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. 2013 Aug 1;7(8):e2346. doi: 10.1371/journal.pntd.0002346

Table 1. Estimates of the parameters used in our dynamic HIV-FGS model (Figure 1).

Variable Meaning (units) Prior distribution [ref] Posterior distribution: median (95% CI)
Inline graphic Annual growth rate rural population 0.034 [29] N/A
Inline graphic Duration of sexual activity (year-1) 1/35 N/A
Inline graphic Enhanced HIV transmission due to FGS Uniform(0,20) 5.9 (3.8–9.1)
Inline graphic Probability of FGS given childhood infection Uniform(0.33,0.75) [8] 0.47 (0.38–0.56)
Inline graphic Probability of acquiring FGS during adulthood Uniform(0.005,0.05) 0.008 (0.006–0.009)
Inline graphic Duration of HIV infection (years) Uniform(7.5,12.5) [33, 48] 10.7 (8.1–12.1)
Inline graphic Number of sex acts in partnerships per year for high-risk group Uniform(15,150) [48] 128 (95–148)
Inline graphic Number of sex acts in partnerships per year for low-risk group Uniform(50,248) [48] 69 (28–137)
Inline graphic HIV transmission rate per sex act Uniform(0.0006,0.004) [23], [39] 0.0022 (0.0009–0.003)
Inline graphic Mixing between sexual risk groups Uniform(0.2,0.9) [49] 0.44 (0.22–0.62)
Inline graphic Extent to which males determine the pattern of sexual partnerships formation Uniform(0.2,0.8) [48] 0.67 (0.50–0.78)
Inline graphic Initial partner change rate: women (year-1) Triangular(0.66,2.4,0.9) [48] 1.27 (0.7–2.2)
Inline graphic Initial partner change rate: men (year-1) Triangular(1.1,3,1.2) [48] 1.9 (1.2–2.8)
Inline graphic Fraction of women in high-risk group Uniform(0.05,0.6) [48] 0.20 (0.15–0.24)
Inline graphic Fraction of men in high-risk group Uniform(0.10,0.75) [48] 0.34 (0.22–0.49)
Inline graphic Relative rate of partner change: high-risk versus low-risk group Uniform(1,100) [48] 10.7 (2.5–21.8)
Inline graphic Reduction rate of partner change Uniform(1,50) 6.5 (3.5–9.0)
Inline graphic Year HIV epidemic starts Uniform(1978,1985) [48,50] 1981 (1980–1982)

These parameter estimates produced the best fit of our dynamic model to epidemiological data for HIV and FGS prevalence and co-infection among rural Zimbabwean women [3], [7]. The dynamic model was fit to these data using a Markov Chain Monte Carlo method, which allowed us to calculate distributions of possible values for each of these parameters. We present here the mean of these distributions and their associated 95% credible intervals. The Brooks-Gelman-Rubin (BGR) method was used to monitor convergence of iterative simulations. Convergence was achieved when the upper limit of the credible interval of the BGR diagnostic statistic for a given parameter <1.2 [51].