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African Swine Fever: learn the facts, save your pigs

03 November 2017

With the rapid emergence of cases of African swine fever identified within Europe, it is important to maintain high standards of biosecurity, know the signs of the disease, and, equally as critical, know how to stop the spread.

African swine fever (ASF) was first described in 1921 and has since been identified in 28 sub-Saharan African countries. Between 1957 and 1995, ASF cases emerged in countries around the world; namely Brazil, Haiti, Dominican Republic, Belgium, the Netherlands, Spain, Portugal, Malta, France and Italy. Each country managed to control and eventually eliminate ASF from wild and domestic swine populations, except the Italian island of Sardinia, where the virus is endemic. In 2007, new cases of ASF emerged in Georgia and, subsequently, the virus was identified on farms in Azerbaijan, Armenia, and eventually reached Russia. Ukraine was next to be hit in 2012, and from there ASF was swiftly introduced to Belarus in 2013 where it continued its expanse into Estonia, Latvia, Lithuania and Poland in 2014. Cases of ASF were identified in Moldova last year (2016), and 2017 has seen a drastic increase in formally diagnosed cases within Central and Eastern Europe. The virus was identified in the Czech Republic this year (2017) after vets began sampling wild boar carcasses.The pig (and its close relatives, boars and hogs) is the only natural host of the double-stranded, Asfarviridae family of viruses, meaning the virus does not cause harm to humans or other animals. This does not mean that humans and other animals cannot spread the virus as carriers; African Swine Fever (ASF) is commonly carried by arthropods, such as the soft-bodied tick, through uptake of blood from infected pigs.

Contamination generally occurs via direct contact with tissue and bodily fluids from infected or carrier pigs, including discharges from the nose, mouth, urine and faeces or infected semen. It also spreads through transport and consumption of contaminated pork products, and some cases have originated from failure to comply with biosecurity standards by feeding waste food to domestic pigs. It is believed that a highly pathogenic strain of ASF was introduced to domestic pigs and, subsequently, wild boar populations in the port of Poti, Georgia, in 2007 when waste food from a ship originating in South Africa was fed to local pigs.

Although the virus in wild boar and hogs does not manifest any signs of the disease, it remains highly contagious across all swine species and can survive in pigs for long periods of time post-slaughter – even in frozen carcasses. It is also important to note that curing and smoking pork products does not destroy the virus.

It is vital to immediately distinguish the disease that is infecting a herd; ASF and Classical swine fever are caused by very similar viruses which are only distinguishable by laboratory testing. Notifying a vet as soon as any signs arise is the best way to ensure the correct quarantine and treatment procedures are followed – it could save the rest of your pigs.

 

Some common signs

General signs: - High fever 40-42°C
                        - Loss of appetite
                        - Depression
                        - Vomiting and/or diarrhoea
                        - White skinned pigs: extremities (nose, ears, tail and lower legs)                           become cyanotic (blue-purple colour)
                        - Discrete haemorrhages appear in the skin particularly on the                               ears and flanks
                        - Group will huddle together and are usually shivering
                        - Abnormal breathing
                        - Heavy discharge from eyes and/or nose
                        - Lethargic- sometimes refusal to stand or move
                        - Very unsteady when stood up
                        - Comatose state and death within a few days
Pregnant sows commonly undergo miscarriage or deliver stillborn piglets that are malformed – piglets can be tested for the virus.

African Swine Fever symptomsMortality rate in infected groups of pigs is high and there is no vaccination proven to prevent or cure infection, therefore, it is crucial that control begins on-farm. European, South American and Caribbean countries which have been infected have adopted a slaughter policy to eradicate the virus within the herd. Mild strains of the virus also occur which cause a milder but equally serious disease in domestic pig herds – individuals from these herds must also be slaughtered to prevent pathogenesis.

 

Steps for prevention

- Do not feed domestic pigs food waste; this is illegal in the UK, other EU regions and some states within the U.S.

Where ‘permitted garbage feeding’ is legal in U.S. states, pigs fed this way are prohibited from exportation.

- Do not leave food waste exposed for wild swine species to access. Dispose of food waste properly.

- Abide by strict biosecurity rules. Do not take pig meat onto farms, or restrict all food (and consumption of food) to a canteen. All staff on farm should be inducted onto a strict programme of hand and equipment sanitisation before and after contact with pigs.

- Follow rules and regulations on disposal of food waste at ferry ports and airports.

- Provide the means for staff and visitors to thoroughly sanitise their hands and equipment.

- Ensure that wild boar, warthogs and wild pigs, and materials potentially contaminated by such wild species do not come into contact with domestic pigs.

- Check infected regions before import of goods that could potentially be contaminated.

- Advise and educate people on the risks of bringing back pork products from infected regions.

 

To learn more about African swine fever, visit The Pig Site Knowledge Centre

To check any signs you are worried about, head to The Pig Site Disease Problem Solver

APHA Campaign: catering waste ban

 

Reference: Arias M, Jurado C, Gallardo C, Fernandez-Pinero J, Sanchez-Vizcaíno JM (2017). Gaps in African swine fever: Analysis and priorities. Transbound Emerging Disease.

Image Credit:

'Some common signs': USDA Animal and Plant Health Inspection Service (left - cyanotic ear)

Laura Gil Martinez / IAEA (right - emaciated pig with eye and nasal discharge)

 

The Pig Site Editor

 

 

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