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This summary outlines a qualitative risk assessment which has been completed to assess the risk of deer species in Great Britain becoming infected with chronic wasting disease (CWD) through legal trade from Scandinavia and North America. This considers the legal movement of animals, animal products and people. »Ê¹ÚÌåÓýapp risk is assessed as of November 2023.

Please note this is the executive summary only. To request the full risk assessment, please contact [email protected]ÌýÌý

»Ê¹ÚÌåÓýapp annual likelihood that a CWD prion will enter Great Britain through legal trade was considered very low (event is very rare but cannot be excluded) with medium uncertainty.

»Ê¹ÚÌåÓýapp annual likelihood of a susceptible animal being exposed to these prions ranged from negligible (event is so rare that it does not merit consideration) to very low with low to high uncertainty, depending upon the specific pathway and deer population considered (wild, farmed, or park deer).

»Ê¹ÚÌåÓýapp potential national consequences of a CWD incursion, given the possible animal welfare, trade, social, and economic effects, were considered major with medium ³Ü²Ô³¦±ð°ù³Ù²¹¾±²Ô³Ù²â. â¶Ä¯Â�

This is the fifth update of a risk assessment dating from 2012, which originally investigated the risk of incursion of CWD in Great Britain from the USA and Canada. »Ê¹ÚÌåÓýapp assessment was updated in March 2016 to include a new import pathway, cervid urine lures. In September 2016, a new update followed the report of CWD-like disease in wild reindeer in Norway, with 2 new entry pathways added (plants, trees and shrubs with root balls, and non-cervid animals, including working dogs). »Ê¹ÚÌåÓýapp risk assessment was further updated, in June 2017 and May 2018, following the identification of additional CWD cases among wild reindeer, moose, and red deer in Norway, and the first report of CWD in a wild moose in Finland, respectively. »Ê¹ÚÌåÓýapp fifth, most recent, update was finalised in November 2023. 

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Since the last update in May 2018, CWD has continued to spread throughout captive and free-ranging cervid populations in North America. At the time of the last update, it had been found among captive or free-ranging cervids in 24 US states and 2 Canadian provinces, but as of November 2023, this had risen to 32 US states and 4 Canadian provinces.  

In addition, further cases have been identified in 3 wild reindeer, 10 moose and 2 red deer in Norway and 2 wild moose in Finland. »Ê¹ÚÌåÓýapp disease has also been reported for the first time in Sweden, with 4 cases identified in the wild moose population there between 2019 and 2020. 

Chronic wasting disease can be broadly classified as classical (C-CWD) or atypical (A-CWD). »Ê¹ÚÌåÓýapp main distinction is the distribution of prions in the lymphoreticular system (LRS), particularly the lymph nodes and spleen. 

It is hypothesised that A-CWD may be associated with reduced (or absent) prion shedding, which may not be high enough to sustain natural transmission. However, there is high uncertainty around this, due to limited research. »Ê¹ÚÌåÓýapprefore, A-CWD was considered still within this risk assessment alongside C-CWD.ÌýÌý 

»Ê¹ÚÌåÓýapp following pathways were considered as part of the entry assessment:ÌýÌý

• live cervids 
• working dogs 
• scavenging birds 
• cervid meat 
• trophy items 
• hides, skins and leathers 
• urine lures 
• cervid manure 
• equipment, clothing or footwear 
• plants, trees and shrubs 
• hay and straw 
• animal feed 
• cervid germplasm 
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Any CWD prion strain in Scandinavian and North American cervids. 

Risk questions 

1) What is the annual likelihood of CWD prions from affected regions of Scandinavia and North America entering Great Britain?   �

2) What is the annual likelihood of a cervid within Great Britain being exposed to and infected with CWD ±è°ù¾±´Ç²Ô²õ?Ìý

3) What are the potential consequences of a CWD incursion into Great Britain?  �

Main findings 

Entry pathways 

Cervid meat, plants, shrubs and trees and animal feed were all considered to have a very low likelihood of importing CWD, with medium uncertainty.ÌýÌý

»Ê¹ÚÌåÓýappre was high uncertainty surrounding the likelihood of entry associated with hay and straw, cervid trophy items, working dogs and equipment. As the uncertainty was so high, an accurate estimation of the risk was not possible. »Ê¹ÚÌåÓýapprefore, these were considered non-negligible (high uncertainty). ‘Non-negligibleâ€� does not necessarily mean a high risk of entry, but indicates that while the risk is greater than negligible (so rare it does not merit consideration), it is not possible to give a more exact risk estimate.ÌýÌý

Scavenging birds, cervid urine lures, manure, live cervids, germplasm and ticks were all considered negligible risk (medium uncertainty). »Ê¹ÚÌåÓýapp risk estimated in this update was based on levels of trade with North America and Scandinavia as of November 2023, including trade restrictions such as the suspension of live deer imports and urine lures.ÌýÌýÌýÌý

Exposure pathways 

»Ê¹ÚÌåÓýapp annual likelihood of a susceptible animal in Great Britain being exposed to these prions was highest for hay and straw with a very low likelihood (high uncertainty). If a susceptible cervid in Great Britain was exposed to prions, then the likelihood of this causing a clinical case of CWD was considered high (occurs very often) with medium uncertainty.ÌýÌý

Consequence assessment 

A CWD incursion into Great Britain could have substantial animal health and welfare impacts in deer, including significant population declines, as have been seen in the USA. In turn, there could be significant disruption of rural tourism, sporting and farming operations in affected areas, as well as significant job losses and land contamination with CWD prions. Prions are challenging to control once introduced into an area, particularly if present in the wild animal population. »Ê¹ÚÌåÓýapp disease control costs involved in eradication are likely to be significant, requiring extensive testing and culling. »Ê¹ÚÌåÓýapp degree of trade restrictions on cervids and cervid products such as fresh meat are hard to quantify. »Ê¹ÚÌåÓýapprefore, the potential consequences of a CWD incursion, given the possible animal welfare, trade, social, and economic effects, were considered major (major impact for small population, systems significantly compromised and abnormal operation, if at all, high level of monitoring required) with medium ³Ü²Ô³¦±ð°ù³Ù²¹¾±²Ô³Ù²â. â¶Ä¯Â�

Key uncertainties 

Entry assessment 

»Ê¹ÚÌåÓýapp key uncertainties in entry assessment are:ÌýÌý

• the number of working dogs, such as hunting dogs, imported from North America or Scandinavia
• the quantity of cervid meat imported by travellers in luggage or vehicles from Norway, Finland, and Sweden
• frequency of movements between Great Britain and the CWD-affected areas of North America and Scandinavia by hunters, overseas and British tourists, and British service personnel, as well as the level of environmental contamination in these areas
• the efficacy of deer-proofing measures in growing areas for plants, trees and shrubs within Scandinavia and North America
• the ability of plant species other than grasses to bind, uptake, and transport CWD prions and the degree to which this may contribute towards CWD transmission under field conditions
• the ability of CWD prions to contaminate, survive, and transmit from hay and straw and the proportion of hay and straw imports which originate from CWD-affected areas of North America

Exposure assessment

»Ê¹ÚÌåÓýapp key uncertainties in exposure assessment are as follows: 

• differences in shedding and transmission between A-CWD and C-CWD
• potential exposure of wild and park deer in Great Britain to CWD prions through various sources, including contaminated soil, vegetation, animal feed and cervid meat
• the transfer of CWD prions via contaminated clothing and equipment
• the frequency of soil consumption among deer
• the minimum infectious dose 
• the susceptibility of British cervid species to different CWD strains

Consequence assessment 

»Ê¹ÚÌåÓýapp key uncertainty is consequence assessment is: 

• unknown trade restrictions due to an outbreak in Great Britain
• whether eradication or containment would be attempted