Figure 1
From: Modelling effectiveness of herd level vaccination against Q fever in dairy cattle
Flow diagram describing the modelled spread of C. burnetii within a cattle herd. The health states are the following: S, non-shedder apparently susceptible cow, I
1
, shedder which still has the possibility to eliminate the bacterium and to become S again, I
2
, shedder which no longer has the possibility to become S again, I
3
, shedder which no longer has the possibility to become S again and sheds in milk in a persistent way, C
1
, non-shedder but still infected individual and C
2
, non-shedder which was C
1
in the past but eliminated the bacterium. The V
e
states (SV
e
, I
1
V
e
, I
2
V
e
, I
3
V
e
, C
1
V
e
and C
2
V
e
) are defined in the same way as S, I
1
, I
2
, I
3
, C
1
and C
2
respectively, except that these animals have been vaccinated when susceptible and non pregnant and are then assumed "vaccinated in an effective way" (V
e
). I and IV
e
cows are in the subcategory m if they shed in milk only, mf if they shed in vaginal mucus/faeces only and mmf if they shed in milk and vaginal mucus/faeces. E represents the environmental bacterial load and p, the probability of infection or reinfection for non V
e
individuals, is equal to 
. p
v
is the probability of infection or reinfection for V
e
individuals, which is a fraction of p. The other model parameters are presented in Additional file 1: Table S1. ε
1
, ε
2
, ε
3
, ε
1
V
e
, ε
2
V
e
and ε
3
V
e
are the quantities of bacteria shed during a time step by an individual I
1
, I
2
, I
3
, I
1
V
e
, I
2
V
e
and I
3
V
e
respectively and contaminating the environment. For a any shedder, ε represents the sum, for each shedding route, of the quantity of bacteria released, Qty, times ρ, its fraction reaching the herd environment.