Critical level of condom use (<i>C_c</i>) predicted to prevent self-sustaining GC/CT and HIV transmission for the pair (A to D), classical uncalibrated (E to H), and classical model following calibration of <i>π</i> to the pair model output (I to L).

<p>The horizontal axes give partnership length in days while the vertical axes give gap length in days. <i>C_c</i> values are denoted by a gradient of colours as indicated; values of 0% demarcate the most extreme combination of partnership and gap lengths which supports self-sustaining transmission, while values above 100% (up to a theoretical maximum of 111% since condoms are assumed to be only 90% effective in preventing transmission) show partnership and gap combinations where consistent condom use is insufficient to prevent self-sustaining transmission.</p

Predictions from the classical and pair model formulations for the steady-state <i>π^s</i>of GC/CT (A and B), and the peak <i>π^p</i> of HIV with and without cofactor enhancement (C and D).

<p>The horizontal axes give partnership length in days while the vertical axes give <i>π</i>. The different lines denote predictions from using gap lengths () of 1 day, 7 days, 30 days and 90 days. The inset in each figure magnifies crossover point, if any, in the region where the classical and pair models diverge in <i>π</i> predictions. Models in (A) and (C) are unable to provide predictions at a gap length of 90 days.</p

Data from Lycke et al. [45] on case contact pairs for gonorrhoea and Chlamydia

1<p>Chlamydia.</p>2<p>Gonorrhoea.</p

Model parameters.

<p>Model parameters.</p

Absolute difference in predicted critical level of condom use (Abs(Δ<i>C_c</i>)) for GC/CT and HIV with and without cofactor enhancement (A to D), with its corresponding adjustment factor, (E to H).

<p>The horizontal axes give partnership length in days while the vertical axes give gap length in days. Abs(Δ<i>C_c</i>) is computed from the absolute difference in the corresponding values from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039575#pone-0039575-g002" target="_blank">Figure 2</a>. Coloured bars in the left (A to D) and right (E to H) panels give the values of Abs(Δ<i>C_c</i>) and by the respective gradient of colours.</p