Chinese scientists have detected two new variants of the African swine fever virus (ASFV) that may render control of this disease even harder to achieve.
The findings of the research, conducted at the country's Harbin Veterinary Research Institute, were released in late February and showed the two evolving virus strains were highly transmissible - but less virulent than the dominant strain.
This makes them more challenging to identify.
It came as no surprise to the researchers to find complex genetic diversity in the field, considering the vast population of pigs in China and the widespread prevalence of African swine fever (ASF) in the nation's pig population for more than two years.
The scientists took 3660 samples from farms, abattoirs and disposal plants across seven provinces in the second half of 2020.
They isolated and distinguished 22 viruses belonging to the ASFV genotype and all had mutations, gene deletions or replacements compared to HLJ/18 - which was the original isolate detected in China in 2018.
But it is the emergence of the two lower-virulent, natural mutants that creates the greatest challenge for ASFV control because signs and symptoms of the new variants are far more difficult to recognise in the field.
And low virulence does not mean lower risk, as the emerging strains are just as deadly as the original variant.
Despite constant promises, there is still no commercially available vaccine for the control of ASFV in China.
So, disease management relies on early and rapid detection, then the immediate culling of infected animals.
But experts say low standards of biosecurity, lack of an industry-wide oversight regime and local government cover-ups of outbreaks have allowed the disease to spread.
Before the outbreak of ASF, the swine population in China was 435 million head - or about 50 per cent of the global herd.
Officially, this fell 42 per cent to about 254 million head at the peak of the outbreak and led to farm closures and a severe shortage of pork for Chinese consumers.
Some unofficial reports put the reduction in animal inventory even higher, at about 60 per cent of pre-ASF levels.
China accounts for almost 50 per cent of the world's consumption of pork.
The pig supply shortfall pushed domestic prices to record levels in 2020 as the economy also recovered from the COVID-19 virus.
Imports increased substantially and the government was forced to tap into pork reserves to fill the supply gap and quell rising prices.
The Chinese government has been quite bullish and vocal about the recovery of the pig herd.
The agriculture ministry recently announced it expected sow and pig numbers would be back to pre-ASF outbreak levels by the middle of 2021.
But Simon Quilty, of Global AgriTrends, doubts this optimism.
He believes a second wave of ASF has killed between seven and eight million sows in the past two months alone, putting a severe brake on the resurgence.
Despite the elevated quarantine regimes, and the swift development of big state-of-the-art piggeries, there are still many challenges ahead for the pork industry in China.
And, according to Mr Quity, there is a lot of data suggesting the government rhetoric differs significantly from the real picture. Who would have thought?
Domestic piglet prices recently hit 98 renminbi (RMB) per head, which is almost four times the 25RMB that was being paid prior to the outbreak in 2018.
This is hardly a rational price reaction to ample supply.
Similarly, hog prices are more than double those of pre-ASF prices at 30-40RMB per kilogram. And breeding sows are about 2.5-times the early 2018 price.
China's protein shortage is also reflected in domestic meat prices, with pork currently retailing at about 135 per cent higher than the average price paid in the three years before the ASF outbreak.
The retail price of beef is more than 40 per cent higher than the same base period.
Chinese meat imports have also soared.
According to Chinese government data, imports of pork, beef and chicken (combined) in 2017 reached 2.7 million tonnes.
By 2020, that was up by more than 325 per cent to 8.8 million tonnes - and was due primarily to the plunge in domestic pork production following the ASF outbreak.
The trend has continued into 2021, with China importing 1.6 million tonnes of meat in January and February. This was a 27.6 per cent jump from levels of a year ago.
Now, the new multi-storey "super-piggeries" that have been built to increase efficiencies and improve disease control by shifting production away from smaller backyard operations, has become the challenge.
These house a huge number of breeding sows and followers. But they are also an excellent incubator for the ASF disease when it infiltrates the system.
If one farm gets infected, the production loss is huge compared to that from a small family-run operation.
Ironically, China's first hog breeding exchange traded fund (ETF) debuted on the Shenzhen Stock Exchange last Friday.
Trading as Penghua Fund Management's CSI Livestock Breeding Co's ETF, it is the first of three tied to the country's pork sector.
The pork sector is attracting significant investment interest on the back of the high domestic prices.
So, what impact will the latest outbreak have on Chinese feed grain demand?
Much has been made of the massive up-tick in import volumes, particularly for corn, and - to a lesser extent - to wheat, in the past 12 months.
But this is not all about the recovery in the country's pig herd.
In fact, it is more about historically poor management of the country's inventory.
Back in early 2016, the Chinese government made a significant policy change.
It decided to cease subsidising domestic corn production by allowing prices to be set by the market while, at the same time, auctioning-off the strategic reserves.
But it seems the government took its eye off the ball.
Domestic demand increased, but production plateaued.
Feed grain inventories went from burdensome in 2015 to tight in 2018.
Beijing needed to replenish the stockpile by slowly growing imports.
Enter Donald Trump and the China-US trade war, which stymied the campaign.
The outbreak of ASF, and then COVID-19, conspired to further derail the inventory rebuild process.
Despite the latest ASF outbreak, low feed grain reserves will continue to drive China's import demand for corn and wheat in the short-term.
The commodity at greatest risk of an ASF-led fall in Chinese demand could be soybeans, as the pork industry is the biggest driver of soybean meal demand.
The US export campaign is all but done, so this would likely manifest itself in a deferral of Brazilian exports for the balance of the 2020-21 marketing year.
