A recent study highlights potential vulnerabilities in the U.S.’s ability to detect and manage an African swine fever virus (ASFV) outbreak, focusing on sampling and laboratory capacity. The research, conducted by North Carolina State University, examined the challenges of testing and containment, particularly in regions with high concentrations of swine farms.
ASFV is a highly contagious disease among pigs, with a mortality rate reaching up to 100%. Pigs may not show symptoms before succumbing to the virus, allowing it to spread undetected. An ASFV outbreak could potentially cost the U.S. economy $80 billion.
“The key to managing an ASFV outbreak is in testing and containing the infection,” stated Jason Galvis from North Carolina State University. He noted that timely testing could be challenging in densely populated farm areas.
The model used in this study, called PigSpread, simulated both large and small outbreak scenarios using data from a densely populated swine state. It estimated a median of 27 outbreaks over 150 days. In these scenarios, blood and oral samples were required from pigs across more than 3,000 barns.
Sampling logistics pose significant challenges due to necessary precautions against spreading the disease between farms. Sample collectors must wait 72 hours between farm visits. Depending on the scenario size, the number of required sample collectors ranged from 136 to as many as 3,115.
Laboratory capacity also presents issues since only specific labs can process these samples. The daily lab processing limit was capped at 1,000 samples per day in the study area. Without pooling samples for initial testing, processing delays averaged 92 days but could extend up to five years under worst-case conditions.
Some mitigation strategies were identified: reducing sampler downtime from 72 to 24 hours and incorporating oral sampling alongside blood tests shortened collection times; pooling samples alleviated some lab pressures. However, further evaluation is needed for these approaches’ feasibility.
“While there are limitations to the model,” Galvis emphasized that improving current sampling strategies is crucial for preparedness before an actual outbreak occurs.
This work was published in Preventive Veterinary Medicine and supported by USDA’s Animal and Plant Health Inspection Service under award AP23VSSP0000C088. Co-first authors include NC State Ph.D. student Muhammed Satici along with Galvis; Gustavo Machado served as corresponding author with contributions from Abagael Sykes at NC State and Kathleen O’Hara and Lisa Rochette at USDA.
