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. 2022 Jan 24;20(1):e07121. doi: 10.2903/j.efsa.2022.7121
Sampling procedures Conclusions Recommendations
ToR 1
In the event of suspicion or confirmation
4.1.1.1 (Scenario 1) In the event of a suspicion of LSD in an establishment where animals of the listed species are kept. The clinical signs of LSD are very specific and the characteristic skin nodules are in most cases visible from a distance. Nevertheless, in the early stages of the disease, or in mild cases, they may not be detected unless gentle stroking or palpation of the animal's skin is undertaken.
The sensitivity of the clinical examination to identify animals with clinical signs varies, and the median value is estimated at 75%; while the specificity cannot be always assumed as 100%.
In animals with clinical signs of LSD, the diagnostic sensitivity of different PCR methods has been reported to be between 90.5% and 100% in blood and 95.5–100% in tissues, while the specificity ranges between 96.7% and 100% in blood and 100% in tissue. The individual clinical examination should focus primarily on those animals showing prominent skin nodules. The clinical examination should always include gentle stroking or palpation of the animal's skin.
Given the specificity of LSD skin nodules and the fact that the sensitivity of PCR is higher in tissues (skin and ophthalmic/oral/nasal discharges), laboratory testing to confirm or rule out the disease should be targeted to those animals with skin lesions first.
Collecting samples from several animals, and different types of samples from each animal (skin nodules, scabs, ophthalmic/nasal/oral swabs, blood) may increase the level of confidence to detect or rule out the disease and can prevent technical problems with sampling in the field (e.g. low quality of samples especially for skin nodules and difficulties with skin biopsy).
Assuming a specificity of the clinical examination of 99.9% and a sensitivity of 75%, at least two animals should be collected in an establishment with a prevalence of 1%, to ensure 95% confidence in detecting animals with clinical signs.
In cattle population where vaccination against LSD has been implemented, DIVA PCR methods is necessary for the distinction between field and vaccine virus strains.
4.1.1.2. (Scenario 2) For the purposes of the epidemiological enquiry as referred to Article 57 of Regulation (EU)2016/429 in an LSD officially confirmed establishment. Epidemiological enquiry
The epidemiological enquiry in an affected establishment may be supported by sampling procedures for the following purposes:
  • to estimate the prevalence of clinical signs within the affected establishment

  • to identify the virus and estimate the geographical origin of the disease

  • to estimate the length of time that the disease has been present in the establishment and the time of introduction

  • to conduct vector surveillance in the affected establishment and the surroundings to investigate the vectors involved.

Preventive Killing
Confirm and rule out the disease in case of preventing killing will be based on clinical and laboratory examination of the animals.
According to a model for the transmission of LSDV between farms (EFSA AHAW Panel, 2016), vaccination has a greater effect in reducing LSDV spread compared to any culling policy, even when low vaccine effectiveness is considered. When vaccination is evenly applied so that 95% of the farms are vaccinated with 75% of the vaccinated animals effectively protected, then total stamping out and partial stamping out result in a similar probability of eradicating the disease. It is important to understand that this conclusion is based on either virus introduction in a region with 95% already vaccinated farms, or in a region where 95% of the farms are vaccinated between 15 and 65 days after introduction of the virus (EFSA AHAW Panel, 2016).
Epidemiological enquiry
Clinical examination of all the animals to estimate the prevalence of clinical signs in the affected establishment.
Virus isolation and Partial or Whole genome sequencing to compare the virus with recently circulating viruses in other countries or regions and with vaccine strains.
Estimate the age of the lesions and search for the presence of antibodies in animals with clinical signs to estimate the time of introduction in the establishment.
Collect samples of vectors from animals and the environment of the affected establishment to obtain information on the presence, distribution and abundance of the vector species. Virus detection in the collected specimens by PCR methods will provide only an indication of the potential vectors involved with the transmission of the disease and will not imply their involvement in LSDV transmission and/or persistence. Further scientific research including well‐designed studies on the field and experimental trials, is necessary to better understand their role in the epidemiology of LSD.
Preventive Killing
In case of preventive killing, all the animals (or if not feasible a minimum sample of animals) should be clinically examined with a confidence level to detect or rule out the disease at least 95%, assuming low target (design) prevalence of the disease.
In case of preventive killing random sampling of blood and swabs for laboratory analysis by PCR. The sample size should be able to detect the disease with a confidence level of 95%.
The AHAW Panel considers that preventive killing in temporary and restricted zones in establishments with no clinical signs and without any evidence of the suspicion of the disease might not be the choice for LSD control since effective vaccines are available. Quick vaccination of all susceptible animals within these zones, to early reach a high level of immunity, would be the choice to halt the spread of the disease.
4.1.1.3. (Scenario 3) For granting a specific derogation from killing animals of the categories of article 13.2 of the Delegated Regulation in an LSD affected establishment. In an establishment affected by LSD, despite the infected animals confirmed by either laboratory tests or based on clinical signs, there might be animals which are in the incubation period of the disease (preclinical) and animals at subclinical status. The involvement of vectors to the transmission of the disease should be considered.
In early stages of the infection there is a window period during which the diagnostic tools (clinical examination or laboratory methods) may not be able to detect the disease. All the animals intended for derogation of killing should be subjected to thorough individual clinical examination.
Regular clinical examination should be carried out, preferably every day, for a period of at least the monitoring period (28 days) calculated forwards from the latest day a case was confirmed.
Sampling all the animals for laboratory examination, irrespectively the presence of clinical signs will be able to identify also infected animals without clinical signs. Sampling for laboratory examination can be repeated at any time but the last sampling should be carried out not earlier than 28 days (monitoring period) forwards the day of confirmation of the latest case.
Sampling for laboratory analysis of the animals should be carried out as described in Sections 4.1.1.1 and 4.1.1.2.
See also 1st scenario in Section 4.1.1.1 and 2nd scenario in Section 4.1.1.2 on sampling procedures.
The animals intended for derogation of killing should be treated with insecticide or repellent against the relevant vectors. Control of breeding sites and larval population of vectors in the establishment is recommended.
Whenever it is applicable keeping the animals in a vector protected establishment will contribute to further reduce the risk of LSD spread.
Vaccination of the healthy animals should be considered to further minimise the risk of spread.
4.1.1.4. (Scenario 4) For the animals of non‐listed species kept in an LSD affected establishment. In general, CaPVs are highly host specific and according to our current knowledge, limited data are available on the susceptibility of animal species other than Bos spp. and Bubalus spp. and there is no evidence on their involvement with LSD transmission.
Giraffe and impala experimentally infected by LSDV, demonstrated severe illness with typical symptoms and lesions of LSD and finally died while LSDV isolated from skin lesions.
LSDV nucleic acid was detected in skin samples collected from springbok antelopes in South Africa.
Antibodies against SPPV, GTPV and LSDV cannot be differentiated from each other by serological tests and their presence in animal species doesn't imply that these animals are able to transmit the disease.
Antibodies against CaPV have been detected in several antelope species in Africa in giraffes and African buffalos.
Giraffes, African buffalo, impalas and other antelope species are not natural inhabitants in European continent and their role on LSD transmission might not be significant
The available diagnostic methods for LSD may not be validated for these animals. Giraffes, African buffalos, impalas and other antelope species in case they are kept in an affected by LSD establishment, they should be monitored for clinical signs.
On the occurrence of clinical signs laboratory examination should be followed.
The lack of information on the performance of laboratory tests (sensitivity, specificity) in these animal species along with the lack of validation of the diagnostic methods in them will increase the uncertainty on the reliability of the sampling strategy.
See also 1st scenario in Section 4.1.1.1 and 2nd scenario in Section 4.1.1.2 on sampling procedures.
4.1.1.5. (Scenario 5) For wild animals of the listed species within the LSD affected establishment and its surroundings. Wild animals of listed species living in the surrounding area of the affected establishment are likely to be infected due to involvement of the haematophagous arthropods in the transmission of the disease.
The available diagnostic methods for LSD may not be validated for these animals. Surveillance of wildlife in the surroundings of an affected establishment may include visual inspection of these animals from distance and inspection of fallen stock and hunted animals to identify clinical signs compatible with LSD.
On the occurrence of clinical signs laboratory examination should be followed.
The lack of information on the performance of laboratory tests (sensitivity, specificity) in these animal species along with the lack of validation of the diagnostic methods in them will increase the uncertainty on the reliability of the sampling strategy.
See also 1st scenario in Section 4.1.1.1 for clinical examination and sampling for laboratory examination in case clinical signs are present.
See also 2nd scenario in Section 4.1.1.2 for laboratory sampling in case of absence of clinical signs.
4.1.1.6 (Scenario 7) For non‐affected establishments located in a protection zone with a radius larger than 3 km. It might not always be feasible to visit all the establishments in the protection zone in a reasonable time to detect the disease as soon as possible.
Based on kernels estimations (see also Section 4.3.1) the probability of LSD transmission from an infected establishment beyond the borders of a protection zone of 20 km is 0.3% (Israel Kernel) and 0.2% (Albania Kernel).
The probability of an infection occurring within the 4.5 km radius zone from an infected establishment is higher than 95% while the probability of the disease escaping from this area is 0.05%.
When assuming a low design prevalence of animals with clinical signs of 1%, in establishments up to 300 animals all the animals should be subjected to clinical examination. All the establishments within the protection zone should be visited, provided that it is feasible for the veterinary authorities to early detect the disease in a reasonable time.
In case it is not feasible to visit all the establishments in the protection zone, the authorities should prioritise their visits to all the establishments located at a certain distance (e.g. 4.5 km or 10 km) from the affected one and then gradually extend the visits outwards to the establishments located beyond this distance up to the borders with the surveillance zone.
Visits to establishments epidemiologically linked to an affected establishment should be prioritised and samples should be collected in case a suspicion is raised following the procedures described in Section 4.1.1.1.
All the animals of the listed species in the establishments decided to be visited, should be subjected to individual clinical examination (including palpation of the skin and temperature measurement).
In some cases where the individual clinical examination of all the animals in the establishment is not feasible, the minimum sample of animals should be clinically examined with a confidence level at least 95% assuming low target (design) prevalence of the disease.
See also 1st scenario in Section 4.1.1.1 in case of LSD suspicion in the establishments.
4.1.1.7. (Scenario 8) For non‐affected establishments located in a surveillance zone. Based on kernels estimations (see also Section 4.3.1) the probability of the disease escaping the protection zone of 20 km is 0.3% (Israel Kernel) and 0.2% (Albania kernel).
Based on kernels estimations (see also Section 4.3.1) the probability of the disease escaping the surveillance zone of 50 km is less than 0.1% in both kernels (Israel and Albania) Efforts should be allocated to increase awareness in the surveillance zone instead of conducting surveillance to the establishments because the probability of LSD having escaped beyond the limits of the protection zone into the surveillance zone is very low;
Any establishment where specific or more generic signs of the disease such as fever, lethargy, lost appetite, nasal/ophthalmic/oral discharge, oedema of the limbs, lameness and even changes in the individual animal behaviour, in the feed intake and productivity, should be visited and the animals should be clinically examined and samples should be collected following the procedures described in Sections 4.1.1.1 and 4.1.1.2.
Establishments in the surveillance zone epidemiological linked to an affected establishment or to any other establishment in the protection zone should be visited, the animals should be clinically examined and samples should be collected in case a suspicion is raised following the procedures described in Section 4.1.1.1. and Section 4.1.1.2.
To grant derogations for animal movements
4.1.2.1. (Scenario 9) From non‐affected establishments located in the protection zone to slaughterhouses located within the protection zone or in the surveillance zone or outside the restricted zone. In early stages of the infection, there is a window during which the diagnostic tools (clinical examination or laboratory methods) may not be able to detect the infection. Clinical examination of all the animals in the establishment before movement. See also 1st scenario in Section 4.1.1.1.
In some cases where the individual clinical examination of all the animals in the establishment is not feasible, the minimum sample of animals should be clinically examined with a confidence level at least 95% assuming low target (design) prevalence of the disease as described in Section 4.1.1.2.
Animals should be protected against vector feeding activity in origin, destination and during transportation
In addition to clinical examination, laboratory examination of samples from the animals intended to be moved is necessary to rule out the presence of LSD, with a confidence level of 95%. The procedures of Section 4.1.1.2 for sampling in the absence of clinical signs should be followed.
If a vaccination programme is implemented, the establishment of origin should be vaccinated, all the animals to be moved should be vaccinated and the level of vaccination coverage in the area where the slaughterhouse is located should be high enough (90% farm level coverage or higher according to EFSA (2018)) to protect the spread of the LSDV. In that case, and if the slaughterhouse is located within the protection zone, there is no need for laboratory examination if there are no other reasons based on the national risk assessment to recommended it (e.g. epidemiological link with affected establishment). Clinical examination as described above would be enough. On the contrary if the slaughterhouse is located outside the protection zone, laboratory examination as described above is recommended regardless the vaccination status.
4.1.2.2 (Scenario 12) From non‐affected establishments located in the protection zone to a plant approved for processing or disposal of animal by‐products in which the animals are immediately killed. As scenario 9 in Section 4.1.2.3 See recommendation above for Section 4.1.2.1 (scenario 9)
4.1.2.3. (Scenario 13) From an establishment in a surveillance zone to a slaughterhouse located within or outside the restricted zone and from an establishment outside the surveillance zone to a slaughterhouse situated in the surveillance zone. As scenario 9 in Section 4.1.2.3
According to the assessment for the length of the radius of the protection and the surveillance zone in Section 4.3.1, the probability of LSDV having escaped beyond the limits of the protection zone (of 20 km) into the surveillance zone is very low (0.3% Israel Kernel and 0.2% Albania Kernel) while beyond the surveillance zone (of 50 km) is even less (0.1% for both kernels). Clinical Examination of all the animals in the establishment before movement as described in the 1st scenario in Section 4.1.1.1.
In some cases where the individual clinical examination of all the animals in the establishment is not feasible, the minimum sample of animals should be clinically examined with a confidence level at least 95% assuming low target (design) prevalence of the disease as described in Section 4.1.1.2.
In addition to clinical examination, laboratory examination of samples from animals intended to be moved from a non‐affected establishment located in the surveillance zone to a slaughterhouse located outside the restricted zone is necessary to rule out the presence of LSDV, with a confidence level of 95%. The procedures of Section 4.1.1.2 for sampling in the absence of clinical signs should be followed.
For animals intended to be moved from an establishment located within or outside the surveillance zone to a slaughterhouse situated in the surveillance zone, there is no need for laboratory examination, if there are no other reasons based on the national risk assessment to recommended it (e.g. epidemiological link with affected establishment or with affected or high‐risk area). Only clinical examination as described above would be enough.
Animals should be protected against vector feeding activity at the site of origin, destination and during transportation.
If a vaccination programme is implemented, the establishment of origin should be vaccinated, all the animals to be moved should be vaccinated and the level of vaccination coverage in the area where the slaughterhouse is located should be high enough (90% farm level coverage or higher according to EFSA (2018)) to protect the spread of the LSDV.
In that case and if the slaughterhouse is located outside the restricted zone, samples for laboratory examination of animals intended to be moved is recommended regardless the vaccination status. The procedures of Section 4.1.1.2 for sampling in the absence of clinical signs should be followed.
4.1.2.4. (Scenario 14) From an establishment in a surveillance zone to pastures situated within the surveillance zone. As scenario 9 in Section 4.1.2.3 Clinical Examination of all the animals in the establishment before movement as described in the 1st scenario in Section 4.1.1.1.
In some cases where the individual clinical examination of all the animals in the establishment is not feasible, the minimum sample of animals should be clinically examined with a confidence level at least 95% assuming low target (design) prevalence of the disease as described in Section 4.1.1.2.
Animals should be protected against vector feeding activity at the origin, the destination and during transportation.
There is a need for increased vigilance on the part of farmers as the grazing animals are usually less supervised and the observation of clinical signs may delay.
In addition to the clinical examination, laboratory examination of samples from the animals intended to be moved is necessary to rule out the presence of LSD, with a confidence level of 95%. The procedures of Section 4.1.1.2 for sampling in the absence of clinical signs should be followed.
See also 1st scenario in Section 4.1.1.1.
If a vaccination programme is implemented, the establishment of origin should be vaccinated, all the animals to be moved should be vaccinated and the level of vaccination coverage in the area where pastures are located should be high enough (90% farm level coverage or higher according to EFSA (2018)) to prevent the spread of the LSDV. In that case, there is no need for laboratory examination if there are no other reasons based on the national risk assessment to recommended it (e.g. epidemiological link with affected establishment or with affected or high‐risk area). Clinical examination as described above would be enough.
4.1.2.5. (Scenario 15) From an establishment in a surveillance zone to an establishment belonging to the same supply chain, located in or outside the surveillance zone. As scenario 9 in Section 4.1.2.3 Clinical Examination of all the animals in the establishment before movement as described in the 1st scenario in Section 4.1.1.1.
In some cases, where the individual clinical examination of all the animals in the establishment is not feasible, the minimum sample of animals should be clinically examined with a confidence level at least 95% assuming low target (design) prevalence of the disease as described in Section 4.1.1.2.
Animals should be protected against vector feeding activity at the site of origin, destination and during transportation.
If animals are kept in stables, control of breeding sites and larval population of vectors is recommended.
In addition to the clinical examination, laboratory examination of samples from the animals intended to be moved is necessary to rule out the presence of LSD, with a confidence level of 95%. The procedures of Section 4.1.1.2 for sampling in the absence of clinical signs should be followed.
If a vaccination programme is implemented, the establishment of origin should be vaccinated, all the animals to be moved should be vaccinated and the level of vaccination coverage in the area where the establishment of destination is located should be high enough (90% farm level coverage or higher according to EFSA (2018)) to prevent the spread of the LSDV. In that case, and if the establishment of destination is located within the surveillance zone, there is no need for laboratory examination if there are no other reasons based on the national risk assessment to recommended it (e.g. epidemiological link with affected establishment or with affected or high‐risk area). Clinical examination as described above would be enough. On the contrary if the establishment of destination is located outside the surveillance zone, laboratory examination as described above would be recommended regardless the vaccination status.
4.2.1.6 (Scenario 18) From an establishment located in the restricted zone to move within the restricted zone when restriction measures are maintained beyond the period set out in Annex XI of the Delegated Regulation. Scenarios 9, 12,13,14 and 15, of Sections 4.1.2.1, 4.1.2.2, 4.1.2.3, 4.1.2.4 and 4.1.2.5, respectively. The recommendations of the scenarios 9, 12,13,14 and 15 of Sections 4.1.2.1, 4.1.2.2, 4.1.2.3, 4.1.2.4 and 4.1.2.5 should be implemented accordingly.
For repopulation purposes
4.1.3.1 (Scenario 19) For the animals that are kept for the repopulation prior to their introduction. Animals intended to repopulate previously affected establishments should originate from free areas outside the restricted zones of LSD to avoid re‐introduction of the disease in the establishment of destination. During the repopulation the role of vectors to the transmission of the disease should be taken into consideration. Clinical examination of all the animals in the establishment before movement as described in the 1st scenario in Section 4.1.1.1.
In some cases where the individual clinical examination of all the animals in the establishment is not feasible, the minimum sample of animals should be clinically examined with a confidence level at least 95% assuming low target (design) prevalence of the disease as described in Section 4.1.1.2.
In addition to the clinical examination, laboratory examination of samples from the animals intended to be moved is necessary to rule out the presence of LSDV with a confidence at least of 95%. The procedures of Section 4.1.1.2 for sampling in the absence of clinical signs should be followed. In case the animals are originated from establishments located in free areas, there is no need for laboratory examination if there are no other reasons based on the authorities’ risk assessment to recommend it (e.g. epidemiological link with an affected establishment or with an affected or high‐risk area). Clinical examination as described above would be enough.
The transport of animals is better to avoid season and/or hours of high activity of the vectors with highly abundance in the area, where the transmission is taken place.
Animals should be protected against vector feeding activity at sites of origin, destination and during transportation and a vector control programme is recommended to be in place in the establishment.
In case a vaccination programme is implemented, all the animals that are kept for repopulation should be vaccinated and the level of vaccination coverage, in the area where the establishment of the repopulation is located, should be high enough (90% farm level coverage or higher according to EFSA (2018)) to prevent the spread of the LSDV.
4.1.3.2 (Scenario 20) In the event of unusual mortalities or clinical signs being notified during the repopulation. During the repopulation of an establishment previously affected by LSD, there is still a risk of re‐introduction of the disease with the new animals being infected either at the establishment of origin or during their transport and a risk of re‐emergence of the disease if the new animals are infected after their arrival at the establishment of destination. In that case, the role of the relevant vectors the possibility of LSDV overwintering should be considered. The repopulation should be stopped and the procedures for the laboratory confirmation that are described in Section 4.1.1.1 in case of suspicion, should be followed.
The establishments from where the suspected animals origin, should be considered as suspects. The procedures that are described in Section 4.1.1.1 should be followed as well to the establishments of origin.
Animals should be protected against vector feeding activity in the sites of origin, destination and during transportation.
The repopulation is better to take place during the season of the year, where the abundance and the activity of the relevant vectors is low.
In case a vaccination programme is implemented, all the animals that are indented for repopulation should be vaccinated and, the level of vaccination coverage, in the area where the establishment of the repopulation is located should be high enough (90% farm level coverage or higher according to EFSA (2018)) to prevent the spread of the LSDV.
4.1.3.3 (Scenario 21) For animals that have been repopulated. During the repopulation of an establishment previously affected by LSD, there is still a risk of re‐introduction of the disease with the new animals being infected either at the establishment of origin or during their transport and a risk of re‐emergence of the disease, if the new animals are infected after their arrival at the establishment of destination. In that case, the role of the relevant vectors the possibility of LSDV overwintering should be considered. The last day of the monitoring period following the latest day of animals’ introduction, all the animals should be subjected to thorough clinical examination (skin palpation and temperature measurement included) as described in Section 4.1.1.1.
In some cases where the individual clinical examination of all the animals in the establishment is not feasible, the minimum sample of animals should be clinically examined with a confidence level at least 95% assuming low target (design) prevalence of the disease as described in Section 4.1.1.2.
To rule out the presence of LSD in the animals intended to be moved, with confidence level of 95% through laboratory examinations, the procedures of Section 4.1.1.2 for sampling in the absence of clinical signs should be followed.
In addition, the establishments from where the suspected or confirmed animals coming from, should be considered as suspects. The procedures that are described in Section 4.1.1.1 should be followed as well to the establishments of origin.
Animals should be protected against vector feeding activity in origin, destination and during transportation.
The repopulation is better to take place during the season of the year where the abundance and the activity of the relevant vectors is low.
In case vaccination is implemented, all the animals that are indented for repopulation should be vaccinated and the level of vaccination coverage, in the area where the establishment of the repopulation is located, should be high enough (90% farm level coverage or higher according to EFSA (2018)) to prevent the spread of the LSDV.
ToR 2
4.2 Length of the monitoring period The longest length of the period between infection and suspicion of LSD ranged from 32 to 56 days (44 days average).
The average length was 22 days, with the shortest time to suspicion being 7 days.
Scenario 5
Experimental studies show that the earliest day of seroconversion is 7 days post infection/inoculation as identified by indirect immunofluorescence test (iIFT), while the latest date of seroconversion is 28 days as identified by ELISA and also by VNT.
Consequently, sampling the animals 35 (28 + 7) days after semen collection as it is foreseen in the Delegated Regulation is considered effective to detect antibodies with several laboratory methods, given that the infection was occurred the latest at the day of semen collection.
Scenarios 6 and 7
Assuming that the latest point of infection of the cattle introduced into the repopulated establishment is the day when the animals are moved, and considering that the average length of time to detection is 22 days, it would be likely that some clinical signs would be present in cattle if this visit is carried out 28 days after the last introduction of the cattle.
In this scenario, using the average length of time to detection would be justified as a high awareness will exist during the examination of the animals at the first visit. The EFSA AHAW Panel considers the existing length of the monitoring period (28 days) effective as it would allow for early detection of potentially infected cattle at the first visit following re‐stocking. Scenarios 1, 2 and 3
The length of the monitoring period of 28 days as defined in the Delegate Regulation is considered effective, except for the first affected establishments, where 44 days (average between 32 and 56 days of the longest monitoring period) is recommended.
Scenario 5
None
Scenarios 6 and 7
None
ToR 3
4.3.1 Assessment of the minimum radius The defined minimum radius of 20 km and 50 km of the protection and the surveillance zone, respectively, are considered effective to restrain the spread of LSD beyond their borders if it were to occur with 99% probability.
In addition, even shorter radiuses such as 10.3 km and 4.5 km can provide 99% and 95% probability, respectively, that the transmission will not escape beyond their limits. A reduction of the minimum radius of the protection and the surveillance zone may be considered. If so, as the kernels used for the assessment of the radius referred to countries outside the EU (Israel and Albania, as vaccination was used in Greece and Bulgaria), a cautious approach of a protection zone of 10 km is recommended (the probability of transmission outside the protection zone being 1.1%) and of a surveillance zone of 30 km (the probability of transmission outside the surveillance zone being 0.1%). If/when further data becomes available, the size of the radius should be reviewed accordingly.
4.3.2 Assessment of the minimum period Based on the results of the ELS as presented in Table 4 in Section 4.2.1 it follows that the average time between introduction and suspicion is 22 days. The maximum period between introduction and suspicion can range from 32 to 56 days with an average of 44 days. Consequently, the minimum period of 45 days indicated in the Delegated Regulation for the restriction measures is considered effective to detect infected establishments and to prevent the movement of infected animals from the surveillance zone. None