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Publication type: Doctoral Thesis

Year: 2003

Author(s): Dangl, T

Title: Ein dynamisches State-Transition Modell zur Simulation von Maul- und Klauenseuche Epidemien.

Source: Dissertation, Vet. Med. Univ. Wien, pp. 101.


Advisor(s):

Rubel Franz


Project(s): MATHEPI - Development and Application of Mathematical Models in Veterinary Epidemiology


Abstract:
The objective of this thesis was to describe a dynamic state-transition model for foot-and-mouth disease (FMD) epidemics. Based on a Markov-chain, the model exists of five different health-states: 1. susceptible, 2. latent infected, 3. incubating-infectious, 4. diagnosed (confirmed case of FMD) and 5. culled herds. The following aspects of an FMD outbreak are taken into account: the problem of the hidden spread before the first case is diagnosed (silent development of FMD), the intra-herd evolution of the disease, the contamination of susceptible herds (the actual epidemic process) and the control strategy. On modelling disease control, the efficiency of two different strategies can be evaluated: stamping out (slaughter of all animals in the infected premises) and slaughter of dangerous contacts (the cull is extended to healthy herds that may have been contaminated). The model was validated with the FMD epidemic in Great Britain 2001: the correlation between the observed and calculated periodic incidences was 0,95 (Pearson correlation coefficient). The comparison of the simulated epidemic with the observed one showed following results: the model calculated 2.058 cases and a duration of 29 weeks, against 2.030 observed cases and an observed duration of 33 weeks. Concerning the total number of culled herds, the model estimated 9.194 culls against 9.585 perfomed ones. This means, that the model performance is sufficient to describe an epidemic of FMD.

Keywords:
control of epidemics / foot-and-mouth disease / mathematical modelling / process-models / state-transition model / veterinary epidemiology


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