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Prof Trevor W Drew OBE Director, Australian Animal Health Laboratory Geelong, AustraliaVisiting Professor, Jilin University, PR ChinaGuest Professor, University of Nottingham, UKGF-TADS SGE-ASF-ASIA, JULY-AUG 2019
Biosecurity & Border control: Where the virus can be found - What to look for - What to test
“there is little doubt ASF will continue its geographic expansion…” (FAO EMPRES, 2012)
• Potential for serious impact on global trade and food security
• Pork considered a priority protein source for meeting future global dietary needs
• Significant investment area for small holder subsistence farmers (‘backyard sector’) in the developing world
• Food security = regional stability
• Major world players are committed to ongoing research to solve the problem
ASF: a global threat
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Implications for the region are significant
Robinson (2014)
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Definition of contagiousness
percentage of animals which get infected after contact with an infectious agent.
i.e. the probability that an animal picks up an infection after contact with a pathogen
Dependent on whether transmission is directly via an infected animal by the parenteral route, or via ingesting infected meat
How contagious is ASF?
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(30%)
Thanks to Klaus Depner, FLI, Germany
ASF Contagiousness
Within a group (within a pig barn)
Requires high virus dose (>1000
HAU) for parenteral transmission
between groups (open system…e.g. forest)
Requires low virus dose (<100 HAU) for oral transmission
HIGH
LOW
How contagious is ASF?
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Thanks to Klaus Depner, FLI, Germany
ASF virus is a relatively stable virus
ASFV survives the process of
putrefaction and carcasses
may remain infectious for weeks –
longer in cold climates
ASFV therefore presents a high
risk to free countries
• frozen meat: indefinitely
• dry meat and fat: almost one year
• blood, salted meat and offal: more than 3 months
• faeces: over one week
Temperature plays an important role in decreasing the survival
duration of ASF virus in any matrix.
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Thanks to Klaus Depner, FLI, Germany
Two main elements:
a) Preventing the virus from entering the country
• Pre-border activities
• Activities at the border
• Illegal/incidental breaches
b) Preventing the virus from infecting a pig• Farm biosecurity
• Including activities of the veterinary authority
• Wild & feral pigs
• Behaviours – all sectors
In BOTH cases, identifying risk pathways and employing robust mitigation steps are key
Keeping your country free
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Risk factors for spread of ASFDirect
• Infected domestic pigs
– Live cover
• Wild boar, carcases, abortions
• Pig products (swill feeding, spray-dried blood)
• Shared needles for vaccination, non-licensed preparations (eg autogenous vaccines)
• Germplasm, semen(?)
Indirect• Infected pens
• Contaminated feed, water
• Transport - lorries
• Personnel, veterinary visits
– Clothing, boots, instruments
– Part-used vaccines
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Ticks ???
Unlikely
Greatest risk
Illegal movement of pigs => legal movement of pigs
Illegal import of pig products => legal imports
Accidental introduction <=> accidental release
• Carcases in rivers, wild boar migration, release from laboratories
Solution:
• Follow OIE Code for legal imports
• Prevent illegal introduction of animals and products
• Identify and mitigate risks of accidental introduction or release
Preventing the virus from entering the country
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ASF is mainly introduced by HUMANS!
Pigs and products - OIE Code Chapter 15.1
• ONLY canned meat and gelatine are considered “safe” commodities• Specified conditions for heat inactivation – F0 of =>3 (3’ @ 121°C equivalent)
• ALL other commodities should follow the guidelines for import • 25 Clauses provide details
• Dependent on commodity
• Consider source country status
• Whether from domestic, or wild & feral pigs
• Involve quarantine and testing
Key issues in preventing introduction (1)
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• Movement of wild and feral pigs from infected countries• Metapopulations – move around
• Natural barriers may prevent movement
• Hunting with dogs can drive wild & feral pigs to new areas
• Good communication with neighbouring countries is key
• “Amber” response when risk is considered greater?
• Increased passive surveillance
• Testing for exclusion
• Establishment of a Protection Zone
• High risk area – eg adjacent to an infected country
• Different rules – eg no pigs allowed to be kept, or no commercial piggeries
• Increased clinical surveillance
• Removal of wild boar from the area?
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Key issues in preventing introduction (2)
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Key issues in preventing introduction (3)
• Prevent passengers from bringing meat products into your country
• Also for other diseases
• Clear messaging
• Random/targeted inspections
• Fines/other punishment – more messaging
• Random testing of seized products can help to inform assessment of risk
• Useful for persuading government of the need for change in protocols
• Can generate additional publicity
Preventing infection of your wild & feral pigs:
• Access to infected waste food
• Travel across borders to an infected country
• Contact with wild boar from an infected country
• Hunters sometimes like to “supplement” local populations• Illegally bringing in wild boar
• Supplementary feeding during winter months
Encourage reporting of “found dead” wild & feral pigs• Engage with hunters
• They can play an important role in surveillance
• Inform them of the risks
• Test dead animals and remove the carcases
Key issues in preventing infection (1)
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Preventing infection of domestic pigs:
• Swill feeding
• Difficult to prevent in backyard systems
• MUST be boiled – 30 min minimum
• Scavenging - discourage
• Food dumps
• Roadside/village scavenging
• Disposal of airline waste & seized products
• Germplasm from overseas (unless it follows OIE Code)
• Semen should be regarded as a source of infection, though evidence is scant
• Imported feed – especially those containing “growth additives”
• Unlicensed vaccines/autogenous vaccines
Good husbandry – quarantine/all-in:all-out, disinfection; restricted access
THESE MEASURES ARE UNLIKELY TO BE ACHIEVEABLE IN VILLAGE SYSTEMS
Key issues in preventing infection (2)
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• Pigs in pens• Not allowed to roam/scavenge/mingle with pigs from other premises
• Pens with solid walls are best
• Replacement stock – trusted sources, healthy. AVOID live cover!
• Fencing• Pig-proof outer boundary – some distance from pens
• Visitors/workers• Essential only. Disinfectant foot dips. Dedicated clothing.
• Workers should NOT keep pigs or work on multiple farms.
• Veterinarians should wear disposable PPE and disinfect between visits
• Equipment• Don’t share, or disinfect thoroughly
• Waste – feed, urine, faeces and dead piglets• Avoid access of wild boar or other pigs. Rivers are good at spreading ASF!
Farm biosecurity
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• Behaviours can be the biggest threat
• Insufficient resources for authorities - priorities
• especially surge capacity
• Poor knowledge can greatly aid its spread
• how the disease is transmitted
• What products may pose a hazard and how they may be made safe
• What steps are critical to preventing further spread
Reasons for active non-compliance are many
– Financial
• Desire to make profit or avoid loss
• Poor resources
– Cultural
• Traditional gifting/festivals
• Bad luck, fear of consequence
• Habitual?!
Behavioural traits – authorities and farmers
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• What are the illegal trading routes in the region?
• Routes the same – products and direction may change
• Is outbreak driving attempts to smuggle?• Even more likely with changing meat prices
• Meat from pigs in infected premises???
Behavioural traits – pigs and pork
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• Live animals don’t need refrigeration – only
water• Greater transmission risk than meat!
• Travellers – MUST change their behaviours• Total irresponsibility – but why? How do we change
behaviours?
• Penalties for non-compliance – how do we reward good
behaviour?
• Something for the SGE? A survey?
How to test? What to test?
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• Detect the virus by PCR – validated & accredited• Serology is of little, if any value
• almost all pigs are dead before they seroconvert!
• At your border/in quarantine• Imported pigs – all?
• Semen (random sampling)
• Whole carcases – random sampling
• Other testing (eg seizures) may inform risk and identify need for additional measures
• Testing of imported cut meat or meat product is generally ineffective,
• Is the sample representative?
• Is the batch homogeneous?
• A negative result doesn’t mean the whole container or batch is safe
• But is of value if it gives a positive result!
Take-home messages - epi & control
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• ASF is spread mainly spread by people via infected pigs and meat/products
• BEHAVIOURS of travellers
• Pig movements, live boar cover
• Waste food - swill feeding (spray-dried blood in the past)
• Fomites – lorries, vets, visitors,
• Passive surveillance (testing dead animals) is best/only strategy for early detection of ASF
• Awareness of animal owners, hunters, rangers, private vets is ESSENTIAL
• Outbreak management is culling & compensation
• Control in wild boar is reliant on their management• Culling adult females, carcase collection and disposal
• In countries with severe winters, may be a real challenge
• Lab diagnosis of suspect disease, by virus detection, is relatively easy, fast and reliable• But samples MUST be submitted!
• PCR is very specific & reliable
• Validated method – accredited lab and test?
• Serology is of limited help – of value mainly in demonstrating freedom
• MUST NOT wait for high mortalities
• Laboratory MUST be biosecure
• BSL2 minimum – ideally BSL3
• Lab workers should NOT keep pigs!
Take-home messages – lab testing for ASF
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Trevor W. Drew
Director. CSIRO-AAHL, Geelong, AUSTRALIA
CSIRO AUSTRALIAN ANIMAL HEALTH LABORATORY
Thank you
For more information on ASF research or diagnosis, please contact:
David Williams
Group Leader – Emergency Disease Laboratory Diagnosis
Diagnosis, Surveillance & Response unit
t +61 3 5227 5364e d.williams@csiro.auw www.csiro.au/places/aahl.html
With acknowledgements to Klaus Depner, FLI, Germany
AAHL plays a key role in assuring Australia’s biosecurityAn advanced BSL4 high containment laboratory
OIE Collaborating Centre for:
- Laboratory Capacity Building
- New & Emerging Diseases
- Diagnostic Test Validation Science in the Asia-Pacific Region
Latest official ASF situation (FAO):
http://www.fao.org/ag/againfo/programmes/en/empres/ASF/Situation_update.html
Predicted impacts on meat markets:
https://www.rabobank.com.au/media-releases/2018/181128-african-swine-fever-reshaping-global-beef-markets/
https://research.rabobank.com/far/en/sectors/animal-protein/rising-african-swine-fever-losses-to-lift-all-protein.html
OIE Standing Group of Experts – Asia:
http://www.rr-asia.oie.int/disease-info/african-swine-fever/african-swine-fever-in-asia/standing-group-of-experts/201904-launch-mtg/
Animal traceability – US system:
https://www.feedstuffs.com/news/interactive-map-advances-animal-disease-traceability-program
Useful online resources
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