interventions. The epidemiology of such multi-host, multi-mode infectious agents thereby can involve a multi-faceted community of definitive and intermediate/secondary hosts or vectors, often together with infectious stages in the environment, all of which may represent potential targets, as well as specific challenges, particularly where disease elimination is proposed. Here, we explore, focusing on examples from both human and animal pathogen systems, why and how we should aim to disentangle and quantify the relative importance of multi-host multi-mode infectious agent transmission dynamics under contrasting conditions, and ultimately, how this can be used to help achieve efficient and effective disease control.This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.

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“…Vaccine design [ 11 ] and re-design of diagnostics [ 12 ] have also benefitted from the integration of genomics tools. At the parasite population level, we now understand that the population structures of the pathogens that cause visceral leishmaniasis and schistosomiasis are linked to resistance to pentavalent antimonial drugs [ 13 ] and to praziquantel [ 14 ].…”

Section: Genomics Research Has Revolutionized Our Understanding Of Inmentioning

confidence: 99%

“…Research on specific insecticide and anti-parasitic target genes of agents used in control programs highlights the importance of this approach [ 50 , 51 ]. Nevertheless, a review on MDA for schistosomiasis shows how genomics and genetics can be used to provide an understanding of population structure, transmission, potential spread of drug resistance and models that can be used to evaluate the effect of MDA and to determine cut-off points; this is an excellent example of the integration of genomics into disease control [ 14 ].…”

Section: The Continued Use Of Mass Drug Administration Is Controversimentioning

confidence: 99%

Neglected tropical diseases in the genomics era: re-evaluating the impact of new drugs and mass drug administration

Croft

2016

Genome Biol

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Modelling the Effects of Mass Drug Administration on the Molecular Epidemiology of Schistosomes

Cited by 11 publications

References 147 publications

Evaluating the variation in the projected benefit of community-wide mass treatment for schistosomiasis: Implications for future economic evaluations

Evaluating the variation in the projected benefit of community-wide mass treatment for schistosomiasis: Implications for future economic evaluations

Who acquires infection from whom and how? Disentangling multi-host and multi-mode transmission dynamics in the ‘elimination’ era

Neglected tropical diseases in the genomics era: re-evaluating the impact of new drugs and mass drug administration

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