A biological model of scabies infection dynamics and treatment informs mass drug administration strategies to increase the likelihood of elimination

M. J. Lydeamore, P. T. Campbell, D. G. Regan, S. Y.C. Tong, R. M. Andrews, A. C. Steer, L. Romani, J. M. Kaldor, J. McVernon, J. M. McCaw

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Infections with Sarcoptes scabiei, or scabies, remain common in many disadvantaged populations. Mass drug administration (MDA) has been used in such settings to achieve a rapid reduction in infection and transmission, with the goal of eliminating the public health burden of scabies. While prevalence has been observed to fall substantially following such an intervention, in some instances resurgence of infection to baseline levels has occurred over several years. To explore the biology underpinning this phenomenon, we have developed a theoretical model of scabies life-cycle and transmission dynamics in a homogeneously mixing population, and simulate the impact of mass drug treatment strategies acting on egg and mite life cycle stages (ovicidal) or mites alone (non-ovicidal). In order to investigate the dynamics of the system, we first define and calculate the optimal interval between treatment doses. We calculate the probability of eradication as a function of the number of optimally-timed successive treatment doses and the number of years over which a program is run. For the non-ovicidal intervention, we first show that at least two optimally-timed doses are required to achieve eradication. We then demonstrate that while more doses over a small number of years provides the highest chance of eradication, a similar outcome can be achieved with fewer doses delivered annually over a longer period of time. For the ovicidal intervention, we find that doses should be delivered as close together as possible. This work provides a platform for further research into optimal treatment strategies which may incorporate heterogeneity of transmission, and the interplay between MDA and enhancement of continuing scabies surveillance and treatment strategies.
    Original languageEnglish
    Pages (from-to)163-173
    Number of pages11
    JournalMathematical Biosciences
    Volume309
    Issue numberMarch
    Early online date24 Aug 2018
    DOIs
    Publication statusPublished - Mar 2019

    Fingerprint

    Scabies
    scabies
    Biological Models
    Infection
    Elimination
    Dose
    Likelihood
    Drugs
    drugs
    Life cycle
    Mites
    dosage
    Life Cycle Stages
    infection
    Pharmaceutical Preparations
    Drug therapy
    Sarcoptes scabiei
    Public health
    Life Cycle
    Infectious Disease Transmission

    Cite this

    Lydeamore, M. J. ; Campbell, P. T. ; Regan, D. G. ; Tong, S. Y.C. ; Andrews, R. M. ; Steer, A. C. ; Romani, L. ; Kaldor, J. M. ; McVernon, J. ; McCaw, J. M. / A biological model of scabies infection dynamics and treatment informs mass drug administration strategies to increase the likelihood of elimination. In: Mathematical Biosciences. 2019 ; Vol. 309, No. March. pp. 163-173.
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    title = "A biological model of scabies infection dynamics and treatment informs mass drug administration strategies to increase the likelihood of elimination",
    abstract = "Infections with Sarcoptes scabiei, or scabies, remain common in many disadvantaged populations. Mass drug administration (MDA) has been used in such settings to achieve a rapid reduction in infection and transmission, with the goal of eliminating the public health burden of scabies. While prevalence has been observed to fall substantially following such an intervention, in some instances resurgence of infection to baseline levels has occurred over several years. To explore the biology underpinning this phenomenon, we have developed a theoretical model of scabies life-cycle and transmission dynamics in a homogeneously mixing population, and simulate the impact of mass drug treatment strategies acting on egg and mite life cycle stages (ovicidal) or mites alone (non-ovicidal). In order to investigate the dynamics of the system, we first define and calculate the optimal interval between treatment doses. We calculate the probability of eradication as a function of the number of optimally-timed successive treatment doses and the number of years over which a program is run. For the non-ovicidal intervention, we first show that at least two optimally-timed doses are required to achieve eradication. We then demonstrate that while more doses over a small number of years provides the highest chance of eradication, a similar outcome can be achieved with fewer doses delivered annually over a longer period of time. For the ovicidal intervention, we find that doses should be delivered as close together as possible. This work provides a platform for further research into optimal treatment strategies which may incorporate heterogeneity of transmission, and the interplay between MDA and enhancement of continuing scabies surveillance and treatment strategies.",
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    A biological model of scabies infection dynamics and treatment informs mass drug administration strategies to increase the likelihood of elimination. / Lydeamore, M. J.; Campbell, P. T.; Regan, D. G.; Tong, S. Y.C.; Andrews, R. M.; Steer, A. C.; Romani, L.; Kaldor, J. M.; McVernon, J.; McCaw, J. M.

    In: Mathematical Biosciences, Vol. 309, No. March, 03.2019, p. 163-173.

    Research output: Contribution to journalArticleResearchpeer-review

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    AU - Campbell, P. T.

    AU - Regan, D. G.

    AU - Tong, S. Y.C.

    AU - Andrews, R. M.

    AU - Steer, A. C.

    AU - Romani, L.

    AU - Kaldor, J. M.

    AU - McVernon, J.

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