Table 1.
Definition of symbols and corresponding values used in the model SEI2D.
Figure 1.
The Canine Leishmaniasis model (SEI2D).
All dogs are born susceptible (S), and become infected at a rate ßS. Infected dogs go through a latent stage, after which a fraction evolves to an asymptomatic infection (Ia) while the remaining (1-p) evolve into the symptomatic state (Is). A small fraction of asymptomatic dogs may evolve to present signs of clinical disease, which is incorporated into the model through a relapse rate “λ”. The control program screens animals and, if laboratory positive, they move to class Da or Ds, where they remain until culling. Dz class holds those erroneously classified as positive.
Figure 2.
Prevalence of CVL in the higher endemicity area under four control programs differing in their target and in diagnostic test used.
“Is only” = control program targeting only symptomatic dogs, “Ia + Is” = targeting asymptomatic and symptomatic dogs; the number between parenthesis indicates the sensitivity of the diagnostic test.
Table 2.
Results of effective control of CVL with lower value of R0.
Figure 3.
Success of culling programs as a function of the basic reproduction number (R0), the screening effort (r) and the sensitivity of the diagnostic test (solid line = 80%; dotted line = 90%).
Figure 4.
Sensitivity analysis of parameters in Model SEI2D.
Box plots comparing parameter values that lead to prediction of successful control (prevalence <1) and failure (prevalence >1) considering a culling program with 4% screening effort and a diagnostic test with 80% sensitivity applied in an area with R0 = 1.41.