Blue tongue – A modelling examination of fundamentals – Seasonality and chaos
| Autor: | John H.M. Thornley, James France |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Statistics and Probability Blue tongue 040301 veterinary sciences Placenta Environment Biology Bluetongue Models Biological General Biochemistry Genetics and Molecular Biology 0403 veterinary science cvg.developer 03 medical and health sciences Pregnancy Statistics medicine Animals Computer Simulation cvg Logistic function General Immunology and Microbiology Ecology Applied Mathematics Early disease 04 agricultural and veterinary sciences General Medicine Seasonality medicine.disease Insect Vectors 030104 developmental biology Nonlinear Dynamics Modeling and Simulation Air temperature Female Seasons General Agricultural and Biological Sciences Constant (mathematics) Variable number Bluetongue virus |
| Zdroj: | Journal of Theoretical Biology. 403:17-29 |
| ISSN: | 0022-5193 |
| Popis: | A deterministic mathematical model is developed for the dynamics of bluetongue disease within a single farm. The purpose is to examine widely the possible behaviours which may occur. This is important because of the increasing impact of blue tongue due to global warming. The model incorporates a recently suggested modification of logistic growth for the vectors which can greatly affect early disease dynamics and employs a variable number of up to 10 sequential pools for incubating vectors and for incubating and infectious hosts. Ten sequential pools represent the possible loss of immunity of recovered hosts over a 3-year period. After formally describing the model, the impact of the two logistic growth scenarios considered is examined in Section 3.1. The scenarios are applied with parameters that give identical long-term consequences but the early dynamics can be greatly affected. In the two scenarios, the effect of varying the assumed constant birth rate (scenario 1) or constant mortality rates (scenario 2) is considered. If the recovered (and immune) hosts, are assumed to lose their immunity, then, given particular values of the host-vector coupling constants, the system can exhibit autonomous oscillations (Section 3.2). Seasonality is represented by air temperature, and it is assumed that air temperatures below a threshold can increase vector mortality (Section 3.3). Adding seasonal effects on mortality to the autonomous oscillations resulting from recovered and resistant hosts losing immunity can give rise to chaos (Section 3.4). This could help explain the unusual persistence and re-occurrence of the disease. Finally (Section 3.5), the roles of host birth and mortality rates in examined, particularly in relation to placental transmission of the virus to offspring. It is concluded that the latter does not make an appreciable contribution to disease dynamics. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect