Meet the Expert

“During winter time, the African swine fever virus may persist up to five months in the bone marrow of a wild boar's carcass”

A significant reduction in Europe’s wild boar populations and good biosecurity on all swine farms are necessary steps to combat African swine fever, Professor Zygmunt Pejsak emphasises in this Meet The Expert podcast. Professor Pejsak was head of the swine diseases department at the National Veterinary Institute in Poland when ASF first entered the country across its Eastern border. He discusses strategic options against the disease and makes the case for having effective surveillance in any affected or potentially affected country to control the possible introduction of a novel virus genotype.

“The direction of wild boar movement in general is to the Western territories...it means from Russia to Belarus, from Belarus to Poland, from Poland to Germany and probably will be from Germany to France”

As the Head of the Department of Swine Diseases at the National Veterinary Research Institute until his retirement, Professor Zigmunt Pejsak in Poland played a central role in the country's battle against African swine fever. In conversation with journalist Peter Best, he discusses how the ASF virus has travelled from East to West in European wild boar populations and the possibilities for its further spread.

“We plan a quarantine time of a minimum eight weeks and if we use MLV PRRS virus vaccines, we prefer around 12 weeks”

Gilt introduction procedures are discussed by Danish swine veterinarian Dr. Kristian Havn in the context of a herd averaging 1,000 sows with an annual replacement rate of 45-50%, meaning a need to bring in 500 replacement gilts per year. A target of introduction to the sow herd at 34 weeks old dictates that gilts must be no older than 22 weeks on arrival, to accommodate a 12-weeks quarantine period. How to expose them to herd pathogens is still an open question, he says, because we will want them to produce an adequate level of antibodies in their colostrum when they eventually enter the farrowing room.

“Gilts can be the best reproductive performers on the farm in terms of conception rates and farrowing rates --- if they are not the best, there’s an opportunity there for us to go work on”

For larger sow systems, a group-based gilt preparation process from weaning at 6 kilograms to breeding at 135 kg is detailed in this conversation in the United States with Dr. Clayton Johnson, veterinarian partner and Director of Health at Carthage Veterinary Services. Health acclimation should begin as early as possible, he tells us. Ideally therefore, bring prospective herd replacement gilts into an isolation barn when they are weaned. Groups would consist of four weeks’ worth of gilts, with the animals tagged to identify their birth week. Isolation is followed by time in a developer barn, until gilts weighing at least 120 kg when showing first oestrus are judged ready to move to the gestation area.

“It’s important that pathogen exposure occurs early enough in the gilt’s life so she recovers from the infection, stops shedding the pathogen and is immunocompetent at the time of farrowing”

Divide the young gilt’s time before breeding into the separate categories of development and acclimation, says Dr. Clayton Johnson of Carthage Veterinary Services in the U.S.A. Development aims to prepare her physiology for a future in reproduction, acclimation tries to arm her immune system to cope with the pathogens in the sow herd. Target at least 680 grams of gain per day in the gilt developer phase. How acclimation is handled needs to be specific to each pathogen and each herd.

“It is a totally new challenge for the feed industry --- a number of feed components can be quite a good environment for the virus, which can stay infectious for a longer time”

In our final conversation about ASF with Dr. Tomasz Trela, technical manager for swine at Boehringer Ingelheim's regional centre covering Central and Eastern Europe, he emphasises the evidence connecting ASF infection to feed sources. These could be green crops harvested from contaminated fields, but also the virus has been detected in feed-mills in some countries and delivery vehicles may need to be diverted around hot-spots where infected wild boar are found.

“ASF virus is very resistant to physical and chemical factors, this means it can stay infective for weeks or even months”

The resistance of the virus and the difficulties of decontamination are just two of the issues facing swine farms that are located in an area where the infection is known to be present, says Dr. Tomasz Trela, Boehringer Ingelheim's technical manager for swine in Central and Eastern Europe. Quite new for swine veterinarians is the situation where wild boar represent a huge reservoir of pathogens surrounding the farms. All potential carriers of the virus onto a farm must be considered.

“We have re-introductions of diseases in some of our farms every year, so something must be able to improve biosecurity...our plan is to evaluate all 1,220 farms that we consult”

Dr. Kristian Havn is a swine veterinary practitioner with the Porcus practice in Denmark who has pioneered an innovative programme to improve biosecurity on the swine farms that he advises. In English, the programme’s name translates at Pathogen Stop. Its basis is an online survey form completed by the veterinarian in consultation with the farmer. The original idea was to make a system for evaluating biosecurity at farm level regarding PRRS virus, Dr. Havn explains in this podcast. But it has been extended to cover all pathogens, including APP, swine influenza, mycoplasma and even African swine fever.

“Biosecurity is the only tool we have now to protect our pigs against ASF”

Precautions for protecting the farm against the entry of the African swine fever virus are explained by Dr. Tomasz Trela, the Boehringer Ingelheim technical manager for swine in Central and Eastern Europe. Based on the experiences of swine farms in Europe and Asia, he warns of the ways in which that the virus can be carried in, such as on vehicles and feed. More conversations with Dr. Trela about ASF feature in other Meet The Expert podcasts.

“African swine fever is a very slow disease...we have the experience during outbreaks that not all pigs become infected”

Dr. Tomasz Trela, the technical manager for swine in Central and Eastern Europe at Boehringer Ingelheim's regional centre in Vienna, shares his personal observations of European and Asian sow farms suffering an outbreak of African swine fever. This first episode covers on-farm lessons regarding the recognition and diagnosis of the disease; in a further Meet The Expert podcast he discusses implications for biosecurity at farm level.