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'Timeline' for
an FMD Outbreak
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An epidemiological team usually consists of :
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one authorised veterinarian of the National Veterinary
Authority who has received specialist training in FMD
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one expert in the epidemiology of FMD, usually from
the National Reference Laboratory for FMD
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a laboratory technician to assist with collection of
samples
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an assistant to help with handling and restraint of
animals
Role of the epidemiology team
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To identify the likely origin of infection (tracing
back)
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To identify likely spread of infection (tracing forward)
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Prioritise
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Investigations on the IP
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examine all animals
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for all affected animals record
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species
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number
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age of oldest lesion
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collect epithelium from a representative number of
animals
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collect blood and milk samples, if appropriate
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Identifying spread of virus
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identify period during which virus was being shed
from age of lesions, remember virus shedding starts BEFORE lesions
appear
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identify all movements off the premises during the
period of virus shedding and prioritise
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susceptible animals
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susceptible animal products (milk, meat, faeces)
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people who have had contact with animals
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equipment, including vehicles
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go back as long as age of oldest lesion + 21 days
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Identifying the origin of infection
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examine all animals on the holding and estimate the
number with clinical signs
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'age' lesions of all affected animals, especially
group with oldest lesions
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add one incubation period (2 -14 days) to the age
of the oldest lesion to derive which infection might have entered
the farm
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examine all movements onto and off the premises to
identify possible sources of infection
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remember the 'index case' might have been missed and
it may be necessary to go back further than 14 days before the first
appearance of clinical signs
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Constructing a 'time line' of events and their earliest
and latest possible occurrence can be helpful in assessing the risks
posed by movements onto and off the premises.
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