Investigation of the factors that affect the spread of Lumpy Skin Disease: analysis of the epizootic in Greece

Εισαγωγή: H Οζώδης Δερματίτιδα των βοοειδών (ΟΔΒ) αποτελεί ένα λοιμώδες ιογενές νόσημα των βοοειδών με σοβαρές συνέπειες για την κτηνοτροφία και την αγροτική οικονομία λόγω των συμπτωμάτων, της μείωσης της παραγωγικότητας και τις έμμεσες απώλειες από την εφαρμογή των μέτρων ελέγχου (π.χ. θανάτωση των ζώων, περιορισμοί των εμπορικών δραστηριοτήτων σε ζώα και ζωικά προϊόντα). Εμφανίστηκε για πρώτη φορά τον Αύγουστο του 2015 στη βορειοανατολική Ελλάδα, στην Περιφερειακή Ενότητα Έβρου κοντά στα σύνορα με την Τουρκία. Το νόσημα μέχρι το τέλος του 2016, εξαπλώθηκε αρχικά δυτικά και στη συνέχεια νότια, ενώ το 2017 επιβεβαιώθηκαν μόνο δύο σποραδικές εστίες. Επείγων εμβολιασμός, με ομόλογα ελαττωμένης λοιμογόνου δύναμης ζωντανά εμβόλια, εφαρμόστηκε επιπρόσθετα των λοιπών μέτρων ελέγχου. Σκοπός: Σκοπός της μελέτης είναι η διερεύνηση της επίδρασης ορισμένων παραγόντων στην επιζωοτία της Οζώδους Δερματίτιδας στην Ελλάδα: i)το μέγεθος της εκτροφής, ii) την παραγωγική κατεύθυνση της εκτροφής, iii) το σύστημα ενσταβλισμού, iv)το εμβολιαστικό καθεστώς, v) την εγγύτητα από μια μολυσμένη εκτροφή, vi) τη θερμοκρασία περιβάλλοντος, vii) την εποχή του έτους και viii) την Περιφέρεια στην οποία βρίσκεται μια εκτροφή. Μέθοδος: Πρόκειται για μια αναδρομική μελέτη που βασίζεται σε μοντέλο λογιστικής παλινδρόμησης με ατομικές παρατηρήσεις σε επίπεδο εκτροφής. Συμπεριλήφθηκαν 8,365 farms εκ των οποίων οι 290 (3.47%) μολύνθηκαν ενώ οι υπόλοιπες 8,075 (96.53 %) δεν είχαν μολυνθεί μέχρι το τέλος της περιόδου μελέτης. Η μελέτη περιλαμβάνει τις εκτροφές που βρίσκονται στη βόρειο Ελλάδα στις Περιφέρειες Ανατολικής Μακεδονίας και Θράκης, Κεντρικής Μακεδονίας και Δυτικής Μακεδονίας. Η χρονική περίοδος της μελέτης συμπίπτει με την διάρκεια της επιζωοτίας στην περιοχή. Αποτελέσματα: Η μελέτη εντόπισε ότι πέντε από τους παράγοντες που εξετάστηκαν είχαν στατιστικά σημαντική επίδραση στην έκβαση του νοσήματος (μολυσμένη, μη-μολυσμένη εκτροφή) σε επίπεδο στατιστικής σημαντικότητας 5%, όταν σταθμίστηκαν για όλους τους άλλους παράγοντες. Ο εμβολιασμός έχει ισχυρή επίδραση στην έκβαση της ΟΔΒ: εμβολιασμένες φάρμες έχουν O.R.=0.053 (95% C.I.: 0.013 to 0.218) σε σχέση με τις μη εμβολιασμένες. Εκτροφές με σύστημα ενσταβλισμού που επιτρέπει την ελεύθερη βόσκηση, έχουν O.R.= 3.953 (95% C.I. 2.855 - 5.476) σε σχέση με τις σταβλισμένες. Η απόσταση από την πλησιέστερη μολυσμένη εκτροφή έχει O.R.= 0.766 (95% C.I. 0.735 - 0.8) ανά μονάδα απόστασης (χιλιόμετρο). Ο αριθμός των ζώων στην εκτροφή έχει O.R.= 1.002 (95% C.I. 1.001 - 1.004) ανά μονάδα (1 ζώο). Η θερμοκρασία περιβάλλοντος έχει O.R.= 1.069 (95% C.I. 1.024 - 1.115) ανά μονάδα (βαθμός Κελσίου). Το καλοκαίρι έχει O.R = 5.38 (95% C.I. 2.501 - 11.570) σε σχέση με την άνοιξη. Οι εκτροφές που βρίσκονται στην Περιφέρεια της Κεντρικής Μακεδονίας έχουν O.R = 5.753 (95% C.I. 3.105 - 10.658) σε σχέση με αυτές που βρίσκονται στην Ανατολική Μακεδονία και Θράκη. Η μελέτη έδειξε ότι ο τύπος της παραγωγικής κατεύθυνσης της εκτροφής (γαλακτοπαραγωγής, κρεοπαραγωγής, μεικτή) δεν παρουσιάζει στατιστικά σημαντική επίδραση στην έκβαση του νοσήματος. Συμπεράσματα: Η μελέτη δείχνει ότι ο εμβολιασμός μειώνει την πιθανότητα μόλυνσης μιας εκτροφής κατά 94% και γι΄ αυτό μπορεί να είναι ένα αποτελεσματικό μετρό κατά της νόσου. Οι εκτροφές με σύστημα ενσταβλισμού που επιτρέπει την ελεύθερη βόσκηση είναι πιο πιθανό να μολυνθούν. Καθώς η απόσταση μιας εκτροφής από μια άλλη μολυσμένη εκτροφή μεγαλώνει, είναι λιγότερο πιθανό να μολυνθεί. Η αύξηση της θερμοκρασίας περιβάλλοντος παρά η εποχή του χρόνου φαίνεται να αυξάνει την πιθανότητα μόλυνσης μιας εκτροφής. Τα παραπάνω αποτελέσματα μπορεί να είναι χρήσιμα στις Κτηνιατρικές Αρχές στην εφαρμογή αποτελεσματικών μέτρων ελέγχου και στην οργάνωση των εκστρατειών εμβολιασμού.Introduction: Lumpy Skin Disease (LSD) is an infectious viral disease of cattle and buffalos, with serious impact on livestock and rural economy due to the symptoms, the reduction of productivity and the indirect loses caused by the implementation of the control measures (e.g. stamping out policy, restrictions to the trade activities of animals and animal products). LSD emerged in August 2015, for the first time, in the northeast part of Greece, in the Regional Unit of Evros, close to the borders with Turkey. The disease, up until the end of 2016, spread initially westwards and subsequently moved southwards, while in 2017 only two sporadic outbreaks were confirmed. Emergency vaccination, with homologous live attenuated virus vaccines, implemented in addition to other control measures in order to halt the spread of the disease. Objectives: The objective of this study is to investigate the effect of some factors on LSD epizootic in Greece: i) the size of the farm, ii) the production activity, iii) the housing system, iv) the status of vaccination, v) the proximity of an infected farm, vi) the ambient temperature, vii) the season of the year and viii) the region of the location. Methods: It is a retrospective study based on logistic regression model with individual observations at farm level. They were included 8,365 farms from which 290 (3.47%) got infected and 8,075 (96.53 %) were non infected at the end of the study period. The study concerns the farms located in the north part of Greece, in regions of East Macedonia and Thrace, West Macedonia and Central Macedonia. The time period of the study coincides with the period of the LSD epizootic in the area of the study. Results: This study identified that five of the assessed factors have a statistically significant effect, at the level of 5% on the outcome of the disease (infected, non-infected), when adjusted for all the other factors. The vaccinated farms have an O.R.=0.053 (95% C.I.: 0.013 to 0.218) compared to non-vaccinated. The farms with outdoor housing system have an O.R.= 3.953 (95% C.I. 2.855 to 5.476) compared to indoor farms. The distance from the closest infected farm has an O.R.= 0.766 (95% C.I. 0.735 to 0.8) per unit (kilometer). The number of animals in the farm has an O.R.= 1.002 (95% C.I. 1.001 to 1.004) per unit (1 animal). The ambient temperature has an O.R.= 1.069 (95% C.I. 1.024 to 1.115) per unit (Celsius degree). The summer has an O.R =5.38 (95% C.I. 2.501 to 11.570) compared to spring. The farms located in region of Central Macedonia have an O.R = 5.753 (95% C.I. 3.105 to 10.658) compared to those in East Macedonia and Thrace. The study showed that the type of production of the farm (beef, dairy, mixed) does not have a statistically significant effect on the outcome of the disease. Conclusions: The study shows that the vaccination decreases the likelihood of a farm to get infected by 94.7 % and thus can be an effective measure against the disease. The outdoor farms are more likely to get infected compared to indoors. As the distance from an infected increase, it is less likely for a farm to get infected. The increase of the temperature rather than the season of the year seams to increase the likelihood of infection. These results may be useful to the Veterinary Authorities, in order to implement effective control measures and to organize their vaccination campaigns

Research gap analysis on African swine fever

The most significant knowledge gaps in the prevention and control of African swine fever (ASF) were identified by the EU Veterinary services and other stakeholders involved in pig production and wild boar management through an online survey. The respondents were asked to identify the major research needs in order to improve short-term ASF risk management. Four major gaps were identified: ‘wild boar’, ‘African swine fever virus (ASFV) survival and transmission’, ‘biosecurity’ and ‘surveillance’. In particular, the respondents stressed the need for better knowledge on wild boar management and surveillance, and improved knowledge on the possible mechanism for spread and persistence of ASF in wild boar populations. They indicated the need for research on ASFV survival and transmission from the environment, different products such as feed and feed materials, and potential arthropod vector transmission. In addition, several research topics on biosecurity were identified as significant knowledge gaps and the need to identify risk factors for ASFV entry into domestic pig holdings, to develop protocols to implement specific and appropriate biosecurity measures, and to improve the knowledge about the domestic pig–wild boar interface. Potential sources of ASFV introduction into unaffected countries need to be better understood by an in-depth analysis of the possible pathways of introduction of ASFV with the focus on food, feed, transport of live wild boars and human movements. Finally, research on communication methods to increase awareness among all players involved in the epidemiology of ASF (including truck drivers, hunters and tourists) and to increase compliance with existing control measures was also a topic mentioned by all stakeholders

African swine fever and outdoor farming of pigs

This opinion describes outdoor farming of pigs in the EU, assesses the risk of African swine fewer (ASF) introduction and spread associated with outdoor pig farms and proposes biosecurity and control measures for outdoor pig farms in ASF-affected areas of the EU. Evidence was collected from Member States (MSs) veterinary authorities, farmers’ associations, literature and legislative documents. An Expert knowledge elicitation (EKE) was carried out to group outdoor pig farms according to their risk of introduction and spread of ASF, to rank biosecurity measures regarding their effectiveness with regard to ASF and propose improvements of biosecurity for outdoor pig farming and accompanying control measures. Outdoor pig farming is common and various farm types are present throughout the EU. As there is no legislation at European level for categorising outdoor pig farms in the EU, information is limited, not harmonised and needs to be interpreted with care. The baseline risk of outdoor pig farms for ASFV introduction and its spread is high but with considerable uncertainty. The Panel is 66–90% certain that, if single solid or double fences were fully and properly implemented on all outdoor pig farms in areas of the EU where ASF is present in wild boar and in domestic pigs in indoor farms and outdoor farms (worst case scenario not considering different restriction zones or particular situations), without requiring any other outdoor-specific biosecurity measures or control measures, this would reduce the number of new ASF outbreaks occurring in these farms within a year by more than 50% compared to the baseline risk. The Panel concludes that the regular implementation of independent and objective on-farm biosecurity assessments using comprehensive standard protocols and approving outdoor pig farms on the basis of their biosecurity risk in an official system managed by competent authorities will further reduce the risk of ASF introduction and spread related to outdoor pig farms.info:eu-repo/semantics/publishedVersio

Rift Valley Fever: risk of persistence, spread and impact in Mayotte (France)

Rift Valley fever (RVF) is a vector-borne disease transmitted by different mosquito species, especially Aedes and Culex genus, to animals and humans. In November 2018, RVF re-emerged in Mayotte (France) after 11 years. Up to the end of October 2019, 126 outbreaks in animals and 143 human cases were reported. RVF mortality was 0.01%, and the number of abortions reported in polymerase chain reaction (PCR)-positive ruminants was fivefold greater than the previous 7 years. Milk loss production in 2019 compared to 2015–2018 was estimated to be 18%, corresponding to an economic loss of around €191,000 in all of Mayotte. The tropical climate in Mayotte provides conditions for the presence of mosquitoes during the whole year, and illegal introductions of animals represent a continuous risk of (re) introduction of RVF. The probability of RVF virus (RVFV) persisting in Mayotte for 5 or more years was estimated to be < 10% but could be much lower if vertical transmission in vectors does not occur. Persistence of RVF by vertical transmission in Mayotte and R eunion appears to be of minor relevance compared to other pathways of re-introduction (i.e. animal movement). However, there is a high uncertainty since there is limited information about the vertical transmission of some of the major species of vectors of RVFV in Mayotte and R eunion. The only identified pathways for the risk of spread of RVF from Mayotte to other countries were by infected vectors transported in airplanes or by wind currents. For the former, the risk of introduction of RVF to continental France was estimated to 4 9 10 6 epidemic per year 1 in 1400 years (median value; 95% CI: 2 9 10 8; 0.0007), and 0.001 epidemic per year to R eunion (95% CI: 4 9 10 6; 0.16). For the latter pathway, mosquitoes dispersing on the wind from Mayotte between January and April 2019 could have reached the Comoros Islands, Madagascar, Mozambique and, possibly, Tanzania. However, these countries are already endemic for RVF, and an incursion of RVFV-infected mosquitoes would have negligible impact.info:eu-repo/semantics/publishedVersio

Rift Valley Fever – assessment of effectiveness of surveillance and control measures in the EU

Effectiveness of surveillance and control measures against Rift Valley Fever (RVF) in Mayotte (overseas France) and in continental EU were assessed using mathematical models. Surveillance for early detection of RVF virus circulation implies very low design prevalence values and thus sampling a high number of animals, so feasibility issues may rise. Passive surveillance based on notified abortions in ruminants is key for early warning and at present the only feasible surveillance option. The assessment of vaccination and culling against RVF in Mayotte suggests that vaccination is more effective when quickly implemented throughout the population, e.g. at a rate of 200 or 2,000 animals vaccinated per day. Test and cull is not an option for RVF control in Mayotte given the high number of animals that would need to be tested. If the risk of RVFV introduction into the continental EU increases, ruminant establishments close to possible points of disease incursion should be included in the surveillance. An enhanced surveillance on reproductive disorders should be applied during summer in risk areas. Serosurveillance targets of 0.3% animals should be at least considered. RVF control measures possibly applied in the continental EU have been assessed in the Netherlands, as an example. Culling animals on farms within a 20 km radius of detected farms appears as the most effective measure to control RVF spread, although too many animals should be culled. Alternative measures are vaccination in a 50 km radius around detection, ring vaccination between 20 and 50 km and culling of detected farms. The assessment of zoning showed that, following RVFV introduction and considering an R0 = 2, a mean vector dispersal of 10 km and 10 farms initially detected, RVFV would spread beyond a radius of up to 100 km or 50 km from the infected area with 10% or 55% probability, respectively.info:eu-repo/semantics/publishedVersio

Scientific Opinion on the assessment of the control measures of the category A diseases of Animal Health Law: Highly Pathogenic Avian Influenza

EFSA received a mandate from the European Commission to assess the effectiveness of some of the control measures against diseases included in the Category A list according to Regulation (EU) 2016/429 on transmissible animal diseases (‘Animal Health Law’). This opinion belongs to a series of opinions where these control measures will be assessed, with this opinion covering the assessment of control measures for Highly Pathogenic Avian Influenza (HPAI). In this opinion, EFSA and the AHAW Panel of experts review the effectiveness of: (i) clinical and laboratory sampling procedures, (ii) monitoring period and (iii) the minimum radius of the protection and surveillance zone, and the minimum length of time the measures should be applied in these zones. The general methodology used for this series of opinions has been published elsewhere; nonetheless, specific details of the model used for the assessment of the laboratory sampling procedures for HPAI are presented here. Here, also, the transmission kernels used for the assessment of the minimum radius of the protection and surveillance zones are shown. Several scenarios for which these control measures had to be assessed were designed and agreed prior to the start of the assessment. In summary, sampling procedures as described in the diagnostic manual for HPAI were considered efficient for gallinaceous poultry, whereas additional sampling is advised for Anseriformes. The monitoring period was assessed as effective, and it was demonstrated that the surveillance zone comprises 95% of the infections from an affected establishment. Recommendations provided for each of the scenarios assessed aim to support the European Commission in the drafting of further pieces of legislation, as well as for plausible ad hoc requests in relation to HPAI.info:eu-repo/semantics/publishedVersio

Assessment of the control measures of the category A diseases of Animal Health Law: Classical Swine Fever

EFSA received a mandate from the European Commission to assess the effectiveness of some of the control measures against diseases included in the Category A list according to Regulation (EU) 2016/429 on transmissible animal diseases (‘Animal Health Law’). This opinion belongs to a series of opinions where these control measures will be assessed, with this opinion covering the assessment of control measures for Classical swine fever (CSF). In this opinion, EFSA and the AHAW Panel of experts review the effectiveness of: (i) clinical and laboratory sampling procedures, (ii) monitoring period and (iii) the minimum radii of the protection and surveillance zones, and the minimum length of time the measures should be applied in these zones. The general methodology used for this series of opinions has been published elsewhere; nonetheless, details of the model used for answering these questions are presented in this opinion as well as the transmission kernels used for the assessment of the minimum radius of the protection and surveillance zones. Several scenarios for which these control measures had to be assessed were designed and agreed prior to the start of the assessment. Here, several recommendations are given on how to increase the effectiveness of some of the sampling procedures. Based on the average length of the period between virus introduction and the reporting of a CSF suspicion, the monitoring period was assessed as non-effective. In a similar way, it was recommended that the length of the measures in the protection and surveillance zones were increased from 15 to 25 days in the protection zone and from 30 to 40 days in the surveillance zone. Finally, the analysis of existing Kernels for CSF suggested that the radius of the protection and the surveillance zones comprise 99% of the infections from an affected establishment if transmission occurred. Recommendations provided for each of the scenarios assessed aim to support the European Commission in the drafting of further pieces of legislation, as well as for plausible ad hoc requests in relation to CSF.info:eu-repo/semantics/publishedVersio