Do fatal infectious diseases eradicate host species?

Area of Science:

• Epidemiology
• Mathematical Biology
• Ecology

Background:

• Understanding host extinction dynamics is crucial in epidemiological and ecological modeling.
• Incidence functions, which describe disease transmission rates, play a key role in these dynamics.

Purpose of the Study:

• To analyze the association between different classes of incidence functions and host extinction in simple SI (Susceptible-Infective) epidemic models.
• To evaluate the fit of these incidence functions to experimental data from salamander larvae infections.

Main Methods:

• Theoretical analysis of SI epidemic models with three classes of incidence functions: weakly upper density-dependent, power, and homogeneous.
• Comparison of model predictions with laboratory infection experiments using salamander larvae.

Main Results:

• Weakly upper density-dependent incidences are not associated with host extinction.
• Power incidences (0 < power < 1) are linked to initial-constellation-dependent host extinction.
• Homogeneous and power incidences can lead to global host extinction or host survival depending on parameter values.

Conclusions:

• The choice of incidence function significantly impacts the potential for host extinction in epidemic models.
• Experimental data from salamander larvae infections are consistent with power and certain density-dependent and homogeneous incidence functions, highlighting the need for careful model selection.