Structure of the metapopulation model. H
y,a,z: proportion of birds in age class a, health state z of population y; V
x,z: proportion of vectors living at location x that have the health state z; μ
y,a: daily mortality rate of birds in age class a of population y; μ
v: vector daily mortality rate; λ
y,a: force of infection for hosts in age class a of population y; Tv: duration of viraemia in hosts; Tg
x: duration of gonotrophic cycle in vectors living at location x; Tx
x: duration of the extrinsic incubation period in vectors living at location incubation period in vectors living at location x; q
y,a: proportion of bites that occur on birds of population y and age class a; and p
y,a: proportion of viraemic birds in population y and age class a.