REVIEW ▶▶▶ ASF and partial depopulation


Dr Clayton Johnson, Carthage Veterinary Service, USA, called ASF the “ultimate horror story for vets”. He said that in the absence of a vac- cine, biosecurity is the only good strategy against ASF. He summed up elements that any biosecurity plan should have, including segregation – or building “firewalls” between farms or even within the farm. Discussing what would need to be done if ASF made it to North Ameri- ca, he said, “We have seen the impact of undercover activists. Activists on the doorstep is the last thing we want. So we may not be able to do a euthanasia process in a rapid manner, as it is not acceptable from a public standpoint. So we may have to choose options other than mass depopulations.” That is when he discussed “partial depopulation” – the idea being to avoid transmission. “So when building a barn, you should be thinking


about compartmentalisation, which would include smaller barns, indi- vidual room exit doors, segregated entries per barn and fewer shared areas. He said, “That means that when a farm is built there should be the ability to have pigs and carcasses re- moved without having to go through a common area.” He concluded by saying, “We should be proactive in considering alter- native control strategies that effectively eliminate ASF. We should de- fine thresholds at which partial depopulation would be an acceptable alternative to mass depopulation.”


Three pillars of biosecurity


Reduction, separation and commu- nication are the three main pillars of biosecurity, according to Pro- fessor Jean-Pierre Vaillan-


court, University of Montréal, Can- ada. Basically, he argued, the principles have been around for cen- turies, and he presented examples of


how past civilisations dealt with soldiers com-


ing back from the battlefield or how they treated lepers. Reduction of the source of infection, then separation of the sick animals, away from the healthy ones – and then good explanation as to why it was done. Dr Vaillancourt gave good examples of where the reduction part went


wrong, for example, by showing why footbaths can still lead to con- tamination if rules are not properly followed. That is why the third pillar matters – good information and communi- cation, he said. He showed a Google Maps picture of various farm sites close to each other. “An accountant would tell you there are three farms here. But when it is cold, when there is humidity, parti- cles go from farm to farm. In fact it is one big site. What we need to do is minimise disease transmission. An app with virtual geofencing might help.” Concluding, he said: “We have to do proper training and explain why. Adults will listen when they know why something is done. […] We need to look at innovative ways of reducing sources of contamination, separation and effective communication so we can have healthy pigs.”


Emerging diseases: Research remains important


“The reason you are all listening to me from your homes is related to an emerging disease: Covid-19,” said Dr Joaquim Segalés, from CReSA/ IRTA, Spain. He gave a definition of an emerging disease – either it is a disease that appears for the first time, or it is a disease that already exist- ed in nature, but has new incidents or occurs in a new geographical range. Most of these, he said, are caused by viruses. He summed up “re- cent” occasions of emerging pig diseases, like Porcine Reproductive and Respiratory Syndrome (PRRS), Porcine Circovirus type 2 (PCV2), H1N1 and Porcine Epidemic Diarrhoea virus (PEDv). He said, “But there is also a long list of potential agents we don’t know much about. Hepatitis, astrovirus, PCV3, PCV4; the list is almost endless. At the end of the day we have many potential candidates.” Bacteria are interesting to follow, he said. “Most of those bacteria are well


8 ▶PIG PROGRESS | Volume 36, No. 9, 2020


known. However, it became really in- teresting when PRRS came. It caused a modulation of the immune system.” In other words, known bacteria might suddenly cause a different re- action than they did before. He point- ed out that emerging and re-emerging diseases are not only a matter of changes in viruses but that it is often also important to take the environment into consideration. On that basis he called for more en- thusiastic research. “Everything depends on if you are looking for it or not. Every year three new infectious agents become known. Are they causing disease we have to worry about? Yes or no? We don’t know.”


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36