Tracing movements in a disease outbreak
( This is usually more relevant to farm outbreaks )
On the farm The initial farm visit should include collection of data of recent movements ( traces ) onto or off the farm . Movements to consider will depend on the disease organism ( if known ) and how it is spread . Potential movements to investigate include aquatic animals ( all stages of life , live and dead ), water , vehicles , wildlife , feed , humans and equipment ( including boats ).
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Indirect transmission or spread
• Water droplets
• Dust > 5 microns
Airborne
• Birds , aquatic mammals
• Other aquatic species e . g . sea lice
Mechanical or biological vector
Aquatic animal
Vehicle ( Fomites )
• Vehicles e . g . boats or trucks
• Personnel e . g . staff and visitors
• Equipment e . g . brush , net
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Vertical
• Spawning
Direct transmission or spread
Exposure via water
• Direct contact with other infected animals
• Contact with vomit / faeces
• Cannibalism
• Contact with infected processing waste
• Incoming infected water
Figure 7 . Potential sources for infectious diseases in an aquatic setting ( adapted from Oidtmann et al , 2013 ) see “ References ” on page 78 .
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