ASF early detec-on diagnosis and control. Vi4orio Guber- ISPRA, Italy

Transcription

1 ASF early detec-on diagnosis and control Vi4orio Guber- ISPRA, Italy

2 Early Detec-on System (OIE) ü A system for the -mely detec-on and iden-fica-on of an incursion or emergence of diseases/infec-ons in a country, zone or compartment. It includes 1. Representa-ve coverage of target animal popula-ons by field services; 2. Ability to undertake effec-ve disease inves-ga-on and repor-ng; 3. Access to laboratories capable of diagnosing and differen-a-ng relevant diseases; 4. Training programme for veterinarians veterinary para-professionals, livestock owners/keepers and others involved in handling animals for detec-ng and repor-ng unusual animal health problems; 5. the legal obliga-on of private veterinarians to report to the Veterinary Authority; 6. A na-onal chain command.

3 Passive (reac-ve) Ac-ve (proac-ve) Animals that belong to the Suspect case defini0on are tested Animal owners report a suspect case to the Vets The suspect case defini-on drives the whole detec-on system The Veterinarians directly collect animal health data using a defined protocol A popula-on or a part of it (risk based) is ac-vely inves-gated to detect an infec-on Vets, go in the farm and take samples, check the animals

4 PASSIVE OR ACTIVE: WHICH IS BETTER? Passive works be4er when An official suspect case defini-on is available and well known among stakeholders Diseases causing evident clinical symptoms with high lethality rate There is high animal owners and Veterinary Service awareness Ac-ve works be4er when Clinical symptoms of the disease are not evident, episodic or short las-ng Low/null lethality rate Low animal owners awareness

5 ASF early detec-on in domes-c pigs PASSIVE SURVEILLANCE The most effective tool for detecting ASF [Evident clinical signs, High lethality ( %)]. Due to the clinical similarity with other diseases (e.g. CSF) passive clinical surveillance always needs to be confirmed by laboratory In Commercial holdings Ø Strict health monitoring programme of pig holdings Reporting of dead and sick animals Ø Reporting any decreasing of production parameters In Backyard holdings Ø Repor(ng of sick or dead animals Ø Vet inspec(on on pig slaughtering for own consump(on (pigs with lesions/symptoms examined and tested)

6 Passive Surveillance ü Covers wide areas / en-re country ü Covers the en-re popula-on ü Every day of the year ü Can provide -mely informa-on ü Is cost efficient if implemented properly 6

7 Passive Surveillance PIG OWNERS and PRACTITIONNAIRS have to report suspected cases ü Ac-on to report can only be encouraged by veterinary services ü Implementa-on is not under the Vet Service control ü Dependence on stakeholder ü Requires a sense of responsibility by the farmer

8 The detec-on strategies of ASF might vary in different regions of the world The EARLY DETECTION STRATEGY needs to be tailored to the epidemiological situa-on and take into account: The risk of ASF introduc-on Prevalent type of pig produc-on system Presence of wild and feral pigs Presence of different species of SUIDAE Presence of Ornithodoros -cks ASFV genotype Free status Early Detec-on Eradication/Endemicity 8

9 Early detec-on probability and disease control efficency Increased when available: Risk Analysis ü We know where and when to expect problems / where and what to look for Con0ngency Planning ü We know how we would react once we find it Training / Awareness ü Everybody that needs to know about it, is informed and knows what to do

10 ASF early detection: main categories at risk IF the risk analysis assesses an increased likelihood of infec(on in par(cular locali(es or subpopula(ons exists, targeted surveillance could be appropriate. This may include: Specific high-risk wild boar populations Pigs reared outdoors Farms which feed swill Areas in which the disease has been previously detected or bordering already infected areas Evidence of involvement of ticks

11 Early detec0on of ASF in wild boars Passive surveillance vs. ac0ve surveillance LATVIA: Summary of wild boar data (June-December, 2014) within the infected area Number of tested animals Number of posi-ve results WB found dead WB hunted

12 EFFICACY OF PASSIVE VS ACTIVE SURVEILLANCE: FIELD DATA VIRUS DETECTION IN DEAD ANIMALS: 178/227 = 78% VIRUS DETECTION IN SHOT ANIMALS: 39/2733 =1,4% DETECTION IN DEAD/DETECTION IN SHOT 0,78/0,014 = 55,7 THE PROBABILITY TO DETECTED A VIRUS IN DEAD ANIMALS IS 55 TIMES HIGHER THAN IN SHOT ANIMALS (55/(55+1)*100 = 98% 98 OUT OF 100 VIRUSES ARE LIKELY TO BE DETECTED IN DEAD WILD BOARS 12

13 Modeling ASF surveillance in wild boar Virus and an-body detec-on probability according to passive and ac-ve surveillance

14 ASF laboratory diagnosis Virus could be excreted few hours before animals show clinical signs But, in real life, animals showing clinical signs are the ones in which the laboratory detec-on of the virus has to be carried out ANIMALS SHOWING CLINICAL SIGNS including dead animals (being death one of the main clinical sign)

15 Which samples in alive animals? 3-5 ml Blood with EDTA from viremic pigs for detec-on of viral an-gens and/or viral DNA (heparin hind PCR!) Clo4ed blood (without EDTA) Oral fluid for detec-on of specific Abs NO EARLY DETECTION

16 Dead animals The most suitable matrixes are: Tonsils, lymph nodes, spleen, kidney, lungs; In case of autolysed carcasses bone marrow from long bone or sternum; Take care on blood high risk of ASF spreading!

17 TEST Isola-on and iden-fica-on (HAD) WHAT WE ARE DETECTING? Alive virus An0gen ELISA Immunofluorescence (DIF) Chromatography (pen-side test) direct Viral an-gen ELISA IB IPT IIF PCR Sequencing indirect An-bodies Gene-c material (DNA) Nucleo-des sequence in analysed gene

18 PCR: the most frequently used technique rapid, high sensi-vity and specificity, useful for tes-ng of different matrices, including old and autoly-c samples (old wild boar bone marrow) required equipped lab. and skilled staff, Sensi-vity: contamina-on of the lab with DNA = false (+) results, Specificity: improper primers = false (-) results (different genotypes) large-scale test.

19 Serology: commercial ELISA but posi0ve samples have to be confirmed by IPT q Not useful for early detec0on in free areas since animals die before developing an0bodies q Useful in endemic areas only q Possibility of: Approximate es-ma-on of -me of infec-on in domes-c pigs, Monitoring of diseases spreading in wild boars; Changes in pathogenicity

20 In the field - -me from infec-on -ll detec-on 1-3 months!!! In the lab few hours Diagnosis: In 1 week cost ~ 2 mln Euro In 2 weeks cost ~22 mln Euro

21 ASF is detected!!!!! BTSF Consumers, Health And Food Execu(ve Agency

22 Key elements of outbreak management domes(c pigs Culling BTSF of infected and suspected animals Sampling of culled animals Carcasses, feed etc. destroyed Protec-on and surveillance zones Epidemiological inves-ga-on Cleaning and disinfec-on Restocking 22 Consumers, Health And Food Execu(ve Agency

23 Establishment of protec-on and surveillance zones BTSF 10 km 3 km 10 km 3 km Hypothe-cal examples of different approaches Consumers, Health And Food Execu(ve Agency

24 Establishment of protec-on and surveillance zones Various BTSF aspects must be taken into considera-on Prac-cality - delinea-on in accordance with exis-ng boundaries [takes -me, but may be easier to perform ac-vi-es] or in accordance with a map system [easier to perform, measures may prove to be harder to execute] Natural or ar-ficial boundaries (roads) Presence of slaughterhouses (welfare issues) Increasing the BIOSECURITY LEVEL (back yard pigs?) 24 Consumers, Health And Food Execu(ve Agency

25 Establishment of protec-on and surveillance zones Measures in the protec-on and surveillance zones Census BTSF Stands-ll of pigs (except for specific circumstances pigs are not allowed to move out of holdings) Ongoing clinical surveillance by official veterinarians Meat produced in the areas or from pigs origina-ng in the areas (a situa-on possible only aver mee-ng strict criteria) must be specially treated Competent authori-es enforce strict control over movements of pigs and their product (in order to 25 prevent the spread of ASF) Consumers, Health And Food Execu(ve Agency

26 Withdrawing of restric-ons Once an outbreak is established, restric-ons may only be removed BTSF if: Final cleaning & disinfec-on is performed Removal and destruc-on of slurry and manure Removal (and possibly destruc-on) of pieces of equipment Scrubbing and then degreasing of all the surfaces Applica-on of the proper disinfectant (for at least 24 h) Rinsing with water Consumers, Health And Food A wai-ng period of 40 Execu(ve days Agency must elapse 26

27 Withdrawing of restric-ons The final step: restocking with sen-nel pigs BTSF Those pigs must be tested for ASF (serology) with nega-ve results and be kept for 45 days in the holding Then they must be retested If all the results are nega-ve then complete restocking may take place 27 Consumers, Health And Food Execu(ve Agency

28 The problem of having ASF in wild boar According to the EU legisla-on the size of the infected wild boar popula-on area will be at least 200 sqkm The wild boar infected area will enforced for at least 24 months In the area the domes-c pig popula-on is under restric-on (stand s-ll, biosecurity, surveillance etc.) and goes immediately out of the market

29 Control strategy in wild boar Outside Infected area: => intensive hun-ng (including economic incen-ves) Buffer: yearly wild boar home range Infected area: outside core area Targeted hun-ng of adult females Hun-ng under biosecurity procedures All shot animals rendered (not home taking) Buffer Core area defined by passive surveillance (dead infected wild boar) Core and buffer area: ban of hun-ng, Forbidden entrance for general public Ac-ve search of wild boar carcasses ONLY

30 Un-l now the only area where ASF has been (apparently) eradicated in wild boar in the EU Higest risk fenced area Low risk area Intensive hun-ng area 5305 hunted wild boars at 13 October 2017 High risk area (fenced plus buffer Designed according wild boar home range

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33 Fresh meat and products from pigs Commission Implementing Decision 2014/178/EU Fresh meat and products from wild boar Live pigs Other EU- MS, Third countries Infected zone (Part III) Buffer zone (Part II) Member State (free of ASF) Live wild boar Other EU- MS, Third countries semen, ova, embryo animal by-products Allowed Prohibited DerogaFon

34 (or safe disposal) of shot animals and biosecurity Take at home message Passive surveillance is the best (sole) ASF early detec-on strategy Awareness of animal owners, stakeholders (i.e. hunters) and private veterinarians is essen-al Diagnosis is rela-vely easy and fast Serology is of limited help in early detec-on in free areas whereas it is important in outbreak inves-ga-on and in endemic areas Outbreak management in domes-c pigs is based on culling and compensa0on (no compensa-on: no disease management i.e. Caucasus) Control in wild boar popula-on is based on a set of measures including: ban of hun-ng, targeted hun-ng of adult females, rendering