A pig-killing disease that has wiped out almost a billion pigs worldwide has mutated, establishing new variants.

Key points: The United Nations has warned of an increased risk of African swine fever spreading The disease has wiped out 800 million pigs worldwide New variants of the pig-killing disease have emerged in AsiaAustralia’s chief vet Mark Schipp said the new variant could have been established through the use of an illegal vaccine.

“As with any virus, we expect that there will be mutations and evolution of the virus in new environments, and it may be that this is a natural variation,” he said.

“But the deletions that we’re seeing in this virus are the same deletions that are being used in the development of vaccines.”

African Swine Fever does not yet have a vaccine.

“To develop a vaccine, they have been deleting specific genes and those specific gene deletions are some of those we’re seeing in the new variant, so it may be that this is arriving from illegal use of vaccines,” Dr Schipp said.

‘Less obvious signs of disease’Ahead of Chinese New Year celebrations, the Federal Government is calling for heightened biosecurity to ensure African swine fever (ASF), a disease that would devastate the pork industry, does not enter Australia.

“Variants are showing less obvious signs of the disease which increases the likelihood of it going undetected and uncontrolled,” said Agriculture Minister David Littleproud.

“The new variant is actually causing less mortality,” Dr Schipp said.

“[It is] a disease of chronic fatigue, slow growth, [and] reduced fertility — so if we’re relying on seeing lots of dead pigs as the first sign, we’re not going to see that sign.”

Mr Littleproud said the emergence of new variants of the virus had reportedly been detected in Asia but did not specify where.

More than 11,600 outbreaks of ASF have been detected in Asia since 2018, and incursion in Australia could cost the domestic economy up to $2 billion over five years, according to a study funded by Australian Pork Limited.

There are currently more than 3,000 ongoing outbreaks of ASF in Asia.

It is a contagious viral disease which affects domestic and wild pigs, but not humans.

In addition to high fever, symptoms include internal bleeding and haemorrhages on the skin and the virus is estimated to have killed 800 million pigs worldwide.

Fear over imported productsThe Government and pork industry fear that the disease, which is transmitted in pork products, could enter Australia via mail or travellers.

Pigs huddling together, six days after infection with African swine fever.(Supplied: The Pirbright Institute)In the 14 months until the end of 2020, more than 40 tonnes of pork products were intercepted from air travellers, and more than 9t were intercepted at Australian mail centres.

In less than two years, since new biosecurity penalties were introduced, 14 travellers have been kicked out of Australia and had their visas cancelled for attempting to illegally import produce.