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Time frame
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Species to be tested
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In each country, all the species considered in this Opinion, except fallow deer (Eurasian tundra reindeer, Finnish (Eurasian) forest reindeer, moose, roe deer, white‐tailed deer and red deer), should be part of the surveillance system, unless a subset of these species is selected based on the outputs of national RA Prior to the implementation of the surveillance activities, a preliminary characterisation of the geographical distribution, abundance biologically based spatial subdivision, relative to the selected national cervid population, is needed
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In each country, all the species considered in this Opinion, except fallow deer (Eurasian tundra reindeer, Finnish (Eurasian) forest reindeer, moose, roe deer, white‐tailed deer and red deer), should be part of the surveillance system, unless a subset of these species is selected based on the outputs of national RA Prior to the implementation of the surveillance activities, a preliminary characterisation of the geographical distribution, abundance biologically based spatial subdivision, relative to the selected national cervid population, is needed
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Sampling units
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As sampling frames are not available, the design is based on the testing of animals (subunits) from geographically based ‘primary sampling units’ (PSU)
PSU are geographical areas defined by each country using a geographical criterion that has to be based:
On the population density of the selected species, i.e. areas in which aggregation of animals of a certain species in a certain period of the year is observed, or On natural barriers and presence/absence of the species if no aggregation is observed for a species, or On territorial hunting statistics.
For example, in the case of semidomesticated reindeer, siida in Norway and sameby in Sweden may be considered the correct level of aggregation to define the PSU. For wild cervids, each of the 23 different wild reindeer populations in Norway could be considered a PSU
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Farms or other captive wildlife facilities |
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Aims
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The surveillance system should have a two‐fold aim:
Detection:
this applies to countries where CWD has not yet been detected confirmation or exclusion of the presence of disease (i.e. detection of at least one affected animal; answer to a yes/no question); emphasis is on enhancing the probability of detection by focusing on high risk animals
PSU prevalence estimation:
This applies to Norway, and to any of the concerned countries within which CWD is detected At PSU level (i.e. not at individual animal level): estimation of the prevalence (proportion of positive out of the tested PSU; measure of disease frequency) and geographical spread; emphasis is on enhancing the validity of the estimates based on random sampling of PSU
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The surveillance system should have a twofold aim:
Detection:
this applies to countries where CWD has not yet been detected confirmation or exclusion of the presence of disease (i.e. detection of at least on one affected animal; answer to a yes/no question); emphasis is on enhancing the probability of detection by focusing on high risk animals
Farm prevalence estimation:
This applies to Norway, and to any of the concerned countries within which CWD is detected At farm‐level (i.e. not at individual animal level): estimation of the prevalence (proportion of positive out of the tested farms; measure of disease frequency) and geographical spread emphasis is on enhancing the validity of the estimates based on random sampling of farms
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Target groups
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Animals more than 12 months of age
AND any of the following:
animals killed because sick or in poor body condition and not fit for human consumption hunted or slaughtered animals considered not fit for human consumption road/predator kills found dead
Sampling of semidomesticated reindeer may be concentrated seasonally during the period/s of maximal aggregation of animals
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Animals more than 12 months of age
AND any of the following:
animals killed because sick or in poor body condition and not fit for human consumption found dead
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Sampling design
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Two‐stage sampling aiming at testing at a national level a total of 3,000 animals of all or the subset of selected species over the 3‐year period, which corresponds to an overall design prevalence at a population level of 0.1% and a 95% confidence level.
For the first stage, up to 100 PSU should be selected for surveillance over a 3‐year period using a random sampling approach, which corresponds to a design prevalence of 3% and a 95% confidence level. The random sampling will ensure the geographical representativeness; For the second stage (within each PSU), a convenience sample of 30 animals of all or the subset of selected species as defined above should be collected from the target groups (listed above), which corresponds to a design prevalence of 10% and a 95% confidence level. If a country defines less than 100 PSUs in its territory, a compensating increase in the second stage sample size should be applied, based on all or the subset of selected species, in order to meet the proposed overall design prevalence at a population level of 0.1% and a 95% confidence level, over the 3‐year period. The target sample sizes at PSU and animal levels together allow the estimation of prevalence with high precision considering the target population as the high‐risk animals
PSU‐level and animal‐level sensitivity/specificity are assumed to be equal to 100%
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Two‐stage sampling aiming at testing at a national level a total of 3,000 animals of all or the subset of selected species over the 3‐year period, which corresponds to an overall design prevalence at a population level of 0.1% and a 95% confidence level.
For the first stage, up to 100 PSU (farms) should be selected for surveillance over a 3‐year period using a random sampling approach, which corresponds to a design prevalence of 3% and a 95% confidence level. The random sampling will ensure the geographical representativeness. For the second stage (within each farm), a convenience sample of 30 animals of all or the subset of selected species as defined above should be collected from the target groups (listed above), which corresponds to a design prevalence of 10% and a 95% confidence level. If a country has less than 100 farms in its territory, a compensating increase in the second stage sample size should be applied, based on all or the subset of selected species, in order to meet the proposed overall design prevalence at a population level of 0.1% and a 95% confidence level, over the 3‐year period. The target sample sizes at farm and animal levels together allow the estimation of prevalence with high precision considering the target population as the high‐risk animals
Farm‐level and animal‐level sensitivity/specificity are assumed to be equal to 100%
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Tissue to be collected
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