Foot-and-mouth disease virus (FMDV) remains uncontrolled in most of the world. North America is among the few “FMDV-free without vaccination” areas of the world. In the event of an FMDV outbreak in North America, effective control and elimination will require rapid detection. And rapid detection will rely on an efficient surveillance sampling technology and immediate access to accurate diagnostic assays. Consequently, the Swine Health Information Center (SHIC) funded a project at Iowa State University with the long-term objective of creating an FMD 3ABC antibody indirect ELISA (iELISA) for use with swine oral fluids.
In this study, prototype serum and oral fluid FMDV 3ABC ELISAs were developed using samples from animals of precisely known FMDV status. The optimized tests detected specific antibody in serum and oral fluid samples from FMDV-infected or FMDV-vaccinated pigs by seven to 14 days post exposure. Importantly, the response is not serotype specific, meaning, the 3ABC ELISAs detect antibody in animals exposed to serotypes O, A, SAT2, and Asia 1. Also, the assays detect antibody against a non-structural protein which is not present in FMDV inactivated vaccines, consequently, the test provides for differentiation of vaccinated vs infected animals (DIVA).
Diagnostic testing of swine oral fluid samples has proven to be an effective and reliable method for the surveillance of endemic infectious diseases. Expanding this methodology to include FMDV will help provide FMDV-infected countries a new tool to control the infection and prepare the US industry for a “worst-case” scenario.
The Swine Health Information Center’s (SHIC’s) efforts relating to monitoring, analysis, preparedness, and response to emerging diseases, domestic and foreign, are more essential than ever. The organization’s key priorities remain protecting and enhancing the health of the US swine herd. At the same time, the question is being asked, “What if an emerging disease from outside the US hits the US?” as producers observe what’s happening overseas. In SHIC’s 2018 Progress Report, delivered to the National Pork Board and approved on January 8, 2018, the organization’s efforts on behalf of the US pork industry, including working with the other industry’s organizations on African swine fever prevention, were detailed. An executive summary of the report is available here.
Key Preparedness Activities
SHIC published Polymerase Chain Reaction (PCR) Assay Catalog in 2018. The catalog provides diagnosticians with swine health case submissions pertinent information about the 17 new PCR (virus detection) tests funded by SHIC, including contact information of the experts for questions about availability and use. In 2018, research continued to fill in identified preparedness gaps for SHIC Viral Disease Matrix priority pathogens. Information on all SHIC-funded and directed work for PCR tests in 2018 is included in the Progress Report. To compliment SHIC’s Viral Disease Matrix, a Bacterial Disease Matrix was also developed and published in 2018.
Monitoring and Mitigating Risks
In 2018, regular publication of both Domestic and Global Swine Disease Reports began. Funded by SHIC and created in collaboration with leading universities, these reports provide near real-time information on disease diagnosis and movement. SHIC also worked with collaborators on feed-related issues, examining risks pertaining to pathogen transmission as well as mitigation. Collaborative work with other industry organizations resulted in the development of seven feed safety questions for producers to ask their suppliers. SHIC is also working with other groups to monitor consistency of international traveler screening processes by US Custom and Border Patrol, providing information to the agency when gaps are reported as a safeguard to the US herd.
Swine Health Information Projects
Review and updating of SHIC’s disease fact sheets was ongoing in 2018, providing refreshed information available on the organization’s website. SHIC also continued work with the Morrison Swine Health Monitoring project. Review of the National Poultry Improvement Plan and its potential for being adapted to the US pork industry is ongoing. And SHIC conducted a meeting of swine information sharing project coordinators for better results for the industry.
Surveillance and Discovery of Emerging Disease
SHIC’s diagnostic funding assistance program provided resources for diagnostic work related to a hemorrhagic tracheitis syndrome in Canada. Monitoring an ongoing SVA outbreak in Brazil as well as well as surveillance system research are other current priorities.
Responding to Emerging Disease
SHIC Rapid Response Teams were activated in 2018, investigating a PEDv outbreak domestically. The work was beneficial for discovery of the virus’s pathway onto the farms as well as for review and improvement of the Program itself.
For detail on these and more projects, review the full SHIC 2018 Progress Report.
SHIC began operation as a 501(c)(3) corporation on July 4, 2015. The organization’s mission is to protect and enhance the health of the United States swine herd through coordinated global disease monitoring, targeted research investments that minimize the impact of future disease threats and analysis of swine health data.
The National Pork Board, National Pork Producers Council and the American Association of Swine Veterinarians have each appointed two representatives to the SHIC Board of Directors. Three at-large producer representatives are also members of the Board. A Monitoring and Analysis Working Group and a Preparedness and Response Working Group have been formed to provide program oversight and decision-making. Each are actively meeting to fulfill their respective objectives.
Proactive mitigation of high-risk pathogens in feed with feed additives could be a way for us to protect North American herds from porcine epidemic diarrhea virus (PEDV), porcine reproductive and respiratory syndrome (PRRS), as well as foreign animal disease. The Swine Health Information Center sponsored research to investigate feed additives with potential to function as cost-effective mitigants. Action based on scientific knowledge is within closer reach, thanks to Drs. Diego G. Diel of South Dakota State University and Scott Dee of Pipestone Applied Research. In their study, a select group of additives, though none completely inactivating viruses, did show promising efficacy against high-risk pathogens potentially in feed. Investigators envisioned and studied potential mitigation periods prior to embarking to the US or upon arrival at the mill and worked with AFIA to select candidate mitigants.
Based on the outcome of previous feed survival studies, investigators selected highest risk combinations of viruses and ingredients for testing.
|Virus Tested||Surrogate Virus||Feed Ingredients Tested|
|Senecavirus A||Foot and Mouth Disease||Soybean meal, lysine. choline and vitamin D|
|PEDV||N/A||Soybean meal, lysine, choline, vitamin D|
|PRRSV||N/A||Soybean meal, DDGS|
|Bovine herpesvirus type 1||Pseudorabies Virus||Soybean meal, soy oil cake|
Although none of the feed additives tested completely inactivated the pathogens, reductions in viral titers on all pathogens studied were observed with mitigants containing various medium chain fatty acid blends, such as Captisure from Kemin as well as Kansas State University), organic acid mixtures (such as Activate DA from Novus) or formaldehyde plus propionic acid (SalCURB, Kemin). These results demonstrate that specific feed additives have the potential to reduce viral contamination levels in feed. Investigators suggest that further studies to assess mitigator mechanism of action are warranted. In addition, assessing the efficacy of these mitigants in pigs following natural feed consumption of contaminated and mitigated feed in conjunction with viral load and product inclusion rate is planned or underway
Chemical mitigation of feed alone may not be able to prevent potential transmission of pathogens through feed. Storage time and importation of feed ingredients from known and trustable sources should be considered and utilized to safeguard the US swine industry from unwanted viral pathogens endemic in other regions of the world.
In August 2015, a new, national outbreak of Seneca Valley A (SVA) began in the US, just one month after the Swine Health Information Center (SHIC) started operations. Looking back, we discovered Brazil had gone through an SVA outbreak during the late fall and winter of 2014-15 in the US, during their summer season, preceding the US occurrence. Thank you to Dr. Daniel Linhares of Iowa State University for notifying SHIC of this new SVA outbreak in Brazil and to Dr. Gustavo Simao, Agroceres PIC in Brazil, for offering this on-the-ground update of the current situation.
New Seneca Valley Virus A (SVA) outbreak in Brazil
Gustavo M R Simão
Veterinary Services Manager
In the past two months, some pig slaughterhouses in Brazil, located in the states of São Paulo, Goiás, Paraná, Santa Catarina and Rio Grande do Sul, have had their slaughter schedules temporarily suspended by the government’s Official Inspection Service, due to vesicular lesions. According to the current legislation in Brazil, all clinical cases with vesicular lesions, either in farms or slaughterhouses, must be immediately communicated to animal health authorities, because, until proven otherwise, FMD must be primarily considered. The shutdown of meat packing units and farms lasts three days on average, until negative serological results (ELISA test) are verified for the samples submitted to the National Agriculture and Livestock Laboratory (LANAGRO). In the first few weeks of the investigation, samples were also screened (ELISA test) for vesicular stomatitis (VS) and SVA as a differential diagnosis at LANAGRO. For SVA, all samples were negative, and for VS, there were a few positive cases on some of the initial screening serology, but the diagnosis was not confirmed.
Initially, most of the cases occurred at finishing sites, moving to nurseries and finally, farrowing sites (smallest number of cases). The vesicular lesions were usually very severe, such as completely detached hooves, and healing was delayed, sometimes taking more than 10 weeks. There are reports of farrowing sites with suckling piglet mortality rates approaching 30 percent.
Approximately four weeks after the first reports and with an increasing number of cases all over the country, the Official Animal Health Service was instructed by the Ministry of Agriculture (MAPA) to collect samples of not just serum but also vesicular fluid and affected skin at suspected farms. PCR screening for VS and SVA was initiated, with positive results for SVA and negative for VS. Also, other laboratories (non-official) and universities received samples from the same inspected farms and had the same positive results for SVA. The virus was also found through PCR tests in feed mill supplies such as mixed meat and bone meal, soybean mean and feed for finishing pigs at the farm.
The affected farms are being instructed to immediately block the entry of animals for at least six weeks, and mass exposure of the entire herd using feces of piglets with diarrhea (farrowing sites), and/or oral fluids collected from animals with snout lesions.
RNA samples extracted from the vesicular fluid will be sequenced in an attempt to elucidate the similarities between the current SVA and the virus from the 2014-2015 outbreak. However, one question that is still open is whether there is a new mutant SVA circulating in Brazil, with greater pathogenicity, or if this was just a fall in immunity of the Brazilian herd after these three years between the two outbreaks.
Read Dr. Simao’s full report, including pictures here.
When returning to the United States after visiting a farm or being in contact with animals in a country (or countries) with African swine fever (ASF), or any other foreign animal disease, you should declare this information to US Customs and Border Patrol via written form, airport kiosk, or verbally. Then you should be diverted for an ag secondary screening by an ag specialist. The Swine Health Information Center (SHIC), National Pork Board, National Pork Producers Council, and American Association of Swine Veterinarians are asking you to report your experience if you are not diverted for secondary screening with return to the US following overseas travel.
If you are NOT diverted for secondary screening after declaring you have been on a farm or in contact with animals in an ASF or other foreign animal disease positive nation, please email the following to [email protected]:
Dr. Sundberg will be aggregating this information and the organizations will share with US Customs and Border Patrol to help identify any weaknesses in their protocol and systems.
ASF is endemic in Sardinia, most countries of subSaharan Africa, and some West African countries. Since August 2018, the spread of ASF through Russia, Belgium, the Caucasus, the Baltic states, Poland, and China has been monitored. At present, ASF has never been reported in the United States, Canada, Australia, or New Zealand.
Thank you for your help as we continue to implement steps designed to reduce the risk of ASF spreading to the US swine herd.
Does porcine circovirus Type 3 (PCV3) cause disease or is it just there? It feels counterintuitive to be talking about a type of circovirus and whether it really causes disease or not, but ultimately that is the question. PCV3 can, and has been, found in multiple tissues, samples and clinical signs. It is also found in healthy pigs. Thus, we have a question. Can it cause pathological lesions? Swine Health Information Center (SHIC) has sponsored research by Alberto Rovira, an associate professor at the University of Minnesota, to take a deep dive into past University of Minnesota Diagnostic Lab submissions. The goal is to mine diagnostics data obtained over the last two years and determine how closely certain clinical signs and pathologic lesions are associated with the presence of PCV3 alongside the viral load.
In the early 2000s, we had similar questions about PCV2. We had doubts it was linked with postweaning multisystemic wasting syndrome (PMWS) and porcine dermatitis nephropathy syndrome (PDNS). But increased death loss, subsequent diagnostics, and applied research eventually confirmed correlation. Consequently, we were able to take actions to control via vaccination.
With PCV3, the only two disease presentations associated with infection thus far are reproductive failure and PDNS. No co-infection with other pathogens has been reported. PCV3 was first isolated from a sow farm in North Carolina in 2015. In this case, incidence of disease, abortions, and mummified fetuses was reported as 12.5 percent. Deaths occurred among fetuses and sows. Exact numbers are unknown.
We now know PCV3 is widespread and has been around for decades. At the University of Minnesota veterinary diagnostic lab, PCV3 is found in 27 percent of samples and 35 percent of submissions in pigs of all ages and clinical signs. As an example, 40 percent of abortion cases, 25 percent of diarrhea cases, and 25 percent of respiratory cases were positive for PCV3. These studies, however, just looked to see if the virus was present. Histologic lesions were not reviewed. Subjectively, pathologists now suspect PCV3 may be associated with certain clinical signs and lesions. Lesions of vasculitis and myocarditis are suspected. Other clinical presentations such as PDNS, diarrhea, and respiratory problems are not perceived as being strongly associated with PCV3.
We currently lack true understanding of the clinical relevance of PCV3 and its ability to cause disease in pigs. This study will work to objectively assess the situation to better understand the presence and strengths of potential associations.
How vulnerable are your herds to porcine reproductive and respiratory syndrome (PRRS)? Want to know where to focus biosecurity? Gustavo Silva at Iowa State University, and his team, have devised a way to give farms a Biosecurity Vulnerability Score (BVS) based on surveys from Iowa State University’s PRRS Outbreak Investigation Program and data from the Morrison Swine Health Monitoring Project. This Swine Health Information Center-funded research shows that farms with higher BVS scores have broken more frequently with PRRS, adding validity to the scoring system.
The most important categories of risk events judged by the experts were those relating to swine movements, pickup/deliveries from/to premises, and people movement. The five most important events that occur in breeding herds related to PRRS introduction, as judged by the experts, were breeding replacement animals, semen delivery, air transmission, weaned pigs transported from premises, and dead animal removal, respectively.
To validate the BVS, Silva and team surveyed biosecurity practices and PRRS outbreak histories in 125 breed-to-wean herds in the US swine industry. Data on the frequency of PRRS outbreaks was used to test the hypothesis that biosecurity vulnerability scores were different between farms with a low incidence of PRRS outbreaks, compared to farms with a high incidence. In the two databases used, scores consistently showed that farms with higher scores have a higher frequency of PRRS outbreaks. Farms that had never had an outbreak investigation before had a significantly lower BVS score when compared to farms that had two or more outbreaks.
The BVS shows promise for assessing vulnerabilities on biosecurity protocols in order to reduce the frequency of PRRS outbreaks. And it may help producers and veterinarians prioritize investments in improving biosecurity practices over time. It can also be used to predict relative vulnerability of different farms within a production system and/or region based on frequencies of risk events since the probability of introduction of pathogens increases as the frequency of risk events increases.
The Swine Health Information Center’s Domestic Swine Disease Monitoring Report this week shows expected activity in December. Data for the report is collected from the Veterinary Diagnostic Labs at Iowa State, South Dakota State, and Kansas State Universities as well as the University of Minnesota. Porcine reproductive and respiratory syndrome detection decreased in December after two months of increase and remained in the predicted range the last three weeks of 2018. Porcine epidemic diarrhea virus detection by PCR also continues to meet expected values which means an increase in activity for the same time frame based on previous years’ reports. Streptoccocus suis remains the major agent causing CNS. For the beginning of 2019 winter, porcine circovirus had a greater percentage of detection, but similar number of cases, when compared with full winter season of previous years.
In the Swine Health Information Center’s January Global Swine Disease Monitoring Report, it is stated Heilongjiang province reported the largest infected farm since the start of the African swine fever (ASF) epidemic in China last August. A carcass positive for ASF was found on Taiwan’s shore. An ASF outbreak outside the control zone in Belgium was reported, close to the border of France. Additionally, the largest outbreak of CSF in a Japanese farm since its recurrence in last September was reported. Read the entire report, including actions by Chinese and Taiwanese governments related to the disease epidemics, here.