Quantifying the relationship between within-host dynamics and transmission for viral diseases of livestock

Figures

• 

  Figure 1.. Within-host viral dynamics and transmission of foot-and-mouth disease virus in cattle. Each plot shows the viral titre (log10 tissue culture (TC) ID50 ml−1) in blood (blue), nasal fluid (orange) or oesophageal–pharyngeal (OP) fluid (yellow) for the animal (identified to the left of the first column): posterior median (solid black line) and 2.5th and 97.5th percentiles (shading) for the fitted virus curves given by equation (2.1). Open circles give the observed viral titres for each animal. Timing and outcome of experimental challenges are indicated by bars, which are coloured dark grey if the challenge was successful and light grey if it was not. The vertical black dashed lines indicate the onset of clinical signs.

• 

  Figure 2.. Within-host viral dynamics and transmission of swine influenza virus in pigs. Each plot shows the viral titre (log10 pfu ml−1) in nasal swabs for the animal (identified in the top right-hand corner): posterior median (solid black line) and 2.5th and 97.5th percentiles (green shading) for the fitted virus curves given by equation (2.1). Open circles give the observed viral titres for each animal. Timing and outcome of experimental challenges are indicated by bars, which are coloured dark grey if the challenge was successful and light grey if it was not.

• 

  Figure 3.. Within-host parameters for cattle infected with foot-and-mouth disease virus (FMDV) and pigs infected with swine influenza virus (SwIV): peak titre (log10 Vp; log10 tissue culture ID50 ml−1 for cattle, log10 pfu ml−1 for pigs); time of peak titre (Tp; days post infection); rate for the exponential viral growth phase (λg; per day); and rate for the exponential viral decay phase (λd; per day). Violin plots show the posterior density (shape), the posterior median (black circles) and the interquartile range (black line). Shape colour indicates the virus and the viral titre used in the model: FMDV and viral titre in blood (blue), nasal fluid (orange) or oesophageal–pharyngeal (OP) fluid (yellow); or SwIV and viral titre in nasal swabs (green).

• 

  Figure 4.. Summary transmission measures for cattle infected with foot-and-mouth disease virus (FMDV) and pigs infected with swine influenza virus (SwIV): reproduction number (R); generation time (Tg; days) and proportion of transmission before the onset of clinical signs (θ). Violin plots show the posterior density (shape), the posterior median (black circles) and the interquartile range (black line). Shape colour indicates the virus and the viral titre used in the model: FMDV and viral titre in blood (blue), nasal fluid (orange) or oesophageal–pharyngeal (OP) fluid (yellow); or SwIV and viral titre in nasal swabs (green). Because none of the SwIV-infected pigs showed clinical signs, θ was not calculated in this case.

• 

  Figure 5.. Summary transmission measures for foot-and-mouth disease virus (FMDV) in cattle and swine influenza virus (SwIV) in pigs and their dependence on within-host viral dynamics. Plots show the reproduction number (R; top row), generation time (Tg; middle row) or proportion of transmission before the onset of clinical signs (θ; bottom row) and their dependence on peak titre (log Vp), the time of peak titre (Tp), the rates during the exponential viral growth (λg) and decay (λd) phases and the transmission parameter (γ). Contours show the joint posterior density for the summary measure and the hierarchical (i.e. population-level) mean for the within-host parameter. Colour indicates the virus and the viral titre used in the model: FMDV and viral titre in blood (blue), nasal fluid (orange) or oesophageal–pharyngeal (OP) fluid (yellow); or SwIV and viral titre in nasal swabs (green). Black lines show the relationship between R or Tg and the within-host parameter as defined by equation (3.1) or (3.2), respectively, with the remaining parameters fixed at their posterior median values. Black crosses mark the posterior median for θ and the parameter. Because none of the SwIV-infected pigs…