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. 2014 Aug 27;9(8):e106177. doi: 10.1371/journal.pone.0106177

Table 2. Parameters involved in the swine breeding farm model, with definitions, values and the sources of the values.

Model parameter Meaning Value Experimental source of value
DISEASE PARAMETERS
Inline graphic Direct transmission rate for sows and gilts 0.285 day−1 * (95% confidence interval: 0.091–0.9) Experimental data from Romagosa et al. [14] (mean of transmission values from non-vaccinated treatment group)
Inline graphic Indirect transmission rate for sows and gilts 0.0016 day−1 * Inline graphic Calculated from experimental data from Allerson et al. [10]
Inline graphic Direct transmission rate for piglets 0.218 day−1 * (95% confidence interval: 0.147–0.310) Experimental data from Allerson et al. [13] (transmission rate for non-vaccinated treatment group)
Inline graphic Indirect transmission rate for piglets 0.001 day−1 * Extrapolation from experimental data from Allerson et al. [10]; we assume Inline graphic
Inline graphic Direct transmission rate for piglets with maternal immunity 0.014 day−1 * (95% confidence interval: 0.001–0.061) Experimental data from Allerson et al. [13]
Inline graphic Indirect transmission rate for piglets with maternal immunity 0.00008 day−1 * Extrapolation from experimental data from Allerson et al. [10]
Inline graphic Reciprocal of average duration of latent/exposed period 1/2 day−1 Survey of swine influenza literature [24]
Inline graphic Reciprocal of average duration of infectious period (or recovery rate) 1/5 day−1 Survey of swine influenza literature [3], [14], [24], [26]
VACCINATION PARAMETERS
Inline graphic Direct transmission rate for pigs vaccinated with heterologous vaccine 0.0275 day−1 ** (95% confidence interval: 0.001–0.115) Experimental data from Romagosa et al. [14] (mean of transmission values from heterologously vaccinated treatment group)
Inline graphic Direct transmission rate for pigs vaccinated with homologous vaccine 0 day−1 ** (95% confidence interval: 0–0.052) Experimental data from Romagosa et al. [14] (no transmission occurred to pigs in homologously vaccinated treatment group)
Inline graphic Direct transmission rate for piglets when mother vaccinated with heterologous vaccine 0.174 day−1 ** (95% confidence interval: 0.118–0.246) Experimental data from Allerson et al. [13] (transmission rate from heterologously vaccinated treatment group)
Inline graphic Direct transmission rate for piglets when mother vaccinated with homologous vaccine 0.014 day−1 ** (95% confidence interval: 0.001–0.061) Experimental data from Allerson et al. [13] (transmission rate for homologously vaccinated treatment group)
Indirect transmission rates for each vaccine type are extrapolated from experimental data from Allerson et al. [10].
SWINE FARM PRODUCTION PARAMETERS
b Birth rate 12 live births per litter per sow (between days 2 and 7 each week) From expert knowledge of swine farm and PigCHAMP website (www.pigchamp.com/LinkClick.aspx?fileticket  = NMdM5F73gKE%3d&tabid = 115)
Inline graphic Natural death rate for sows and gilts (i.e. death rate not including culled animals) 0.0004 day−1 When combined with the cull, this value gives a total death rate of 50% per year (from expert knowledge of swine farm and PigCHAMP website)
Inline graphic Natural death rate for piglets 0.005 day−1 Corresponds to a death rate of 10% from birth to weaning (from expert knowledge of swine farm and PigCHAMP website)

The point/exact transmission values are used for the main simulations presented in this paper. “*” indicate transmission values that are varied across the range of their 95% confidence intervals for the model with variability in transmission. “**” similarly indicate the vaccination parameters that are varied for a sensitivity analysis.