Every day, pigs across the United States experience illnesses that share many clinical signs with two foreign animal diseases: African swine fever and classical swine fever. If either disease were introduced into the United States, it would cause far-reaching losses to the industry. The challenge is that ASF and CSF can look indistinguishable from porcine reproductive and respiratory syndrome and other endemic swine diseases. Thus, even when an illness in our swine isn’t likely to be a FAD, a diagnostic test is necessary to confirm. Fortunately for U.S. swine producers, USDA operates a laboratory surveillance component with the specific goal of ruling out ASF and CSF in sick pigs.

The sick pig veterinary diagnostic laboratory component is one part of USDA’s larger surveillance efforts to demonstrate freedom from ASF and CSF in the United States, and to detect these diseases if they were to enter our country. Laboratory submissions from sick pigs are tested for ASF/CSF under USDA’s surveillance program when they are sent to approved VDLs, have reported clinical signs consistent with ASF/CSF, and include an approved sample type (spleen, spleen pulp swabs, lymph nodes, tonsils, whole blood, or whole blood swabs).

“USDA’s Swine Hemorrhagic Fevers Integrated Surveillance Plan is designed to sample a range of U.S. swine populations. In addition to the sick pig VDL component, the plan also targets slaughter and market hogs, swine from higher-risk operations and feral swine,” said a representative from USDA’s Swine Health Commodity Team.

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How can you take advantage of this program?

Producers from all types and sizes of swine operations, including show and non-commercial herds, are encouraged to keep the sick pig component in mind when experiencing disease outbreaks. ASF/CSF testing is funded by USDA and is done at no cost to producers or veterinarians. Swine producers and herd veterinarians are the first line of defense to protect our nation’s pigs from disease, and early detection puts the United States in a better position to respond to an incursion. To help the U.S.’s efforts to detect a potential ASF or CSF introduction early, consider following these steps:

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No further action is required after you submit the sample. Laboratory staff will evaluate the case and conduct ASF/CSF diagnostic testing if appropriate. This component provides an extra level of protection and assurance that routine sick pig cases are not ASF/CSF, at no cost to veterinarians or producers. Even negative results help the country, through the ongoing demonstration of disease freedom and associated confidence of trading partners in the health and quality of U.S. swine commodities.

If you ever strongly suspect ASF or CSF, contact your State Animal Health Official immediately for a FAD investigation.

Analyzing VDL data

Supported by the USDA Center for Epidemiology and Animal Health (USDA-CEAH), Rachel Schambow and her team at the University of Minnesota Center for Animal Health and Food Safety (UMN-CAHFS) examined the sick pig component’s implementation at two of the leading swine diagnostic labs in the country, the University of Minnesota VDL and the Iowa State University VDL. Using de-identified data from 2022-2024, they compared characteristics of cases tested through the sick pig VDL component to those that were not incorporated into the program, with the goal of identifying important differences.

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The analysis indicated that both labs are implementing the program at a high level. Together, they ruled out ASF/CSF in over 8,000 cases from 39 states during the study period. A total of 88% of cases with a compatible tissue at UMN and 63% at ISU were tested. As expected, the majority of submissions came from swine-dense states. Submissions from other states, particularly in the Northeast, were low. The vast majority of tissue cases came from nursery and finishing pigs, consistent with the industry population.

When analyzed further, submissions from pigs under one year of age were almost twice as likely to be tested for ASF/CSF compared to samples from older pigs. While potential opportunities for improvement exist, the sick pig VDL component appears to be efficiently ruling out ASF/CSF in sick pigs from commercial U.S. swine herds.