Proceedings of the 10th International Colloquium on Paratuberculosis

For each year, a prior probability <strong>of</strong> MAP infection in <strong>the</strong> population was based on <strong>the</strong>
estimated probability from <strong>the</strong> previous year combined with <strong>the</strong> annual risk <strong>of</strong> introducing
MAP infection in <strong>the</strong> population. For 2005, <strong>the</strong>re were no previous estimate available and
<strong>the</strong>refore a probability <strong>of</strong> 0.5 (i.e. a non-informative estimate between 0 = “not infected” and 1
= “infected”) was chosen. The risk <strong>of</strong> introduction was based on <strong>the</strong> number on new imports
related to <strong>the</strong> historical relationship between number <strong>of</strong> cases and imports. The posterior
probability <strong>of</strong> MAP infection from each year was <strong>the</strong>n calculated based on <strong>the</strong> prior
probability <strong>of</strong> infection and <strong>the</strong> value <strong>of</strong> <strong>the</strong> new surveillance activities.
RESULTS AND DISCUSSION
Calculations <strong>of</strong> <strong>the</strong> sensitivity <strong>of</strong> different surveillance components, <strong>the</strong> sensitivity <strong>of</strong> <strong>the</strong>
surveillance system and <strong>the</strong> probability <strong>of</strong> freedom from MAP infections at <strong>the</strong> end <strong>of</strong> 2008
are underway. Additional data, such as results from a recently initiated sampling programme
at abattoirs may also be included in <strong>the</strong> final model.
ACKNOWLEDGEMENTS
The authors wish to thank <strong>the</strong> Swedish Board <strong>of</strong> Agriculture, <strong>the</strong> Swedish Animal Health
Services and <strong>the</strong> Swedish Dairy Association for collaboration and providing information from
<strong>the</strong>ir respective databases. In special, we are grateful to Ulrika Rockström for sharing and
explaining data from her previous investigations and Göran Bölske for literature and expert
opinion about test accuracy.
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