Effect of the parameters on the model where the infection rate depends on the number of infected individuals in the population.

<p>(A) Regime followed according to the basic reproductive number of normal individuals () and duration of immunity (); (B) same as (A) but with (<i>q</i> = ρ = 1). The bold lines represent the threshold value at equilibrium, where the number of infected individuals is the same in a population consisting only of “avoiders” and in a population exclusively composed of “normal” individuals.</p

Detrimental effect of pathogen avoidance for non-lethal diseases.

<p>It is represented by the relative frequency (<i>r</i>, Y-axis) at which “avoider” individuals suffer classical infections compared to “normal” ones (when values are below one, avoiding the pathogenic agent is beneficial), according to the rate of infection by a pathogenic agent (X-axis). (A) For total immune periods of one year, avoiding the pathogenic agent is beneficial only for low infection rates. For high infection rates, both strategies tend to become equivalent since boosts to the immune system are almost systematic; (B) for lifelong immunity, avoiding the pathogenic agent is always a good strategy; and (C) considering a continuum in the total duration of immunity (in years) shows that “avoiders” can be more than six times more at risk of becoming sick compared to “normal” individuals. The threshold where both strategies are equivalent (<i>r</i> = 1) is represented with a dashed line (A) or with a bold red line (C).</p

Impact of pathogen avoidance when the infection rate depends on the number of infected individuals in the population.

<p>We plot here the equilibrium proportion of infected individuals in the host population (Y-axis) according to the proportion of “avoiders” (<i>p_A</i>, X-axis). Note that here the transmission rate of the pathogen can be derived from the value of through the formula . (A) An example of a situation where the system follows regime A (, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002299#s3" target="_blank">Results</a>: Model where exposure depends on infected individuals, for description of regimes); (B) an example of a situation where the system follows regime A-n (); (C) an example of a situation where the system follows regime N-a () and (D) an example of a situation where the system follows regime N ().</p

Flow diagram of the five classes of the modified <i>SIR</i> model.

<p>Arrows represent the transitions, with their associated rates. Transition rates in red are the only ones that differ between “avoiders” and “normal” individuals.</p

Distribution of the pathogen’s basic reproduction number (R₀) for each of the six vector-borne diseases considered.

<p>(<b>A</b>) Diseases with only human hosts: human African trypanosomiasis (HAT), dengue (DEN) and malaria (MAL). (<b>B</b>) Diseases with non-human hosts: Chagas disease (CD), Japanese encephalitis (JE), and visceral leishmaniasis (VL). Distributions were obtained from 10,000 simulations for each disease.</p

Distribution of the prevalence of infected and recovered humans when some immigrant vectors are infectious ().

<p>Black and grey bars give the prevalence of infectious () and recovered () humans, respectively. Numbers above bars give (if any) the percentage of simulations leading to prevalence larger than 5%. Distributions were obtained from 10,000 simulations for each disease.</p

Distribution of the prevalence of infectious and recovered humans when no immigrant vector is infectious ().

<p>Black and grey bars give the prevalence of infectious () and recovered () humans, respectively. Numbers above bars give (if any) the percentage of simulations leading to prevalence larger than 5%. Distributions were obtained from 10,000 simulations for each disease.</p

Microsatellites and sample locations

Multilocus microsatellite genotypes, location and sampling year of n=271 feral cats on the Kerguelen Archipelag

Sensitivity of the basic reproduction number (R₀) to vector’s demography and feeding rates, and to pathogen’s transmissibility and virulence.

<p>All six vector-borne diseases appear on the same graph. Squares correspond to diseases with only human hosts: human African trypanosomiasis (HAT), dengue (DEN) and malaria (MAL). Circles correspond to diseases with non-human hosts: Chagas disease (CD), Japanese encephalitis (JE), and visceral leishmaniasis (VL). Larger symbols correspond to the key determinants of the variations of R₀ (see main text for comments). Sensitivities were calculated from 10,000 simulations for each disease.</p

Pearson's chi-square tests, corrected chi-square tests and logistic regressions for the search of viruses' interactions.

<p>Pearson's chi-square tests, corrected chi-square tests and logistic regressions for the search of viruses' interactions.</p