Stability and bifurcation analysis of epidemic models with saturated incidence rates: An application to a nonmonotone incidence rate

We analyze local asymptotic stability of an SIRS epidemic model with a distributed delay. The incidence rate is given by a general saturated function of the number of infective individuals.Our first aim is to find a class of nonmonotone incidence rates such that a unique endemic equilibrium is alway...

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Main Authors: Yoichi Enatsu, Yukihiko Nakata
Format: Article
Language:English
Published: AIMS Press 2014-02-01
Series:Mathematical Biosciences and Engineering
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Online Access:https://www.aimspress.com/article/doi/10.3934/mbe.2014.11.785
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author Yoichi Enatsu
Yukihiko Nakata
author_facet Yoichi Enatsu
Yukihiko Nakata
author_sort Yoichi Enatsu
collection DOAJ
description We analyze local asymptotic stability of an SIRS epidemic model with a distributed delay. The incidence rate is given by a general saturated function of the number of infective individuals.Our first aim is to find a class of nonmonotone incidence rates such that a unique endemic equilibrium is always asymptotically stable.We establish a characterization for the incidence rate, which shows that nonmonotonicity with delay in the incidence rate is necessary for destabilization of the endemic equilibrium. We further elaborate the stability analysis for a specific incidence rate. Here we improve a stability condition obtained in [Y. Yang and D. Xiao, Influence of latent period and nonlinear incidence rate on the dynamics of SIRS epidemiological models, Disc. Cont. Dynam. Sys. B 13 (2010) 195-211], which is illustrated in a suitable parameter plane. Two-parameter plane analysis together with an application of the implicit function theorem facilitates us to obtain an exact stability condition. It is proven that as increasing a parameter, measuring saturation effect, the number of infective individuals at the endemic steady state decreases, while the equilibrium can be unstable via Hopf bifurcation. This can be interpreted as that reducing a contact rate may cause periodic oscillation of the number of infective individuals, thus disease can not be eradicated completely from the host population, though the level of the endemic equilibrium for the infective population decreases. Numerical simulations are performed to illustrate our theoretical results.
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spelling doaj-art-cc7b3df790a54e18983ed140e9dc9e9d2025-01-24T02:28:18ZengAIMS PressMathematical Biosciences and Engineering1551-00182014-02-0111478580510.3934/mbe.2014.11.785Stability and bifurcation analysis of epidemic models with saturated incidence rates: An application to a nonmonotone incidence rateYoichi Enatsu0Yukihiko Nakata1Graduate School of Mathematical Sciences, University of Tokyo, 3-8-1 Komaba Meguro-ku, Tokyo 153-8914Bolyai Institute, University of Szeged, H-6720 Szeged, Aradi vértanúk tere 1We analyze local asymptotic stability of an SIRS epidemic model with a distributed delay. The incidence rate is given by a general saturated function of the number of infective individuals.Our first aim is to find a class of nonmonotone incidence rates such that a unique endemic equilibrium is always asymptotically stable.We establish a characterization for the incidence rate, which shows that nonmonotonicity with delay in the incidence rate is necessary for destabilization of the endemic equilibrium. We further elaborate the stability analysis for a specific incidence rate. Here we improve a stability condition obtained in [Y. Yang and D. Xiao, Influence of latent period and nonlinear incidence rate on the dynamics of SIRS epidemiological models, Disc. Cont. Dynam. Sys. B 13 (2010) 195-211], which is illustrated in a suitable parameter plane. Two-parameter plane analysis together with an application of the implicit function theorem facilitates us to obtain an exact stability condition. It is proven that as increasing a parameter, measuring saturation effect, the number of infective individuals at the endemic steady state decreases, while the equilibrium can be unstable via Hopf bifurcation. This can be interpreted as that reducing a contact rate may cause periodic oscillation of the number of infective individuals, thus disease can not be eradicated completely from the host population, though the level of the endemic equilibrium for the infective population decreases. Numerical simulations are performed to illustrate our theoretical results.https://www.aimspress.com/article/doi/10.3934/mbe.2014.11.785nonlinear incidence ratehopf bifurcationlinearized stabilitydelay differential equation.epidemic model
spellingShingle Yoichi Enatsu
Yukihiko Nakata
Stability and bifurcation analysis of epidemic models with saturated incidence rates: An application to a nonmonotone incidence rate
Mathematical Biosciences and Engineering
nonlinear incidence rate
hopf bifurcation
linearized stability
delay differential equation.
epidemic model
title Stability and bifurcation analysis of epidemic models with saturated incidence rates: An application to a nonmonotone incidence rate
title_full Stability and bifurcation analysis of epidemic models with saturated incidence rates: An application to a nonmonotone incidence rate
title_fullStr Stability and bifurcation analysis of epidemic models with saturated incidence rates: An application to a nonmonotone incidence rate
title_full_unstemmed Stability and bifurcation analysis of epidemic models with saturated incidence rates: An application to a nonmonotone incidence rate
title_short Stability and bifurcation analysis of epidemic models with saturated incidence rates: An application to a nonmonotone incidence rate
title_sort stability and bifurcation analysis of epidemic models with saturated incidence rates an application to a nonmonotone incidence rate
topic nonlinear incidence rate
hopf bifurcation
linearized stability
delay differential equation.
epidemic model
url https://www.aimspress.com/article/doi/10.3934/mbe.2014.11.785
work_keys_str_mv AT yoichienatsu stabilityandbifurcationanalysisofepidemicmodelswithsaturatedincidenceratesanapplicationtoanonmonotoneincidencerate
AT yukihikonakata stabilityandbifurcationanalysisofepidemicmodelswithsaturatedincidenceratesanapplicationtoanonmonotoneincidencerate