For the spread of an infection without recovery we compare the properties of a model in which contacts are assumed to be instantaneous and every contact is with a new partner to a model with an explicit description of partnership formation and duration.
We investigate the dynamic behaviour at the beginning of the epidemic, the exponential growth phase and the endemic equilibrium in a population with a simple demographic process.
Comparisons are made with the assumption that the basic reproduction ratio Ro is equal for both models.
In a second step we introduce variable infectivity into both models and investigate how that interacts with the process of pair formation and partnership duration.
The main results are :
If partnership duration is taken into account, then (a) the prevalence may initially decrease, even if R0>1 ; (b) the exponential growth rate is lower than in a model without partnership duration ; (c) the endemic equilibrium is higher than in a model without partnership duration.
Furthermore we show that for a model with positive partnership duration for one value of R0 one might have more than one corresponding epidemic growth rate and endemic steady state.
This implies that one cannot estimate R0 from the endemic level without further information on the partnership process. (...)
Mots-clés Pascal : Développement maladie, Infection, Pouvoir infectant, Etude comparative, Modélisation, Régime dynamique, Epidémie, Interaction contact, SIDA, Virose, Formation couple, Homme, Immunopathologie, Immunodéficit
Mots-clés Pascal anglais : Disease development, Infection, Infectivity, Comparative study, Modeling, Dynamic conditions, Epidemic, Contact interaction, AIDS, Viral disease, Pair formation, Human, Immunopathology, Immune deficiency
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 98-0276181
Code Inist : 002B05C02D. Création : 27/11/1998.