African swine fever (ASF or ASF, African Swine Fever) has also resumed its spread in continental Europe. It is a disease that is harmless to humans but highly contagious in pigs, where it causes high mortality.
The Asian continent has suffered huge losses, with a terrible impact on the global market. In fact, pork is the second largest source of animal protein globally, after poultry and eggs.
Recent outbreaks in Germany, the leading pork producer on the old continent, have also triggered a high alert in Europe. In the face of the risk of a crisis in the entire swine livestock industry, with irreparable damage to the sausage industry as well. Insight.
African swine fever in Europe, historical courses and recurrences
African Swine Fever (ASF), native to subequatorial Africa, was first reported in Europe in the middle of the last century. Brief history:
– 1957, ASF registered in Lisbon. From there it shortly spread to the Iberian Peninsula, where within 5 years it was eradicated,
– 1978, Sardinia. Swine fever is declared endemic, still awaiting eradication (see last paragraph),
– 2007. An outbreak in Georgia spreads to Armenia, Azerbaijan, Iran, Russia, and Belarus,
-2012. A new contagion, from Ukraine to the Baltic republics, Romania, the Czech Republic, and beyond,
– 2014. Swine fever appears in Poland, where it reappeared in 2019 and still persists,
– 2016, Moldova,
– 2017, Czech Republic and Romania,
– 2018, Hungary, Bulgaria, Belgium,
– 2019. Slovakia,
– 2020. Serbia, Greece and Germany. After the first case among wild boars in the state of Brandenburg, confirmed on 11.9.20, 13 more infected wild suidae are identified in Neuzelle, near the Polish border.
The Asian disaster
ASF, or PSA, is endemic in sub-Saharan Africa. And it has spread in recent decades in Europe, Latin America and the Caribbean. But Asia is the continent where it has experienced a true slaughter of pigs, estimated by OIE(World Organization for Animal Health) at 82 percent of total losses between 2016 and 2020.
The year 2018 marked the beginning of disaster in China, where the disease has spread to all 31 provinces. Followed by Mongolia, Vietnam, Cambodia, Hong Kong, Democratic People’s Republic of Korea, Laos, Burma, the Philippines, South Korea, Timor-Leste and Indonesia in 2019. Papua New Guinea and India, in 2020.
The contagion
ASF infection is transmitted by direct contact (via feces) and indirectly, through contaminated kitchen waste or by ingestion of meat from infected animals (more rarely through contaminated materials and equipment). The disease can also be transmitted by soft ticks of the genus Ornithodoros. Some authors speculate a secondary role in disease transmission by mechanical vectors such as fly flies.
Wild pigs and wild boars have played and still play an important role in contagion, in various territories, as reservoirs and sources of swine fever. In fact, the virus from the wild population spreads to domestic ungulates and wild boars. Which in turn can reinfect the brady, thus determining the endemicity of the disease. The main mode of infection is orofecal, although the virus can also spread by other routes (respiratory and cutaneous, more rarely genital).
The disease
The disease can manifest with hyperacute, acute, subacute, chronic, and inapparent clinical pictures. The most typical forms are the hyperacute or acute forms, which result in the death of sick animals within 3 to 10 days, sometimes even before obvious clinical symptoms appear.
In the acute and subacute form, only a few animals on the farm initially become ill, presenting fever as the main symptom. The infection then spreads to all heads, with loss of appetite and walking difficulties (nonspecific symptoms). (1)
In the last stage of the disease, the animal may exhibit neurological symptoms (ataxia and paraparesis), with hind limb paralysis and seizures. As well as skin hemorrhages, usually in the form of petechiae i.e., blotches and suffusions on the ears, inner face and extremities of the limbs, belly and tail (specific symptoms). In pregnant sows, SMEDIA syndrome occurs. Digestive symptoms (vomiting and diarrhea), conjunctivitis and respiratory symptoms may also appear.
Chronic and inapparent forms
In the chronic form of the disease, symptoms are extremely variable; affected animals may become thinner with no apparent cause or have fever that can range from 39-40 °C. Affected animals may come to death after many weeks of illness.
Clinical forms of African swine fever include the inapparent form, in which animals can become infected and show no symptoms. And yet they can remain infected, asymptomatic and healthy carriers, posing a danger of spreading the virus in the environment.
Injuries
Anatomopathological lesions following acute and subacute forms of African swine fever are diffuse hemorrhages to various organs such as spleen, kidney, heart, and lymphatic ganglia. Upon opening the carcass, hemorrhagic spreads may be evident, especially in the thoracic and abdominal cavities. The spleen appears increased in volume and hemorrhagic with changes in color and consistency.
The kidneys have a characteristic appearance with punctiform hemorrhages spread over the entire surface and varying in shape and size (turkey egg-shaped). The lymph nodes (renal, epigastric, meseraic, and the mediastinal) in turn have hemorrhagic blood clot-like lesions. Hemorrhagic enteritis with petechiae and diffuse hemorrhages throughout the intestine can be found.
Arduous diagnosis, treatment and vaccines absent
Diagnosis of African swine fever can present considerable difficulties because the same symptoms can be found in other swine diseases such as PSC (classical swine fever), food poisoning, anticoagulant poisoning, respiratory syndromes, Aujesky’s disease, mal Rosso, and salmonellosis.
The immunological peculiarities of PSA/ASF virus are very important in order to determine its control, as it does not induce the production of neutralizing antibodies in the body. Consequently, it has not been possible so far to make a vaccine (as it has been for classical swine fever, so-called hog cholera, and other viroses). Nor any other means of care. Therefore, prevention remains the only available tool to date.
Prevention
In the absence of vaccines and/or veterinary drugs that can halt the epidemic die-off of suids, the focus is on prevention. Some insights to follow.
1) Veterinarians. Maximum alertness and attention to reports of suspicious herds or even minimally suspicious animal entries to the slaughterhouse.
2) Transporters. Disinfect the means of transportation before and after loading. Do not forage animals while moving with leftover food.
3) Hunters. At the outcome of hunting trips, the captured carcasses must dutifully undergo a health examination. Inquire about the existence of risk areas and especially take sanitation measures for shoes, clothes, equipment and transportation means.
4) Citizens. In case of sightings of suidae carcasses, notify the Veterinary Services of the Local Health Authority immediately. Or at the very least, law enforcement agencies, carabinieri foresters, traffic police, etc.
5) Tourists and travelers. Always avoid eating meats and cold cuts of unknown origin or otherwise not certified. (2) And above all, absolutely refrain from carrying souvenirs of animal origin.
EFSA, information campaign in the Balkans
TheEuropean Food Safety Authority (EFSA ) launched an information campaign on African swine fever in August 2020, in the Balkans, with the support of CLITRAVI(the Liaison Centre for the Meat Processing Industry in the European Union).
The information campaign is aimed at countries on the Balkan Peninsula. Albania, Bosnia and Herzegovina, Croatia, Greece, Kosovo, Montenegro, North Macedonia, Serbia and Slovenia. Its recipients are first and foremost farmers, hunters, and people who come into contact with ungulates, domestic and otherwise (wild boar, wild pigs). As well as veterinary organizations, inspection authorities and border police, local governments, tour operators and travelers.
The keywords of EFSA’s campaign are Detect, Prevent, Report. Detecting, preventing, and reporting possible outbreaks are essential to mitigate the expansion of this disease. Fact sheets, infographics, social media posts and other materials are available on EFSA’s dedicated African swine fever website.
African swine fever in Sardinia
In Italy , African swine fever has been present only in the territory of the Sardinia region since 1978. Regionalization and the containment measures established for this purpose have made it possible to implement The National Plan for Eradication of ASF through regional measures, under the supervision of the Ministry of Health. So as to ensure the free movement of animals and meat from other autonomous regions and provinces in the past four decades.
At present, Sardinia is one step closer to the historic achievement of ASF eradication, thanks to the establishment of the Regional Project Unit (RDP) and the implementation of the special extraordinary program. (3) The last outbreak among domestic animals, in Mamoiada (NU), died out in September 2018. While in Baunei (NU), in November 2019, the last case of seropositivity was recorded. Among wild boars, the last positive finding for the virus was in April 2019, in two wild boars found dead in the municipality of Bultei (SS). Pork and sausages remain subject to a ban on transport and sale outside the island.
Interim conclusions
The OIE–World Organization for Animal Health–has defined appropriate precautions and standards to be followed to control African swine fever. Starting with early surveillance and reporting of new outbreaks.
Strict adherence to OIE standards is crucial to mitigating the impacts of ASF on animal health and the economies of the countries involved. And it must therefore come to be regarded as a key priority in the European Union’s trade policy-as well as animal health and sanitation policies.
Dario Dongo, Carmela Mele, Alfonso Piscopo
Notes
(1) Although some individuals may overcome the disease, they nevertheless remain carriers of the virus and subsequently infect healthy pigs
(2) See the general precautions stated in the previous article https://www.greatitalianfoodtrade.it/sicurezza/alimenti-crudi-e-freschi-buone-prassi-anti-covid
(3) The Regional Project Unit (RDP) was established by resolution of the Sardinian Regional Council 25.11.14 no. 47/3. Its responsibilities were defined by Regional Law 34/2014
Bibliography
Sànchez-Cordòn PJ, Montoya M,Reis AL, Dixon LK. (2018). A re-emerging viral disease threatening the global pig industry. The veterinary journal. https://doi.org/10.1016/j.tvjl.2017.12.025
Dixon LK, Stahl K, Jori F, Vial L, Pfeiffer Du. (2020). African Swine Fever Epidemiology and Control. Annu Rev Anim Biosci. 2020 Feb 15;8:221-246. doi: 10.1146/annurev-animal-021419-083741. Epub 2020 Nov 19. PMID: 31743062.
Gallardo C, Fernández-Pinero J, Arias M. (2019). African swine fever (ASF) diagnosis, an essential tool in the epidemiological investigation. Virus Res. 2019 Oct 2;271:197676. doi: 10.1016/j.virusres.2019.197676. Epub 2019 Jul 27. PMID: 31362027.