A study led by researchers at North Carolina State University utilized a computer model known as PigSpread to evaluate the potential spread and implications of African swine fever (ASF) within pig farms across the southeastern U.S. The findings indicated that movements between farms were the main method of transmission, and while existing control strategies could cut secondary infections by up to 79%, a significant outbreak could nonetheless ensue, leading to considerable financial implications.
ASF is an extremely infectious viral disease in pigs, potentially resulting in a mortality rate of 100%. An added challenge is the absence of symptoms in infected pigs before they succumb to the disease, which could lead to unnoticed virus spread. The economic fallout from a potential ASF outbreak in the U.S. could reach up to $80 billion.
To analyze the possible spread patterns of an ASF outbreak in the southeastern U.S., the researchers employed the PigSpread model. This epidemiological model examines six transmission paths, including movements of pigs between farms, vehicular movements, and local spread.
Data used in the model, including location, production type, capacity, between-farm swine movements, and vehicle movement data, were derived from the Morrison Swine Health Monitoring Project and information provided by cooperative swine production companies. This data related to 2,294 pig farms in the southeastern U.S.
The team ran approximately 230,000 simulations, each over a period of 140 days, considering scenarios both with and without control measures. They then calculated the average results from these simulations.
The model identified that movements between farms were responsible for 71% of disease transmissions, with local and vehicular spread each contributing roughly 14%.
Gustavo Machado, Assistant Professor of Population Health and Pathobiology at NC State, and the lead author of the study, explained, “While farm-to-farm animal movement is the primary transmission route, vehicular transmission and local spread also play significant roles in an outbreak.”
In the model, control actions, including quarantine, depopulation, movement restrictions, contact tracing, and enhanced surveillance, were shown to be effective. In simulations where these measures were enforced, secondary infections reduced by up to 79% within the 140-day period. Around 29% of simulations implementing all control strategies saw no new cases within that period.
Despite these promising findings, Machado cautioned, “The model results are slightly optimistic. While it shows the effectiveness of current strategies, it’s crucial to further explore this situation to determine the exact requirements for controlling an outbreak. Even with these interventions, an epidemic would likely persist beyond 140 days.”
The study, titled “Estimating the effectiveness of control actions on African swine fever transmission in commercial swine populations in the United States,” was published in Preventive Veterinary Medicine on June 12, 2023. It was supported by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service and the Swine Health Information Center-funded Morrison Swine Health Monitoring Project.
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Frequently Asked Questions (FAQs) about African Swine Fever control measures
What was the purpose of the study conducted by North Carolina State University researchers?
The study aimed to understand the potential spread of African swine fever (ASF) among pig farms in the southeastern U.S. using a computer model called PigSpread. The research also assessed the efficacy of current response strategies to an ASF outbreak.
What is African swine fever and why is it a concern?
African swine fever is an extremely infectious viral disease in pigs, potentially leading to a mortality rate of 100%. A significant concern is that infected pigs may not show any symptoms before death, thereby increasing the chances of undetected virus spread. The financial implications of an ASF outbreak in the U.S. could amount to up to $80 billion.
How was the potential spread of ASF evaluated in the study?
The researchers utilized the PigSpread model, an epidemiological tool, to analyze the different ways a potential ASF outbreak in the southeastern U.S. could develop. This model evaluates six transmission routes, including between-farm swine movements, vehicle movements, and local spread.
What were the key findings of the study?
The study found that between-farm movements were the main route of ASF transmission, accounting for 71% of disease spread. Existing control measures, such as quarantine, depopulation, movement restrictions, contact tracing, and enhanced surveillance, could reduce secondary infections by up to 79% but couldn’t entirely prevent an outbreak.
What are the implications of these findings?
The findings indicate the potential severity of an ASF outbreak in the U.S. and underscore the necessity of effective control measures. However, despite the positive impact of current control strategies, an outbreak could persist, resulting in significant economic costs. Therefore, further research is required to determine the precise requirements for managing such an outbreak.
More about African Swine Fever control measures
- African Swine Fever
- Understanding ASF and its Transmission
- The Morrison Swine Health Monitoring Project
- USDA’s Animal and Plant Health Inspection Service
- Preventive Veterinary Medicine Journal
5 comments
Quarantine, depopulation, movement restrictions, these are tough measures. But I guess if it stops the spread, its necessary… Stay safe, everyone.
Woah, ASF is really scary stuff… Especially the fact that pigs might not show symptoms until its too late. Hope we can get better at controling it.
the fact that current measures could cut secondary infections by up to 79% is promising. But we definitely need to continue research in this area!
i’m worried about the possible $80 billion fallout! That’s a lot of money. More research and prevention measures are needed for sure.
Didn’t know much about ASF before, but after reading this I think there’s definitely cause for concern. Hopefully we won’t have an outbreak, and if we do, we’re ready for it.