African swine fever (ASF), which is caused by African swine fever virus (ASFV), has recently spread through Asia. This is considered the worst livestock pandemic in history.
In its wake, millions of pigs have been killed from the disease and, to prevent the disease spreading, pork production has been lowered. This is devastating people’s livelihoods.
An ASF outbreak in Australia would have a significant impact on pig health and production in Australia. There would be wider economic impacts, including loss of access to overseas markets for our pork products.
The Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) report, Potential economic consequences of African Swine Fever in Australia, estimated a small-scale outbreak in domestic pigs followed by eradication of the disease would cost between $117 million and $263 million.
We spoke to Dr David Williams, an expert in ASFV at our Australian Centre for Disease Preparedness (ACDP), to find out what we are doing to help combat ASF.
What is African swine fever?
African swine fever (ASF) is a highly lethal and contagious disease of domestic and wild pigs.
David said symptoms of the disease can range from mild to severe.
"In its severe form, ASF can kill up to 100 per cent of the pigs it infects,” David said.
“ASF is not a threat to human health and the ASF virus cannot be transmitted from pigs to humans.”
Is there a vaccine for ASF?
After decades of research, David said promising ASF vaccines have been recently developed and commercialised in Vietnam.
"These vaccines contain one or more gene deletions to weaken the virus and are known as modified live virus vaccines," David said.
However, there are limitations with using these vaccines. The vaccines are currently only effective against one strain of the virus.
“Another disadvantage is that modified live virus vaccines have inherent safety issues, because they may revert to a disease-causing form under some circumstances," David said.
“Furthermore, the manufacturing process is complex, as is the handling and distribution of the vaccine.
“And these vaccines cannot be used in sows, or in pigs with underlying infections or illnesses because of possible side-effects.”
What would happen in an outbreak?
Currently Australia is free from African swine fever virus (ASFV).
This provides us with the ability to trade our livestock products with many countries, some who restrict imports from countries that have the virus.
“For Australia to continue trading, we must be able to provide evidence that we remain free from the virus," David said.
"If there were an outbreak of ASFV here, there would likely be an immediate stop to pork exports. We would implement measures to control the outbreak with the aim of eradicating the virus.
“To reestablish trading rights, we must again prove we are free of the disease.”
What is our solution to ASF?
David said the challenge is to develop a safe and effective vaccine against all ASFV strains that can be produced economically, at scale, and can be readily adopted by pig producers.
Our researchers at ACDP are working with US company MBF Therapeutics to evaluate its DNA vaccine candidate.
"MBF Therapeutics will provide us with an ASF vaccine candidate produced via their T-Max™ platform," David said.
"We will then investigate exactly how the pig immune system reacts to these candidate vaccines."
David said the T-Max™ platform is based on technology adapted from immunotherapeutic treatment of human cancer and aims to eliminate pathogens as they enter the body.
“This protects the animal from infection and prevents disease transmission between animals," he said.
The vaccine candidates produced using this platform target T-cells response in the immune system. T-cells are one of the important types of white blood cells of the immune system and play a central role in the adaptive immune response.
Will the vaccine be safe and effective?
“Our goal is to create a safe and effective vaccine that can be used in all stages of swine production, including sows, while preventing disease in individual animals and limiting transmission within the herd and environment,” David said.
“One of the advantages of the T-Max platform is that it can be designed to include markers that allow us to distinguish between vaccinated pigs and those that have been naturally infected.”
What other research are we doing on ASF?
CSIRO’s ACDP is a vital part of Australia’s preparedness for disease outbreaks. Its microbiologically and physically secure facilities allow teams to work safely with animal and zoonotic diseases while keeping them securely contained.
“With the launch of our Immune Resilience Future Science Platform, we have recently started several new projects focused on deepening our understanding of the ASFV and how the pig immune system responds," David said.
“Each project will utilise new and emerging technologies to help uncover new information about ASF."