African Swine Fever: The biosecurity gap we still don’t talk about

ASF transmission through people — a much bigger problem

A long-standing concern surfaced at the Ukrainian–Danish biosecurity conference: African swine fever can pass between animals via bacteria carried by ordinary people. Vets, zootechnicians, drivers — anyone who walks onto a farm. The standard biosecurity system simply isn't designed for this threat.

2024 was one of the hardest years on record for Ukrainian pig production. Various estimates put the country's losses at up to 40% of the herd. Tellingly, it wasn't only small farms without proper protections that suffered — the virus also reached operations that had spared neither money nor effort on biosecurity.

Dan-Farm Ukraine, a Danish pig operation active in Ukraine since 2001, runs sites in the Kyiv and Zhytomyr regions and ranks among the country's twenty largest pork producers. Its parent holding, Agro East A/S, brings together around 70 Danish farmers — people who know the price of discipline on a farm. And still: ASF. The standards were in place, the procedures were followed, and the virus came anyway.

The virus is always there, outbreak or no outbreak

Andriy Buzun, professor of epizootology at the National Academy of Agrarian Sciences of Ukraine, set out the mechanism in detail.

ASF has two modes of existence. The first is the one everyone knows about: mass mortality, herd culling, quarantine, financial losses. This is the active form, and it is what every current protocol is designed to counter.

But there is also a second mode — a proactive one. Between outbreaks, the virus does not disappear; it shifts into an inconspicuous, low-pathogenic state and hides among certain types of bacteria. Pigs go on living, eating and growing with no symptoms at all, while the virus sits on their bacteria and waits.

'We are fighting an African swine fever that hides skilfully among bacteria,' Buzun says. 'It's like the Cheshire Cat's smile — the cat seems to be gone, but the smile is still there.'

Here is what that looks like in practice. One piglet at a teaching farm lived through three consecutive ASF outbreaks. Whole herds around it were being culled; the piglet stayed alive. When it was finally taken to the laboratory, the test came back positive for ASF. Not a single clinical sign — but the virus was there. That is the proactive form.

How a human becomes a carrier

Experimental data from Buzun's team show that the bacteria among which the virus hides — virophoric bacteria — settle on the tonsils and on the mucous membranes of the respiratory tract, including in humans. A person can therefore become a carrier of these virophoric bacteria, and thus a vector for the virus itself. From farm to farm. Without symptoms, and without any awareness of it.

Showers at the entrance, disinfection mats, separate clean and dirty zones, separate workwear — these are all effective against most threats. But once the worker themselves becomes a potential carrier, those measures miss the target, because they were never designed for this scenario. That is precisely why, in a country with viral contamination of the food chain, even farms with exemplary biosecurity get outbreaks that appear to come from nowhere.

Old rules that are long overdue for change

The regulatory framework still in use in Ukraine and in the EU was written in the 1970s. Back then, ASF existed only in domestic pigs and had not yet entered the wild, and the fact that the virus can survive inside bacteria and be transmitted through people was simply not known — for the straightforward reason that it had not yet been studied.

Since then, the picture has changed completely. The virus is long since out in the wild, the wild boar has become its main reservoir, and the science has moved on a great deal. The rules have not.

Buzun also pointed out that as far back as 2014–2015, his group used mathematical modelling to predict precisely how ASF would spread across Ukraine and Europe. The forecast proved almost exactly right. It was ignored at the time — and the industry paid the price.

The vaccine is no cure-all — but it's the only thing that closes this particular gap

If the virus can reach a farm via a person whom no protocol can stop, then the protection has to work inside the animal itself — regardless of where the pathogen came from.

That is what a vaccine is for, and it needs to be used not after pigs have started dying but before: when serological testing shows the virus is already present, but clinical signs have not yet appeared. The EU has long had a name for this approach: metaphylaxis.

Spain is the only country in Europe to have defeated ASF — the result of eight years of work: regular serology, timely culling of suspect stock, a systematic approach. The vaccine is now being added to that recipe.

Back in 2021, Buzun's team had its 'StopASFmix' methodological guidelines approved through the pharmaceutical commission — a working document on the early warning of outbreaks. The team is now proposing to add vaccination to it and to test the protocol jointly with the Danish partners — on a real farm, with real data.

Tellingly, while the debate continues in Ukraine, Vietnam — a country that lost 6 million pigs in six months to the same ASF genotype II that is circulating here — has already taken its own commercial vaccine to mass production. In March 2026, a Ukrainian trade mission met with AVAC Vietnam and received a direct offer: buy a trial batch of the AVAC ASF Live vaccine and run your own tests; don't wait for the EU to start vaccinating against ASF, because your situations are very different.

Why Ukraine's experience matters for the whole of Europe

Until recently, the conversation about the vaccine looked like a dispute between scientists and regulators. Now business is actively joining it — business that has already suffered serious losses through delay and debate.

Danish investors did not leave Ukraine after 2024. They want to keep working here — but not on blind luck. There is no compensation for pigs lost to ASF in Ukraine. And the fact that Ukrainian business is now publicly backing ASF vaccine prophylaxis is no longer a scientific argument. It is a signal from people who know what a mistake costs and who want to change the situation.

The scientific case for the vaccine is there. The practical demand from the industry is there.

A Security Fund of the United Council of Ukrainian Pork Producers and Processors has been set up in Ukraine, and businesses and interested institutions from EU countries are welcome to join it. Ukraine's experience of fighting African swine fever through ASF vaccine prophylaxis can be of service to the whole of Europe.

Contacts for the United Council of Ukrainian Pork Producers and Processors

web: https://ukrainepork.com/

email: official@ukrainepork.com