Hundreds of pigs have been reported dead on the Indonesian island of Bali, as the Philippines confirmed a new outbreak of the deadly African swine fever.

Key points: A quarter of the world's pigs are thought to have been wiped out by the disease

A quarter of the world's pigs are thought to have been wiped out by the disease Authorities remain concerned that African swine fever could spread to Australia

Authorities remain concerned that African swine fever could spread to Australia Scientists say an experimental vaccine developed in the US looks promising

Authorities in Bali reported 888 pig deaths in Bali as of January 31. Many of the pigs exhibited similar symptoms to the highly-contagious African swine fever (ASF) — high fever, vomiting, and diarrhea.

While they have not been confirmed as cases of ASF, local producers say demand for pork has steeply declined.

"This is an extraordinary event, greatly impacting farmers and consumers," said Ketut Hari Suyasa, chairman of the Indonesian Pig Farmers Association, as quoted by local media.

Blood samples from the dead pigs were being tested to determine the cause of death, authorities said.

Indonesian officials confirmed the first outbreak of ASF in December, spurring fears that the disease could reach Australia and leading to stricter biosecurity measures.

At least 30,000 pigs have died in the province of North Sumatra, where the pig population is 1.2 million.

Pork features heavily in the Balinese diet. ( Flickr: Kai Hendry )

In Hindu-majority Bali, suckling pig known as babi guling is a local delicacy commonly enjoyed by tourists.

Unlike swine flu — also known as H1N1 — ASF does not pose a threat to human health. Nevertheless, humans can transmit the disease if their clothing and boots have been contaminated.

Fever spreads throughout the Philippines

Authorities in the southern Philippines province of Mindanao confirmed that around 1000 local pigs had died due to ASF.

The municipality of Don Marcelino is in lockdown, with the sale and transport of pigs, pork and pork by-products temporarily banned.

Pig farmers could be set for high pork prices as global stocks fall thanks to African swine fever. ( ABC Rural: Tom Edwards )

"Backyard pig farmers in the area practice group rearing of hogs, from different owners, most [of them without] proper housing provisions nor biosecurity practices," said the Philippine agriculture ministry.

Agriculture secretary William Dar has suggested that pork smuggled from China could be behind the outbreak in the Philippines.

The Philippines, which is the eighth largest pork producer in the world, recorded its first swine fever case in September last year, leading to at least 20,000 pigs being culled.

Cases of ASF have been reported across the country including in the capital Manila and surrounding areas.

Disease has devastated global pig population

African swine fever is a viral contagious disease which affects domestic and wild pigs.

In addition to high fever, symptoms include internal bleeding and haemorrhages on the skin.

There is no vaccine and it kills about 80 per cent of the pigs it infects. It is thought to have wiped out more than a quarter of the global pig population in 2019.

In China, which is the world's largest pork producer, it is estimated that 50-60 per cent of its pig population was decimated last year.

ASF was first reported in the Liaoning province of China in August 2018, and local authorities killed more than a million pigs in 2019 to curb the spread of the disease.

The cost of pork has increased by at least 40 per cent due to the spread of ASF, and the cost of other meats is also expected to rise as Chinese consumers turn to chicken, lamb and beef as alternative sources of protein.

Australian authorities have been on high alert for months amid fears the arrival of the disease is inevitable.

If African swine fever reaches Australia, it could cost the pork industry more than $2 billion. ( ABC News: Jess Davis )

Risk to Australian livestock

The fever has been reported in around 50 countries, including China, Belgium, Slovakia, Cambodia, North Korea, South Korea, and Vietnam.

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The spread of the disease has also reached Timor Leste, a nation less than 700 kilometres from Darwin, posing an increased risk to Australia.

Australia's chief veterinary officer, Mark Schipp, has emphasised that the country has good biosecurity systems at both the border and on its farms that could keep the disease out.

In December, the Australian Government announced an extra $66 million dollars worth of funding to boost biosecurity at Australia's borders against ASF.

This included the deployment of more biosecurity officers, six new detector dogs, and two new 3D X-ray machines at mail centres in Sydney and Melbourne.

Nevertheless, Dr Schipp said in November that "it's the biggest threat to the commercial raising of pigs we've ever seen."

"It's the biggest threat to any commercial livestock of our generation."

The pork industry provides around 34,000 jobs nationwide.

Authorities reported confiscating at least 32 tonnes of cooked pork products at Australian airports last year.

Margo Andrae, chief executive of industry body Pork Australia Limited, has said that almost 50 per cent of seized pork products contained traces of ASF.

A Vietnamese woman was deported in October last year after attempting to smuggle 4.6 kilograms of uncooked pork and other food items into Australia.

Australians caught bringing in pork products could face criminal prosecution or civil court action, and be ordered to pay up to $420,000 and be sentenced to up to 10 years in jail.

Precautions elsewhere

At least nine countries in Europe are affected by ASF, and the European Food Safety Authority has warned that it has continued to slowly spread.

In Germany, authorities in the state of Brandenberg have constructed around 120 kilometres of electric fencing to prevent wild boars from crossing the border with Poland and infecting its herd with ASF.

An experimental vaccine developed by the New York-based Plum Island Animal Disease Centre is proving more effective than previous vaccines, according to a study published in the Journal of Virology last month.

Douglas P Gladue, one of the lead researchers, said that the vaccine "shows promise, and offers complete protection against the current strain currently producing outbreaks throughout Eastern Europe and Asia."

CSIRO is also researching a vaccine, but has warned an effective vaccine could be at least five years away.