A) Critical treatment efficacy for SR and non-SR dynamics and different treatment intervals.

<p>B) Evolution of worm burden in children under annual treatment with and without sexual reproduction dynamics (default parameter values and R₀ = 2) C) Time series showing effect of different intervention frequencies with same annual treatment rate. D) Minimum number of treatment rounds necessary to achieve elimination (with SR) as a function of R0 and the interval between treatments.</p

A) Solutions of equations (1–2), without age structure, both with and without mating probability factor φ.

<p>Broken lines represent unstable solutions [Inset: Mating probability factor φ as a function of mean worm burden]. B) Time series for mean worm burden in children and adults and reservoir content in response to annual treatment.</p

Dependence of growth rate, k, on A) R₀ and effective treatment, γ; B) contribution of children to parasite reproduction, rc, and effective treatment; C) relative reservoir timescale, ε, and effective treatment.

<p>D) Extinction point for parasite for different values of ε. [For C, R₀ = 2.5 and D, r_c = 1].</p

Dimensional and non-dimensional model parameters with default values used in all calculations (unless otherwise stated).

<p>Dimensional and non-dimensional model parameters with default values used in all calculations (unless otherwise stated).</p

Cross-sectional surveys of the mean intensity of infection in different age groupings for <i>A</i>. <i>lumbricoides</i> (A), <i>T</i>. <i>trichiura</i> (B), and hookworm (C) based on worm expulsion studies.

<p>These are typical age intensity profiles for the three most important STH species, where the colours denote the age groupings: pre-SAC (blue), SAC (red), and adults (orange). Data for A from [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003897#pntd.0003897.ref025" target="_blank">25</a>], data for B [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003897#pntd.0003897.ref026" target="_blank">26</a>], and data for C [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003897#pntd.0003897.ref027" target="_blank">27</a>]. The inset in Graph C represents five worm expulsion studies of <i>Necator americanus</i> showing consistent patterns in a rise in burden with age in different geographical locations [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003897#pntd.0003897.ref028" target="_blank">28</a>].</p

Impact of different treatment stratgies on the mean number of worms in different age groupings.

<p>The coloured lines represent different treatment strategies: green—annual community-wide MDA (75% coverage of all age groupings (pre-SAC, SAC, and adults) and 95% drug efficacy); red—biannual age group targeted MDA (pre-SAC and SAC with 75% coverage and 95% drug efficacy); and blue—annual age group targeted MDA (pre-SAC and SAC with 75% coverage and 95% drug efficacy). Graphs A–C and D–F correspond to Hookworm and <i>Ascaris</i> respectively. Graphs A and D record the overall mean number of worms across all ages. Graphs B and E record the mean number of worms in children (pre-SAC and SAC, 2–15-year-olds). Graphs C and F record the mean number of worms in adults (>15 year olds). Calculations based on a basic reproductive number, R_o, of 2.5 (medium to high transmission setting). Model parameters described in [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003897#pntd.0003897.ref013" target="_blank">13</a>].</p