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Table 2 Definitions of model parameters and symbols. We estimated the model parameters R 0 (0), S ( a ) , S ˜ γ ( a ) and g γ (a) for each flock individually

From: Breeding with resistant rams leads to rapid control of classical scrapie in affected sheep flocks

Symbol: Interpretation:
R 0 (0) The basic reproduction number in the flock just before the start of the breeding programme
S(a) Survival function for non-infected animals
S ˜ γ ( a ) Survival function for infected animals of genotype γ
g γ (a) Relative susceptibility to infection of an animal of age a and genotype γ. It is determined by the parameters p γ and α below.
β(τ) Level of infectiousness of an animal that acquired scrapie infection a time τ ago (τ = incubation stage of time since infection)
fγ(t,a) Genotype distribution in the flock as a function of time
R 0 (t) The basic reproduction number in the flock as a function of time. It is determined by all parameters listed in the rows above.
p γ Probability of becoming infected in a certain year conditional on not having become infected before.
α Age-dependency parameter
λ Force of infection
Q γ (a) The uninfected proportion of animals of age a and genotype γ