CHOICES
A publication of AAEA
Livestock diseases in the United States followed the first introduction of cattle, horses, and small ruminants (Steele, 2008). The first recorded diseases included Texas Cattle Fever in the 1860s (USDA-NAL, n.d.a) and nine outbreaks of foot-and-mouth disease (FMD) between 1870 and 1929 (Peffer, 1962). The first zoonosis recorded in the United States was rabies in 1753 (Steele, 1975), which likely transferred from dogs to pigs, other domesticated livestock, and to humans (Baer, 2007). To combat diseases, a veterinary division of USDA was initiated and became the Bureau of Animal Industry in 1884 (USDA-NAL, n.d.b). In 1897, state, federal, and industry collaborators formed the United States Animal Health Association to ensure the interstate shipment of healthy animals and to develop plans to prevent and eradicate animal disease (Steele, 2008). Historically, eradication programs were carried out for specific diseases, including FMD, hog cholera, tuberculosis, brucellosis, and screw worm (NRC, 2005).
Today, the federal agency charged with the primary responsibility for overseeing disease initiatives for livestock and poultry is the U.S. Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS). USDA-APHIS works with state animal health agencies, animal health professionals, and a network of laboratories to establish effective diagnostic systems, to carry out continual inspection and surveillance, and to respond to unforeseen emergencies from disease incursions (NRC, 2005). Ports of entry, inspection, quarantine, and surveillance systems have been established to prevent the introduction and spread of unwanted livestock diseases.
In 2023, agriculture, food, and related industries contributed roughly $1.53 trillion, or 5.6% of U.S. gross domestic product (GDP), and provided about 10.4% of U.S. employment (USDA-FAS, 2023a). The output valueof farms contributed $222.3 billion or about 0.8% of U.S. GDP in 2023 (USDA-ERS, 2024). The United States exported nearly $175 billion in agricultural products in 2023, down from 2022, with animals and animal products accounting for 18% (USDA-FAS, 2024). Given the economic value of animals, a key question is whether sufficient resources have been allocated to efficiently utilize and to safeguard a changing animal health system. To put this in perspective, in 2017 the U.S. public expenditure on agriculture—including animal agriculture—was about 1% of total public expenditure, or about 0.13% of GDP.
The United States is a primary protein producer and supplier in the global market (Figure 1). Chicken production, the largest by volume, increased steadily, from nearly 16.8 million metric tons (MMT) in 2010 to 21.4 MMT in 2023, where it has outpaced beef and pork production. U.S. beef production slightly increased from 12 MMT to 12.4 MMT, while pork production moderately increased on average from 10.2 MMT to 12.5 MMT in 2023.
U.S. meat export patterns follow domestic production but also include geopolitical and disease responses. Chicken export quantities (Figure 2) were nearly three times as large as beef exports in most years considered. Chicken exports fell to a low of 2.9 MMT in 2015 during the HPAI outbreak, then recovered and have held at around 3.3 MMT since 2020 despite the HPAI event starting in 2022. Pork exports have generally grown over time. Beef exports have varied from approximately 1 MMT to 1.6 MMT with a general upward trend from 2010 to 2023.
Exports relative to domestic production vary by protein (Figure 3). Pork has the highest and the largest difference in export shares, ranging from 19% in 2010 to a high of 26% in 2020. The top five export destinations for U.S. pork are consistently Mexico, Japan, China, Canada, and South Korea. Mexico and Japan were the top importers until China increased pork imports to account for losses related to ASF detected in China in 2018.
Exports also comprise a relatively large share of U.S. chicken production, with export shares ranging from 16% to 20%, despite the drop following the 2015 HPAI event. Mexico is the dominant importer of U.S. chicken, outranking imports by the next largest trade partner by more than double in most years from 2010 to present. Other important importers of U.S. chicken are Cuba, Taiwan, China and Hong Kong, the Philippines, Canada, and Angola. Export shares for beef have remained relatively consistent, at 9% to 12% of domestic production from 2010 to present. The top importers of U.S. beef have been Japan, South Korea, Mexico, Canada, China, and Hong Kong.
The World Organization for Animal Health (WOAH, https://www.woah.org/en/what-we-do/animal-health-and-welfare/official-disease-status/) makes official freedom-from-disease declarations for six diseases: African horse sickness, bovine spongiform encephalopathy (BSE), classical swine fever (CSF), contagious bovine pleuropneumonia, FMD, and peste des petits ruminants (PPR). For all other diseases, freedom-from-disease declarations can be made at the country level, lifting movement restrictions and quarantines. However, trade partners make individual decisions to reopen trade, potentially requiring additional negotiations or documentation. This makes surveillance for proof of disease freedom more complicated in practice because each bilateral trading partner must recognize that declaration.
Generally, surveillance includes both active and passive elements. Active surveillance involves purposefully sampling at-risk species using scientifically determined sampling procedures (Gates, Earl and Enticott, 2021). Passive surveillance uses secondary sources of information, such as veterinarian records and packer inspections, or producers or veterinarians reporting abnormal death losses, triggering additional diagnostics depending on the species and any visible signs ofdisease. Producer reporting can be challenging due to uncertainty regarding disease symptoms, fear of consequences, mistrust of authority, lack of incentives for reporting, or uncertainty about what will happen after reporting (Gates, Earl, and Enticott, 2021).
Wildlife plays an important role in disease surveillance efforts. For reporting purposes, wildlife surveillance is considered passive. Wildlife populations may be sampled through hunter-kill sampling or catching and releasing healthy animals. In addition, wildlife mortality or morbidity events should be reported and samples may be submitted for animal disease testing. USDA-APHIS Wildlife Services began a national surveillance effort for highly pathogenic avian influenza (HPAI) among wild birds in 2006 in response to the involvement of wild birds in HPAI spread in Asia (Bevins et al., 2014). This risk-based approach to large-scale wild bird surveillance was implemented using standardized protocols and customized to the risks in a particular area. Bevins et al. (2014) reported that over the 5-year program, 283,434 samples were collected, primarily from hunter harvest or wildlife agency harvest birds or live birds (98%). The national wild bird surveillance program was discontinued in 2011 (Bevins et al., 2014); however, the U.S. National Surveillance Plan for Highly Pathogenic Avian Influenza in Wild Birds initiated in response to HPAI is an ongoing part of response surveillance (CEAH, 2023). Thelessons learned from prior wildlife surveillance programs were instrumental in increasing HPAI awareness during HPAI outbreaks in 2016, 2017, and 2022–2024.
Robust surveillance systems reduce disease spread and identify areas of heightened risk as well as provide assurance and transparency of disease control to international trading partners. The introduction or reemergence of a disease can lead to international trade disruptions through the application of sanitary (animal health or food safety related) trade bans. The World Trade Organization (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures set out guidelines and procedures for food, plant, and animal safety both during an event and on recovery. During a disease event, a country may restrict trade to prevent domestic disease infection of animals, plants, and people. However, these decisions are complicated by trade flow reliance, risk perceptions, and price sensitivities. Historically, these were national trade restrictions, which led to greater market and trade flow disruptions, often at a price disadvantage. However, starting in the mid 2000s, regionalized trade restrictions have been used to combat the negative effects of a pathogenic disease. For example, during the 2014–2015 U.S. HPAI event, importers that had greater confidence in the strict protocols in monitoring and surveillance were able to minimize market disruptions compared to those implementing stronger restrictions (Thompson, 2018). This confidence is built on trust in unified procedures and relationships between countries. The impact of regionalized trade bans will be discussed further in thesection on HPAI. With increasing globalization,countrywide bans may be limited in the future, but this can only be true with continued vigilance and confidence in the exporter’s surveillance and monitoring abilities.
Scant empirical evidence exists on this topic. Johnson et al. (2015) report that the likelihood and degree of an embargo on the home country is conditional on WOAH-listings and WTO trade rules, as well as trade agreements, current stocks of the good, market structure, political climate, and other factors. In all, importing countries tend not to relax trade embargoes in the same way as one another or uniformly over time; rather, trade embargoes vary according to bilateral or multilateral trade agreements, risk, characteristics of the disease, and political agendas (Morgan and Prakash, 2006; Park, Jin, and Bessler, 2008; Johnson et al., 2015). The interplay between surveillance and economic impacts of disease, especially trade, will be explored in a series of disease specific cases. These case descriptions are not intended to be all-inclusive, but rather to highlight the way animal diseases have challenged and changed the U.S. animal industry in various ways.
Since the turn of the century, several disease events have resulted in rapid advances in U.S. animal health prevention and management. BSE in 2003 not only resulted in large and long-lasting trade losses but also in permanent changes to processor practices. HPAI spread by wild bird populations to domestic poultry has occurred periodically, but large outbreaks occurred in 2014–2015 and 2022–2024. These outbreaks have tested and refined commercial, smallholder, and wild bird surveillance procedures and tested the capacity of the National Animal Health Laboratory Network (NAHLN). Virulent Newcastle disease (vNDV) spread largely in smallholder and exhibition bird flocks in 2018–2020, posing different surveillance challenges compared to HPAI. Porcine epidemic diarrhea virus (PEDv) was an emerging disease not on the WOAH notifiable disease list. The swine industry and private veterinarians led the on-farm response to PEDv with the federal government supporting response through diagnostics, analytics, epidemiologic studies, and data management (Scott et al., 2016).
These U.S. animal disease events are contrasted with influential FMD outbreaks elsewhere in the world. Although FMD has not been found in the United States since 1929, high-profile outbreaks in the UK, Brazil, and Japan have furthered unified global guidelines on foreign animal disease response. From 2005 to 2020, WOAH data indicated that FMD accounted for 94% of animal disease-related cattle deaths globally, African swine fever (ASF) accounted for 75% of swine deaths, and HPAI accounted for 97% of poultry deaths due to highly contagious animal diseases (Lwin, Schaefer, and Hagerman, 2024).
BSE is a fatal disease of the central nervous system in cattle, which has had significant impacts on international trade (Coffey et al., 2005). There are two forms of BSE: classical and atypical. Classical BSE has been found to spread through the feeding of meat and bone meal from inflected animals, as the standard treatment processes do not fully inactivate the prion (USDA-APHIS, 2024). Classical BSE was first detected in the UK in 1986 and has since been detected in 25 countries. This WOAH-listed disease has been linked to the variant Creutzfeldt-Jakob disease (vCJD) in humans since 1996 (Alarcon et al., 2023). According to Alarcon et al. (2023), there have been 183,325 BSE cases (including atypical cases) in cattle in the UK. In a report by National CJD Research and Surveillance Unit (2020), 178 human cases of vCJD were reported in the UK through 2020, with an annual human mortality of 1.98 cases/million in 2020. Atypical BSE can occur naturally in aging cows. Incidences of both forms of BSE in cattle and vCJD in humans continue to trend downward.
BSE resulted in permanent process changes for cow slaughter and surveillance at the packing plant. In response to the emergence of classical BSE cases in 1989 (WOAH, n.d.), the United States banned the importation of live ruminants and most ruminant products from BSE-infected countries in that year. Beginning in 1990, the United States initiated a BSE surveillance program by examining brain tissue from cattle showing clinical signs of a degenerative neurological disorder—commonly called “downer cows” in the instance of significant mobility issues—and samples from high-risk cattle (USDA-APHIS, 2024). The Food and Drug Administration (FDA) banned protein derived from mammalian tissue in feed for cattle in 1997 (USDA-APHIS, 2024).
Although the United States proactively tried to prevent the introduction of BSE, a single case was identified through ongoing surveillance in December 2003 in Washington State; the event is commonly called “the cow who stole Christmas.” Mathews, Vandeveer, and Gustafson (2006) describe the economic consequences from the 2003 BSE detection, including the immediate trade losses. The authors particularly note the importance of the current cattle markets and low beef inventories in allowing the cattle industry to absorb much of the trade loss without excessive impacts on consumers. In 2009, the FDA established an enhanced feed ban for high-risk tissue materials in all animal feeds and harmonized feed control measures in the United States with Canada (CDC, 2021). Since 2003, six additional atypical cases of BSE have been identified, with the last case announced in 2023. It took more than a decade to negotiate the release of the last of the BSE-related trade bans.
Returning to Figure 3, China and Hong Kong varied purchasing behavior after the U.S. BSE discovery in 2003. China banned U.S. beef imports until 2017, when imports were permitted with age limits. During the 14-year period of China’s restrictions, the United States was able to continue exporting beef to Hong Kong, which was likely destined largely for reexport to China despite the trade restrictions. The longtime trade restrictions imposed on U.S. beef by China contrasted with the regionalized restrictions imposed on U.S. poultry during recent HPAI events (Padilla, Baker, and MacLachlan, 2024) illustrate the importance of the severity of the disease, the shift in global trade policy response, and the response mechanisms in place to mitigate disease impacts when considering the effects on international trade.
Today, the USDA continues a monthly BSE surveillance program, sampling approximately 25,000 head of cattle annually (USDA-APHIS, 2024). The United States is recognized by WOAH as a negligible risk for BSE (WOAH, n.d.). The 2003 classical BSE case remains the only classical case in the United States to date, but enhanced surveillance and risk management are needed on an ongoing basis to quickly identify atypical BSE cases and protect U.S. export markets.
Porcine epidemic diarrhea virus is a coronavirus that causes high morbidity and mortality in piglets; it is highly contagious, spreading quickly through the fecal-oral route (Schulz and Tonsor, 2015). PEDv has been detected in countries across Europe and Asia dating back to 1971; however, it was first confirmed in the United States in 2013 and subsequently spread to Canada and Mexico in 2014. Although the pathway into the U.S. will likely never be known (Scott et al., 2016), the U.S. strains were found to be genetically similar to that of strains in China (Vlasova et al., 2014). PEDv was primarily spread by a direct or indirect fecal-oral route and entered farms through infected pigs, trailers (i.e., transporting pigs, feed, or manure), people (via contaminated clothing), and wild animals/birds. The symptoms of PEDv in swine include diarrhea, vomiting, dehydration, and death in 50%–100% of infected piglets (WOAH, 2014). Although mortality in older swine (e.g., feeders, sows) was low, almost all swine, regardless of age, experienced morbidity. During the approximate 1-year epidemic, it was estimated that 8 million newborn piglets died (Lee, 2015) and 50% of U.S. breeding herds were infected (Niederwerder and Hesse, 2018).
Schulz and Tonsor (2015) noted this PEDv outbreak was a supply-impacting disease with limited demand-driven loss, as PEDv is not zoonotic and is not a WOAH notifiable disease. U.S. pork exports were not subject to trade restrictions. With only reductions in the supply of hogs and no change in demand (domestic or foreign), the price of market hogs and pork would increase. These price increases would lead to higher returns to producers that were not directly impacted by PEDv (Schulz and Tonsor, 2015). Paarlberg (2014) estimated that hog producers gained $1.2 billion to $2.3 billion annually with a reduction of 3%–6% in the annual U.S. pig supply, respectively, while slaughter plants/processors returns would fall by $481 million to $929 million. Consumers would also experience economic welfare losses of between $300 million to $600 million from higher pork prices. PEDv is an instance where public investment in surveillance supported industry response. Producers were able to identify the prevalence of the disease and take appropriate risk management actions.
Avian influenza (AI) viruses are grouped by their H and N proteins and are further divided into HPAI and low pathogenic AI (LPAI). HPAI is highly contagious and often fatal to poultry and wild birds. LPAI occurs naturally in wild waterfowl without causing illness. HPAI was first documented in Italy in 1878 (Alexander and Brown, 2009). HPAI has also been found to cross over into mammalian species, namely 1,080 confirmed dairy cattle in 18 U.S. states since March 2024 (CDC, 2025). In addition to being highly contagious, HPAI has been known to cause cases of human infection (e.g., H7N9 and H5N1). Most recently, 70 people contracted H5 HPAI since 2024, with one human death (CDC, 2025).
The U.S. government has invested significant resources into preventing, managing, and eradicating HPAI from U.S. flocks, including developing the HPAI Response Plan—The Red Book. Mitigation and response plans have been implemented in almost every state, as have the Secure Egg/Turkey/Broiler Supply plans. One of the major challenges associated with HPAI is that the viruses circulate in migratory wild bird populations, creating opportunities for spillover into domestic poultry. Extensive wild bird surveillance systems have been implemented across all U.S. wild bird flyways, as discussed previously.
After the 2014-2015 HPAI event, highlighted in a 2016 Choices theme (https://www.choicesmagazine.org/choices-magazine/theme-articles/economic-consequences-of-highly-pathogenic-avian-influenza/theme-overview-economic-consequences-of-highly-pathogenic-avian-influenza), the USDA was able to address post-outbreak response improvements in control activities, indemnity and virus elimination payments, and the repopulation processes and timelines (USDA-APHIS, 2016). In addition, industries adapted practices in response to current outbreaks; for example, rapidly restocking layers rather than the gradual restocking process initially expected (Ramos, MacLachlan, and Melton, 2017). The experiences gained by producers created a capacity for response in future outbreaks; for example, increasing the number of depopulation and composting experts approved for use as government contractors. These updates to the response plan have not only resulted in differences in government response costs but have led to smaller international trade impacts and fewer supply chain effects on the poultry and egg industries (USDA-APHIS, 2022).
Regionalization terms under bilateral trade agreements and extensive surveillance to ensure that birds and eggs entering the food supply chain are HPAI-free have helped reduce economic damage. This is reflected in Figure 1 for exports of eggs and egg products and ofbroiler meat using Global Agricultural Trade System (GATS) data (USDA-FAS, 2023b). The vertical dashed lines from 2014 to 2015 show the sharp decline in egg exports, but especially in broiler meat exports. The 2014–2015 HPAI outbreak had very limited cases on broiler operations, yet international trade bans contributed to sharp declines in exports in 2015. While Russia had already banned U.S. poultry products for geopolitical reasons earlier in 2014, 18 foreign importing countries, including major poultry importers China and South Korea, imposed persistent national bans shortly after HPAI was first detected in December 2014 (MacLachlan, Boussios, and Hagerman, 2022).
The 2022 HPAI incursion differed from previous events in several ways. First, in 2015 the virus moved from west to east following migratory bird flyways. In 2022, the virus moved east to west and back across all major flyways, continuing through 2024. Second, investments in biosecurity and disease awareness campaigns among commercial poultry producers paid dividends. The 2015 event spread mechanism was predominantly laterally based (farm-to-farm), spreading from poultry house to poultry house. The 2022 event was driven by wild bird migrations resulting in independent introductions with limited lateral spread. By March 2023, HPAI had crossed 47 states driven primarily by wild bird migration (CEAH, 2023). This resulted in 499 infected commercial flocks from the start of the outbreak in 2022 to June 2024 (versus 211 in the 2014–2015 outbreak). However, the backyard poultry industry was more heavily involved in the 2022–2024 outbreaks; while HPAI was detected in just 21 backyard farms in 2014–2015, there were detections in 655 backyard flocks from 2022 to June2024. Information is readily available to backyard growers to encourage reporting which could account for some of this increase. Third, both outbreaks were H5 viruses, but the genetic differences allowed it to remain viable even in hot, dry conditions through the summer. Fourth and finally, as our understanding of HPAI and surveillance capabilities evolves, so has the geographic magnitude of trade embargoes. Several countries that implemented multistate or national trade embargoes in 2015 (Thompson, 2018) instead imposed county- or even zone-based trade embargoes in 2022 (Padilla, Baker, and MacLachlan, 2024). This is reflected in the differences in export changes shown in Figure 4 between the two outbreaks.
Virulent Newcastle disease (vNDV) is a highly contagious and fatal viral poultry disease, with clinical signs that can be respiratory, reproductive, intestinal, or neurological, and is a WOAH reportable disease (USDA-APHIS, 2021a). vNDV is spread through direct contact with a sick bird, and markets or exhibitions that result in mixing birds from many different premises such as live bird markets or poultry fairs create a high risk of spread, as highlighted in the most recent U.S. vNDV outbreak. It was initially detected in Southern California in May 2018 and was not fully under control until May 2020, impacting 476 confirmed premises in California, of which four were commercial, and two premises in Utah and Arizona (USDA-APHIS, 2021a). This outbreak led to movement restrictions and permitting for movement in and out of the quarantine area (USDA-APHIS, 2021a).
This event is unique in that it predominantly impacted backyard or noncommercial flocks. This led to greater demands by surveillance to identify infected premises when there may be competing incentives to report disease, requiring more personnel hours to identify, contact, and sample many different premises. An additional complication came from the possible role of illegal fighting birds in disease spread. If a person were to keep fighting cocks that were infected, they would have negative incentives to report the disease, increasing the viral load and potential for disease spread. State and federal surveillance teams had to assure responders they were not there for purposes other than animal health. In addition, the indemnification process does not value illegal activities, so fair market value would undervalue the potential losses for depopulation of an infected premises engaging in fighting exhibitions. The surveillance system can only work if there are the appropriate incentives to report a disease but not over incentivize and lead to increased disease occurrence from bad actors.
Another complicating aspect of this event was the mobility of backyard birds. The movement for legal and illegal purposes leads to increased infection spread and ultimately increase control and eradication costs. A USDA-APHIS epidemiological report highlighted the dangers of long-distance spread by movement of infected poultry or fomites and found that longer-distance transmission—such as the spread of vNDV to Utah and Arizona—were likely due to either undetected poultry or violations of the fallow period after detection (USDA-APHIS, 2021a). This emphasizes the value of the quarantine zones in minimizing disease spread. It also speaks to the vigilance of border states in surveilling for introduction of a disease.
FMD is a highly contagious viral disease of cloven-hoofed animals—such as bison, cattle, deer, goats, pigs, and sheep—that has a very high morbidity rate in most susceptible species with varying degrees of severity in clinical signs but a low mortality rate especially among adult animals (WOAH, 2023). FMD has significant economic impacts due to production losses and disruption to international trade (Paarlberg, Seitzinger, and Lee, 2007). Clinical signs that are consistent with FMD have been described since the 1500s, and the disease was first formally diagnosed in 1898 (Rahman et al., 2025). There are seven serotypes of FMD virus, with many more subtypes. According to WOAH (2010), over 100 countries are not considered FMD-free. FMD is endemic (or persistently recurring) in the susceptible livestock population in a large part of Africa and the Middle East and in parts of Asia. In the Western Hemisphere, FMD is endemic in parts of South America, with most countries recognized as FMD-free, with or without regionalization or vaccination (WOAH, 2010). Because the FMD virus is hardy and able to spread through multiple modes, the disease typically has stringent disease controls and can cause significant economic impacts. This is particularly true of trade impacts; when WOAH established the official disease-free territories list, FMD was the first disease on this list.
Due to the severity of FMD and the fact the United States, Canada, and Mexico have been FMD-free since 1929, 1952, and 1954, respectively, the United States has spent significant time, energy, and resources in undertaking preventative measures, developing and implementing surveillance strategies, planning and preparing for an outbreak, and creating a response plan (i.e., Foot-and-Mouth Disease Response Plan—The Red Book). The economic importance of maintaining disease-free status, and the ability to respond quickly and efficiently if FMD is detected, drives the United States to continue prioritizing efforts to safeguard the U.S. and North American livestock sectors from the disease. Prominent outbreaks in the UK (2001 and 2003), Brazil (2001 and 2005), Taiwan (1997), and Japan (2009) have highlighted lessons that influence U.S. FMD prevention, response, and surveillance plans.
The threat of FMD spurred a major public investment in foreign animal disease preparedness in 2018. The Agriculture Improvement Act of 2018 (commonly called the 2018 Farm Bill) invested in a National Animal Vaccine and Veterinary Countermeasures Bank, a new U.S.-only vaccine bank that allows stockpiling of vaccines in the event of an FMD outbreak or other foreign animal disease threat. The same bill invested in the capacity of the NAHLN, a network of federal, state, and university laboratories that provide detection capacity for major foreign animal disease threats. Finally, research and Extension efforts by universities, tribal governments, and nonprofit organizations were supported through the National Animal Health Preparedness and Response Program. In total, the U.S. Congress invested $120 million from 2019 through 2022, with $30 million available each year thereafter (P.L. 115-334, Section 12101). The continued investment in both preparedness against high-consequence foreign animal disease threats and response to active threats is driven both by the reliance on our own robust, safe food production system in the United States and also on the economic benefits of open access to international markets. The next sections will more fully explore U.S. meat production and exports, and how that has led to varying levels of risk exposure due to sanitary trade bans.
The rise and resurgence of important transboundary and zoonotic diseases will continue to drive efforts to improve monitoring and surveillance in U.S. animal production. A notable current example is the emergence of HPAI strains in dairy cattle in the United States. Over the past decade, improvements have enabled business continuity through regionalization and trust in the disease eradication and control process. Increased funding and targeted surveillance programs have led to earlier identification of disease threats, with policies in place for rapid response. Future challenges to these systems include increased globalization, urbanization, and budget allocation decisions. Diseases are dynamic threats, requiring adaptable and quickly deployable surveillance and eradication programs. While the United States has made progress since past events, these efforts must remain at the forefront to ensure a safe, healthy food supply for domestic and international markets.
115th U.S. Congress. 2018. Agriculture Improvement Act of 2018. P.L. 115-334. Section 12101 Animal Disease Prevention and Management, 449–454.
Alarcon, P., B. Wall, K. Barnes, M. Arnold, B. Rajanayagam, and J. Guitian. 2023. “Classical BSE in Great Britain: Review of Its Epidemic, Risk Factors, Policy and Impact.” Food Control 146:109490. https://doi.org/10.1016/j.foodcont.2022.109490
Alexander, D.J., and I.H. Brown. 2009. “History of Highly Pathogenic Avian Influenza.” Revue Scientifique et Technique (International Office of Epizootics) 28(1):19–38. https://doi.org/10.20506/rst.28.1.1856
Baer, G.M. 2007. “The History of Rabies.” In A.C. Jackson, ed. Rabies, 2nd ed. Academic Press, pp. 1–22.
Bevins, S.N., K. Pedersen, M.W. Lutman, J.A. Baroch, B.S. Schmit, D. Kohler, T. Gidlewski, D.L. Nolte, S.R. Swafford, and T.J. DeLiberto. 2014. “Large-Scale Avian Influenza Surveillance in Wild Birds Throughout the United States.” PLoS One 9(8):e104360. https://doi.org/10.1371/journal.pone.0104360
Black, N. 1996. Animal Health: A Century of Progress. United States Animal Health Association. Available online: https://www.usaha.org/upload/History/AnimalHealth_ACenturyOfProgress_.pdf
Centers for Disease Control (CDC). 2021. “Bovine Spongiform Encephalopathy (BSE).” Available online: https://www.cdc.gov/mad-cow/php/animal-health/index.html
———. 2024, May 22. “CDC Reports Second Human Case of H5 Bird Flu Tied to Dairy Cow Outbreak.” CDC Newsroom. Available online: https://www.cdc.gov/media/releases/2024/s0522-human-case-h5.html
———. 2025. H5 Bird Flu: Current Situation. Available at: H5 Bird Flu: Current Situation | Bird Flu | CDC. [Accessed September 2025]
Center for Epidemiology and Animal Health (CEAH). 2023. Epidemiologic and Other Analyses of HPAI-Affected Poultry Flocks: 1 June 2023 Interim Report. U.S. Department of Agriculture Animal and Plant Health Inspection Service. Available online: https://www.aphis.usda.gov/sites/default/files/epi-analyses-avian-flu-poultry-2nd-interim-rpt.pdf
Coffey, B., J. Mintert, J.A. Fox, T.C. Schroeder, and L. Valentin. 2005. The Economic Impact of BSE on the US Beef Industry: Product Value Losses, Regulatory Costs, and Consumer Reactions. Kansas State University Department of Agricultural Economics, prepared for the Kansas Department of Agriculture. Available online: https://agmanager.info/sites/default/files/EconomicImpactofBSEonUSBeefIndustry.pdf
Gates, M.C., L. Earl, and G. Enticott. 2021. “Factors Influencing the Performance of Voluntary Farmer Disease Reporting in Passive Surveillance Systems: A Scoping Review.” Preventive Veterinary Medicine 196:105487. https://doi.org/10.1016/j.prevetmed.2021.105487
Johnson, K.K., A.D. Hagerman, J.M. Thompson, and C. Kopral. 2015. “Factors Influencing Export Revenue Recovery after Highly Pathogenic Poultry Disease Outbreaks.” International Food and Agribusiness Management Review Special Issue: Factors Influencing the Global Poultry Trade 18(SIA):27–42. https://doi.org/10.22004/ag.econ.207000
Lee, C. 2015. “Porcine Epidemic Diarrhea Virus: An Emerging and Re-Emerging Epizootic Swine Virus.” Journal of Virology 12:193. https://doi.org/10.1186/s12985-015-0421-2
Lwin, W.Y., K.A. Schaefer, and A.D. Hagerman. 2024. “Animal Disease Outbreaks and Upstream Soybean Trade.” Food Policy 127:102685. https://doi.org/10.1016/j.foodpol.2024.102685
Mathews, K., M. Vandeveer, and R.A. Gustafson. 2006. An Economic Chronology of Bovine Spongiform Encephalopathy in North America. USDA Economic Research Service Outlook Report LDP-M-143-01.
Morgan, N., and A. Prakash. 2006. “International Livestock Markets and the Impact of Animal Disease.” Revue Scientifique et Technique de OIE 25(2): 517–528. ISSN (Print): 0253-1933
National CJD Research & Surveillance Unit. 2020. The 29th Annual Report 2020 Creutzfeldt-Jakob Disease Surveillance in the UK. Available online: https://cjd.ed.ac.uk/sites/default/files/2024-12/Twenty-Ninth Annual Report 2020.pdf
National Research Council (NRC). 2005. Animal Health at the Crossroads: Preventing, Detecting, and Diagnosing Animal Diseases. National Academies Press. https://doi.org/10.17226/11365
Niederwerder, M.C., and R.A. Hesse. 2018. “Swine Enteric Coronavirus Disease: A Review of 4 Years with Porcine Epidemic Diarrhoea Virus and Porcine Deltacoronavirus in the United States and Canada.” Transboundary and Emerging Diseases 65(3):660–675. https://doi.org/10.1111/tbed.12823
Paarlberg, P.L. 2014. “Updated Estimated Economic Welfare Impacts of Porcine Epidemic Diarrhea Virus (PEDV).” Working paper. Purdue University Department of Agricultural Economics. Available online: https://econpapers.repec.org/paper/paewpaper/14-4.htm
Paarlberg, P.L., A.H. Seitzinger, and J.G. Lee. 2007. “Economic Impacts of Regionalization of a Highly Pathogenic Avian Influenza Outbreak in the United States.” Journal of Agricultural and Applied Economics 39(2):325–333. https://doi.org/10.1017/S1074070800023026
Padilla, S., Q. Baker, and M. MacLachlan. 2024. “Impacts of HPAI Trade Restrictions on U.S. Poultry Exports in 2022-2023.” Applied Economic Perspectives and Policies 47(3):933-948. https://doi.org/10.1002/aepp.13504
Park, M., Y. Jin, and D.A. Bessler. 2008. “The Impacts of Animal Disease Crises on the Korean Meat Market.” Agricultural Economics 39(2):183–195. https://doi.org/10.1111/j.1574-0862.2008.00325.x
Peffer, E.L. 1962. “Foot-and-Mouth Disease in United States Policy.” Food Research Institute Studies 3(2): 141–180. https://doi.org/10.22004/ag.econ.136621
Schulz, L.L., and G.T. Tonsor. 2015. “Assessment of the Economic Impacts of Porcine Epidemic Diarrhea Virus in the United States.” Journal of Animal Science 93(11):5111–5118. https://doi.org/10.2527/jas.2015-9136
Ramos, S., M. MacLachlan, and A. Melton. 2017. “Impacts of the 2014-2015 Highly Pathogenic Avian Influenza Outbreak on the U.S. Poultry Sector.” USDA Economic Research Service, LDPM-282-02.
Scott, A., B. McCluskey, M. Brown-Reid, D. Grear, P. Pitcher, G. Ramos, D. Spencer, and A. Singrey. 2016. “Porcine Epidemic Diarrhea Virus Introduction into the United States: Root Cause Investigation.” Preventive Veterinary Medicine 123:192–201.https://doi.org/10.1016/j.prevetmed.2015.11.013 https://doi.org/10.1016/j.prevetmed.2015.11.013
Steele J.H. 1975. “History of Rabies.” In G. Baer, ed. Rabies, Vol. 1. Academic Press
———. 1991. “History of Veterinary Public Health in the United States of America.” Revue Scientifique Et Technique de OIE 10(4):951–983. https://doi.org/10.20506/rst.10.4.582
———. 2008. “Veterinary Public Health: Past Success, New Opportunities.” Preventive Veterinary Medicine 86(3–4):224–243. https://doi.org/10.1016/j.prevetmed.2008.02.014
Thompson, J.M. 2018. “Effects of Regionalized Trade Restrictions on Quantity Exported During a Highly Pathogenic Avian Influenza Event.” Journal of Agricultural and Applied Economics 50(2):270–289. https://doi.org/10.1017/aae.2017.29
U.S. Department of Agriculture, Animal and Plant Health Inspection Service (USDA-APHIS). 2016. Final Report for the 2014-2015 Outbreak of Highly Pathogenic Avian Influenza in the United States. Available online: https://www.aphis.usda.gov/media/document/2086/file
———. 2021a. Epidemiologic Analyses of Virulent Newcastle Disease in Poultry in California March 2021. USDA-APHIS Veterinary Services Center for Epidemiology and Animal Health. Available online: https://www.aphis.usda.gov/sites/default/files/epi-analy-vnd-poultry-calif.pdf
———. 2021b. Epidemiologic Analyses of Virulent Newcastle Disease in Poultry in California, March 2021. USDA-APHIS Veterinary Services Center for Epidemiology and Animal Health. Available online: https://www.aphis.usda.gov/sites/default/files/epi-analy-vnd-poultry-calif.pdf
———. 2022. Epidemiologic and Other Analyses of HPAI Affected Poultry Flocks July 2022 Interim Report. USDA-APHIS Veterinary Services Center for Epidemiology and Animal Health. Available online: https://www.aphis.usda.gov/sites/default/files/epi-analyses-hpai-poultry-july2022.pdf
———. 2024. “BSE Ongoing Monthly Surveillance Program.” USDA-APHIS Veterinary Services. Available online: https://www.aphis.usda.gov/veterinary-services/bse-ongoing-monthly-surveillance-program [Accessed June 2024]
U.S. Department of Agriculture Economic Research Service (USDA-ERS). 2024. “Agricultural Trade.” Available online: https://www.ers.usda.gov/data-products/ag-and-food-statistics-charting-the-essentials/agricultural-trade [Accessed June 2024]
U.S. Department of Agriculture Foreign Agricultural Service (USDA-FAS). 2023a. Production, Supply, and Distribution Database. Available online: https://apps.fas.usda.gov/psdonline/ [Accessed June 2024]
———. 2023b. “U.S. Trade Export Data.” Global Agricultural Trade System (GATS) [database]. Available online: https://apps.fas.usda.gov/gats/default.aspx [Accessed January 2024]
———. 2024. 2023 United States Agricultural Export Yearbook. Available online: https://www.fas.usda.gov/data/2023-us-agricultural-export-yearbook [Accessed June 2024]
U.S. Department of Agriculture National Agricultural Library (USDA-NAL). n.d.a. “Texas Cattle Fever.” USDA-NAL Special Collections: USDA’s Contributions to Parasitology. Available online: https://www.nal.usda.gov/exhibits/speccoll/exhibits/show/parasitic-diseases-with-econom/parasitic-diseases-with-econom/texas-cattle-fever/
———. n.d.b. “The U.S. National Animal Parasite Collection Records.” USDA-NAL Special Collections at the Library. Available online: https://www.nal.usda.gov/collections/special-collections/us-national-animal-parasite-collection-records [Accessed June 2024]
Vlasova, A.N., D. Marthaler, Q. Wang, M.R. Culhane, K. Rossow, A. Rovira, J. Collins, and K. Jung. 2014. “Distinct Characteristics and Complex Evolution of PEDV Strains, North America, May 2013–February 2014”. Emerging Infectious Diseases 20(10):1620–1628. https://doi.org/10.3201/eid2010.140491
World Organization for Animal Health (WOAH). 2023. “Foot-and-Mouth Disease (FMD).” Available online: https://www.woah.org/en/disease/foot-and-mouth-disease/
———. 2010. “Foot and Mouth Disease Questions and Answers.” Available online: https://www.woah.org/en/disease/foot-and-mouth-disease/#ui-id-1 (Accessed September 2025).
———. n.d. “Bovine Spongiform Encephalopathy (BSE).” Available online: https://www.woah.org/en/disease/bovine-spongiform-encephalopathy/
