by: Richelle Anne Buno | Pseudouridine
Since its first detection in the country in 2019, African Swine Fever (ASF) has become an immense, serious threat to the swine industry due to its high virulence, high mortality rate, and overall drastic socio-economic consequence. The rapid escalation of ASF outbreaks has triggered widespread concerns and is especially feared by smallholders and traditional pig farmers that predominate the Philippine swine industry.
Despite vigilant ASF surveillance, control, and preventive strategies by authorities, the increase in cases and onslaught of outbreaks is still highly evident.
As of October 2024, the Department of Agriculture - Bureau of Animal Industry (DA-BAI) reported that ASF has spread to 17 regions, 76 provinces, 1017 cities or municipalities, and 5,955 barangays. Due to the recent outbreaks of ASF in multiple provinces, on top of the disastrous effects of El Niño and other calamities, a decrease in the volume of hogs produced was reported by the Philippine Statistics Authority (PSA), from 422,718.73 metric tons (MT) in the second quarter of the year 2023 down to 422,064.15 MT in the same quarter of 2024. The reduction in domestic swine production has led to the ramping up of meat importation as local prices continue to rise.
These numbers provide an overview of the significant impact of ASF on the livelihood of our farmers and its lasting, detrimental effects on biodiversity and overall animal health and welfare—posing a looming threat to the country's future regarding food security.
What is ASF?
African Swine Fever (ASF) is an infectious disease caused by the African swine fever virus (ASFV), a DNA virus of the genus Asfivirus from the family Asfarviridae. Domestic and wild varieties of Sus scrofa are greatly susceptible to ASFV. The highly virulent strain, Genotype II of ASFV, mainly accounts for most disease outbreaks in Asia and Europe.
According to the World Organization for Animal Health (WOAH), the severity of ASF clinical syndromes may vary from peracute, acute, subacute to chronic, depending on the virulence of the viral strains. Highly virulent viruses, or ASFVs, that are in acute and peracute forms are characterized by very high fever and hemorrhages in the reticuloendothelial and have an almost 100% mortality rate. ASFV can be transmitted within herds via direct contact and indirectly by ingesting contaminated feed, swill, and garbage.
Current actions taken for ASF monitoring and surveillance
In 2019, DA-BAI issued several policies to support efforts to control and manage the spread of ASF in affected areas. These policies, such as the National Zoning and Movement Plan for ASF, are established for the zoning and compartmentalization of different administrative regions based on the common disease status.
As part of the nationwide biosecurity and surveillance program, the government has allotted funds to develop and mass-produce rapid test kits for more effective and efficient monitoring and surveillance of the virus across the country. The ASFV Nanogold Biosensor Rapid Test Kit, developed by Central Luzon State University, is a nucleic acid-based test and consists of built-in DNA extraction and molecular amplification process that uses loop-mediated isothermal amplification (LAMP) primers designed for the amplification of the P72 gene of ASFV.
Recent vaccine procurement and rollout
Despite worldwide efforts to develop safe and effective vaccines for ASF, none have been internationally approved. Despite this, the Philippine government has recently funded the procurement and controlled rollout of Vietnam-made AVAC ASF Live Vaccines amidst safety concerns—much to the scrutiny of local and global experts.
On August 30, 2024, DA-BAI kicked off the vaccination program in Lobo, Batangas, wherein 41 uninfected pigs were inoculated with the AVAC vaccine, part of the 600,000 doses of live vaccines that the government planned to distribute by the end of 2024. In recent reports, 6 out of 41 inoculated pigs died due to comorbidities, as claimed by the DA. Last October 8, 2024, BAI announced promising results of the 28-day post-vaccination of Lobo pigs, wherein the vaccinated hogs are said to be developing sufficient antibodies against ASF.
Controversies and challenges: what’s the future for ASF vaccines?
Local scientists, hog producers, and other industry stakeholders have been skeptical about the efficacy of the vaccines, with most concerns revolving around the active ingredient of the Vietnam-made AVAC vaccine. The vaccine was derived from a virus strain called ASFV-G-∆MGF, or ∆MGF for short. It is a freeze-dried attenuated vaccine that uses live viruses treated to weaken the virulence but retain its immunogenicity. However, these types of vaccines still pose threats of mutation and reversion to their viral form.
On the public notice issued by the USDA Animal and Plant Health Inspection Service (APHIS) on October 27, 2022, the ∆MGF was withdrawn from the select agent regulatory exclusions because apparently “it has evaluated new information and determined that they have the potential to pose a severe threat to animal health or animal products,” according to the US Department of Agriculture - Animal and Plant Health Inspection Service.
Doubts were also raised regarding the alleged monopolization of the ASF vaccine. KPP Powers Commodities Inc. partnered with AVAC Vietnam Joint Stock Company, giving the company exclusive rights for domestic distribution of the ASF vaccine, the only vaccine with government authorization for export and a duly approved Certificate of Product Registration from Vietnam.
After AVAC’s initial announcement regarding the importation and distribution of its vaccine to the country in October 2022, WOAH then released an official position statement of risks “from use of substandard vaccines,” as they “may not confer any protection against ASF and risks spreading vaccine viruses that could result in acute or chronic disease.” Though it is not explicitly stated that the distribution of AVAC vaccines was the reason for issuing said warnings, authorities must ensure that proper testing has been done and that precautions have been taken before its widespread use.
Regardless of the issues revolving around the efficacy of currently available vaccines in the country, the government should not solely rely on vaccination but should also be more stringent on the border and movement controls and other biosecurity measures, such as early diagnosis, strict quarantine protocols, and immediate response during outbreaks.
Parts of a well-designed vaccination program are comprehensive post-inoculation surveillance and exit strategies in case of out-of-control situations that can force the cessation of vaccination. For transparency and accessibility, necessary data should be made available to the public, and regular public consultations should be conducted.
The challenge of ASF cure and prevention is a huge concern for local and global public health sectors. With the development of potent vaccines such as AVAC, the future of swine industries and research can be properly safeguarded with proper scientific procedures and vaccine regulations for the benefit of all smallholders, hog raisers, and industry stakeholders.
SOURCES
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ASF Updates. (2024, October 2).
Department of Agriculture- Bureau of Animal Industry. https://www.bai.gov.ph/stakeholders?Rep=African%20Swine%20Fever
DA Press Office. (2024, August 30).
DA, BAI start controlled vaccine administration to combat African Swine Fever
spread. Department of Agriculture. https://www.da.gov.ph/da-bai-start-controlled-vaccine-administration-to-combat-african-swine-fever-spread/
DA Press Office. (2024, October 8).
BAI reports promising results 28 days post-ASF vaccination of Lobo pigs.
Department of Agriculture. https://www.da.gov.ph/bai-reports-promising-results-28-days-post-asf-vaccination-of-lobo-pigs/
Food and Agriculture Organization
of the United Nations. (2024, October 3). African swine fever (ASF)
situation update in Asia & Pacific. FAO. https://www.fao.org/animal-health/situation-updates/asf-in-asia-pacific
Notice of Withdrawal of Select
Agent Regulatory Exclusions for Two Strains of African Swine Fever Virus, 87 FR
65023. (2022, October 27). https://www.federalregister.gov/documents/2022/10/27/2022-23446/notice-of-withdrawal-of-select-agent-regulatory-exclusions-for-two-strains-of-african-swine-fever
Philippines to roll out unproven
swine fever vaccine. (2024, August 23). SciDev.Net. https://www.scidev.net/global/news/philippines-to-roll-out-unproven-swine-flu-vaccine/
World Organization for Animal
Health. (2021). African swine fever. WOAH. https://www.woah.org/app/uploads/2021/03/a-african-swine-fever-v2-0.pdf
World Organization for Animal Health. (2023, October 18). African swine fever: WOAH warns Veterinary Authorities and pig industry of risk from use of sub-standard vaccines. WOAH. https://www.woah.org/en/african-swine-fever-woah-warns-veterinary-authorities-and-pig-industry-of-risk-from-use-of-sub-standard-vaccines/
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