#DiscoverWithVSU: Study pinpoints factors linked to ASF outbreaks in Leyte pig farms

For many families in Leyte, raising pigs is more than a livelihood. It helps put food on the table, pay school expenses, and provide a source of income during difficult times. When African Swine Fever (ASF) reached Leyte, the effects were felt not only by pig raisers but also by the communities that depend on the swine industry. 

A newly published study has now provided a clearer picture of the conditions and practices associated with ASF outbreaks among pig farms in Leyte and Southern Leyte. It offers information that could help farmers and animal health authorities reduce future risks.

The study, entitled “Farm-level Risk Factors and Post-outbreak Perceptions of African Swine Fever among Pig Raisers on Leyte Island, Philippines: A Case-Control Study,” was published in the international peer-reviewed journal, Preventive Veterinary Medicine (Volume 254, 2026).

The research was conducted by Dr. Harvie P. Portugaliza and Dr. Christian Joseph C. de los Reyes of the Visayas State University Faculty of Veterinary Medicine (VSU FVM), in collaboration with Dr. Romeo S. Gundran and Dr. Roderick T. Salvador of Central Luzon State University. Drs. Portugaliza, Gundran, and Salvador are also members of the Philippine College of Veterinary Epidemiologists.

ASF is one of the most serious diseases affecting pigs worldwide. Although it does not infect humans, it spreads rapidly among swine populations and can cause severe economic losses. Since its entry into the Philippines in 2019, ASF has disrupted pork production in many areas and affected thousands of backyard and commercial pig raisers.

To better understand the disease in the local setting, the researchers studied 204 pig farms across Leyte and Southern Leyte, including 42 farms that tested positive for ASF and 162 farms that remained free of the disease. Information was gathered through interviews, farm visits, and on-site observations.

Findings revealed several factors associated with a higher likelihood of ASF outbreaks. Farms with more than average of 12 pigs were found to be at greater risk than smaller operations. Pig farms located near bodies of water also showed higher chances of infection. Another factor observed was the presence of birds that could freely enter pig pens, potentially contributing to disease transmission. 

The study found that farms where owners lived within the premises were more likely to experience ASF outbreaks, possibly because of the increased movement of people and materials between farms and surrounding communities.

The research identified practices that appeared to lower the risk of infection. Farms that treated their water through chlorination and those that required visitors to notify owners before entering showed lower odds of ASF occurrence. These are relatively simple measures that can be adopted by many backyard pig raisers without major investments.

Beyond farm management practices, the study examined how ASF affected the lives of pig raisers after outbreaks occurred.

More than half of the respondents reported losing income because of ASF-related restrictions, culling activities, reduced market opportunities, and declining pig prices. Many farmers said they changed the way they managed their farms after experiencing outbreaks, particularly by limiting visitors and paying closer attention to sanitation measures.

The researchers recommend strengthening biosecurity practices at the community level, improving farmer education programs, encouraging timely disease reporting, and providing support mechanisms for affected raisers. These measures could help reduce the impact of future outbreaks while supporting the long-term recovery of the swine industry.

Funded by the Department of Science and Technology–National Research Council of the Philippines (DOST-NRCP), the study adds to the growing body of Philippine research on African Swine Fever and provides locally generated evidence that can guide government agencies, local government units, veterinarians, and farming communities in developing more responsive disease-control strategies.

As the country continues to address the challenges posed by ASF, studies such as this demonstrate how research can help identify practical solutions grounded in local conditions  that ultimately benefit farmers, rural communities, and the agricultural sector as a whole.

This article is aligned with the Sustainable Development Goal (SDG) 2: Zero Hunger; SDG 3: Good Health and Well-being; SDG 8: Decent Work and Economic Growth; SDG 12: Responsible Consumption and Production, and; SDG 15: Life on Land. 

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