Figure 1.

A) States and transitions for the model of blood transfusion in the absence of an infection. B) Routes of infection. The arrows representing deaths out of all states are omitted. Paths of donor exclusion are plotted by dotted arrows. S₀₀, nonrecipients who do not donate; S₀₁, nonrecipients who donate; S₀₂,nonrecipients who are excluded from donating; S₁₀₀,recipients who do not donate; S₁₀₁, recipients who become excluded from donating; S₁₁₀, recipients who donate; S₁₁₁, recipients who become excluded from donating; S₁₂, recipients who are excluded from donating. Indices replaced by a dot (panel B) represent all other possible states (e.g., S_0• represents S₀₀, S₀₁, or S₀₂).