(This information was sent to SHIC stakeholders on 8/3/18. Click here to read the entire report.)
The first case of African Swine Fever (ASF) was reported in China (LINK) on August 3, 2018. First identified on August 1, the outbreak was located in the northeast, in the city Shenyang, district of Shenbei New, in the province Liaoning, swine dense area 130 miles (208km) of the North Korean border. Infection on a small farm with a herd of 383 pigs, where 47 pigs died from the disease, was confirmed by China Animal Health and Epidemiolology Center on Friday, August 3, 11am, local time.
Veteran US pork producers will remember the intense and successful effort to eradicate pseudorabies virus (PRV) from the country’s commercial herd, completed in 2004. Unfortunately, there are two categories of PRV. Classical PRV has been eliminated in much of the developed world, but does reside in feral pigs in the US, Europe, Latin America, and Asia. The second PRV category, high path variant PRV, emerged in China in 2011. This variant causes severe PRV in vaccinated and nonvaccinated sows and pigs. Now, thanks to Swine Health Information Center (SHIC) sponsored research, we can discern diagnostically between classical and high path variant PRV with a single highly sensitive and specific PCR test, further protecting the health of the US swine herd.
It is a part of SHIC’s mission to protect and enhance the health of the United States Swine herd through coordinated global disease monitoring and targeted research investments that minimize the impact of future disease threats. Making sure we have the tools to diagnose key emerging pathogens is an ongoing key focus. SHIC has sponsored research that allows or updates detection of 17 prioritized swine viral pathogens like both PRV variants.
The newly developed PRV assay is highly sensitive, specific, and was able to detect as low as one infectious PRV particle in a sample while discerning between the variant and classical strain simultaneously. The assay did not detect other similar herpesviruses or swine viruses encountered in modern swine farms.
The assay was validated on nasal swabs, oral swabs, whole blood, serum, and tissues at the Kansas State University Veterinary Diagnostic Laboratory and at the National Veterinary Services Laboratory in Iowa. Specificity of the assay was further confirmed by testing over 300 clinical samples (serum, tissues, and swabs) collected from Canadian and US national herds.
PRV, a herpesvirus, is a disease no longer in the US commercial herd thanks to a successfully executed eradication program. Also called Aujeszky’s disease, it can infect other livestock and wild mammals, but pigs are the main hosts and reservoir for the virus. Clinical expression of the disease includes high morbidity and mortality in suckling pigs, respiratory problems in growing and fattening hogs, and reproductive problems in sows. Like other herpesviruses, infection of the nervous system is lifelong with periodic shedding. PRV does not infect humans.
In addition to the US commercial herd, Canada, Greenland, and Australia are free of PRV; however, classical PRV does exist in approximately 20 percent of feral US swine and 0 to 60 percent feral swine in Europe, depending on region. China has been positive for classical PRV since 1947. Since 1990, more than 80 percent of pigs in China have been vaccinated. However, in 2011, a highly pathogenic variant version of PRV emerged in China and was clinically expressed in vaccinated and non-vaccinated herds alike. These variant strains caused mortality rates up to 50 percent in suckling pigs.
Early detection and understanding sources of PRV are essential to contain spread and prevent economic losses, should the virus arrive in the US. The availability of a test to discern classical from the variant high path Chinese strain strengthens the US ability to respond quickly and effectively.
In incidents of high or ongoing morbidity or mortality, where an etiology is either not identified or there is a strong suspicion that the identified etiology is not the likely cause of the outbreak, SHIC continues to offer diagnostic fee support after the initial diagnostic workup is completed and paid for by the owner. In these cases, additional support for the fees of further diagnostic workup may help to identify newly introduced or emerging swine diseases. Find a description of the requirements, submission and review process for the Support for Diagnostic Fees Program on the SHIC website.
Senecavirus A (SVA or Senecavirus A) infection is indistinguishable from foot-and-mouth disease (FMD) and other swine vesicular disease, so every outbreak, including at harvesting plants, must be investigated. This takes significant state, federal, and producer time and resources. But the biggest risk of SVA is potential disruption of marketing chains during investigations at plants and other facilities. It was a close call in 2017. This investigation, funded by the Swine Health Information Center (SHIC) with in-kind contributions from the National Pork Board, reports about an incident where so many pigs needed to be held for investigation in the abattoir it threatened plant operations.
Introduction. On June 8, 2017, 10 loads of finishing pigs were tested by PCR for (SVA) at a packing plant in the Midwest United States. Six of the 10 were positive. Subsequently, a total of 74 lots from 61 suppliers tested positive for SVA between June 8, 2017, and July 10, 2017. This prompted an investigation to describe the outbreak and to identify factors that may have contributed to the spread of the virus during the outbreak. The investigation term was broken down to three time periods, the PreOutbreak Period from April 24 to June 7 (45 days), the Outbreak Period when positive cases were reported from June 8 to July 10 (32 days), and the PostOutbreak Period, after the last positive case was reported, from July 11 to August 8 (35 days).
SVA causes vesicular lesions around the snout, mouth, and hooves of infected pigs, but symptoms are rarely fatal and don’t last long. Clinically, SVA is indistinguishable from FMD and other swine vesicular diseases. These investigations take time and resources plus pigs and products can’t move until tests confirm the absence of FMD virus.
Methods. Data on lots of pigs sent to the packing plant during the investigation period were obtained from the plant records and satellite images of each supplier address via Google Earth. Weather data was obtained from Mesonet and Weatherunderground. A survey of biosecurity and management practices was also conducted on a small number of suppliers to the plant. Logistic regression was used to evaluate risk factors, QGIS software to map the locations of pigs delivered to the plant, and SatScan to detect and evaluate spatio-temporal (time and space) clusters of SVA cases. Descriptive analysis of weather data during the investigation period was also conducted.
Results. The timing of SVA cases for the outbreak investigated were consistent with a seasonal peak in cases reported by the Iowa State University Veterinary Diagnostic Lab since 2015, where the number of SVA cases peaks in summer months and declines in the winter. The most relevant findings were:
Conclusion. The findings indicate weather conditions in the PreOutbreak Period were favorable for multiplication of mosquitoes, and potentially flies and other insects, which may have contributed to the spread of SVA between sites. Whether mosquitos can serve as a vector for SVA has not been explored but the results of this investigation suggest it should. Single site suppliers with the presence of outdoor facilities had lower odds to be positive for SVA, suggesting multiple sites suppliers with contact with large production systems (e.g., shared equipment, trucks, etc.) may facilitate the transmission and spread of the disease. In addition, the presence of the packing plant inside the cluster suggests it may serve as a contact between the sites and act as a source of the virus.
In May 2017, the Swine Health Information Center (SHIC) released information from a study it funded showing the potential for viruses to contaminate and survive in feed ingredients. These surprising findings led to on-going research on transmission potential and mitigation. A meeting of stakeholders, including representatives of USDA, FDA, universities, industry organizations, producers, the feed processing industry, and SHIC, was held in June 2018. The objective of the meeting, hosted by SHIC and the National Pork Board, was to review current government policies and regulations and to make recommendations about research to help reduce the risk for pathogen transmission via feed and feed ingredients. A report from the meeting can be read here.
In addition to the prioritization of next steps, the stakeholder representatives heard updates from companies and federal agencies engaged in parallel work. FDA’s Center for Veterinary Medicine and USDA’s Animal Health and Plant Inspection Service both have regulatory authority related to feed safety. And USDA’s Center for Epidemiology and Animal Health will help with a review of the scientific literature and will bring experts together to discuss risk. SHIC is funding university and production company-related research to help define feed risk. And feed processing companies are also contributing to the body of work to help identify feed transmission risk and investigate mitigation. Programs were described and outcomes discussed during the meeting. Details are included in the meeting report.
1. Mitigation via verifiable controls
The action with the highest priority, mitigation, could include programs for verification of feed component safety prior to shipment from a foreign country. Possible methods discussed and recommended were block chain testing and traceability as well as preventative controls for animal food.
2. Active foreign animal disease monitoring at ports or importing countries
Active monitoring of imported feed components was ranked second by the stakeholders group. Monitoring for foreign animal disease and other transboundary pathogens at ports of entry, or before shipment from source countries, was discussed. Participants agreed this monitoring should be done at a foreign facility prior to shipment to the US.
3. Minimum and median infective dose of classical swine fever (CSF), pseudorabies virus (PRV), Senecavirus A(SVA)/foot-and-mouth disease (FMD) during normal feeding behaviors
Determining the minimum and median infective dose of key swine diseases CSF, PRV, and FMD during normal feeding behaviors was named an essential need. Using a National Pork Board grant, this is being done for African swine fever (ASF) at Kansas State University where similar tests for CSF and PRV can take place. Work with FMD must occur at Plum Island Animal Disease Center where SHIC, NPB and USDA-APHIS are co-funding the project. In addition to infective dose, mitigant effectiveness and survivability tests would be completed.
4. Active domestic monitoring
This monitoring would involve surveys of feed processing mills to measure the incidence of different domestic production pathogens found in these facilities.
5. Validation of environmental swab tools
Validation for dust sampling sensitivity using different materials, from commercially-available sheets to sponges, swabs, paint rollers, to other tools, would be conducted.
6. Detectability of other viruses via environmental monitoring
Research is needed to demonstrate the ability to detect viruses using environmental samples at various points in feed processing mills. Previously environmental sampling has been shown to be useful for detection of porcine epidemic diarrhea (PED) virus and SVA and that work would be expanded.
7. Tote contamination proof-of-concept
Testing for valid ways to sample totes as they carry feed into the country could be to sample the dust of a tote before, during loading, after loading, and after emptying to compare sensitivity of dust sampling to taking feed samples at the same times.
8. Rotavirus vs. Enterobacteriaceae as an indicator of possible contamination
Enterobacteriaceae are used as an indicator organism for fecal contamination of feed components. This experiment would compare rotavirus, or some other enteric virus, to these bacteria to investigate if it would be a better indicator of viral contamination.
Stakeholders agreed the goal should always be to prevent introduction of a FAD or transboundary pathogen from entering the US. Represented groups agreed about the urgency to investigate, define and mitigate the risk because of its potential as a pathway and the threat it poses to the US swine herd.
Part 2 of 3. (Read part 1 here.)
The Swine Health Information Center functions with the input and direction of its Board of Directors as well as two Working Groups. Working Groups are made up of veterinary practitioners, researchers, state and federal animal health officials, industry representatives, and producers.
Jim Niewold, a pork producer from Illinois, chairs the Monitoring and Analysis Working Group. Niewold, like his fellow Working Group members, brings years of experience in the pork industry to the mission as well as a desire to protect US swine herd health. “Part of the reason SHIC was created was to prevent being caught off guard again like we were with PED,” he explained.
The Monitoring and Analysis Working Group is charged with assessing domestic and foreign production disease risk using information from a variety of sources. They also help develop and advise on-going projects to monitor domestic swine diseases. In addition, the working group advises on data analysis projects that will support on-farm, producer decision making.
From his experience as a member of the National Pork Board (NPB) Swine Health Committee, the National Pork Producers Council (NPPC) Animal Health and Food Security Policy Committee, as well as work with the US Animal Health Association, the National Institute for Animal Agriculture, the USDA Secretary’s Advisory Committee on Foreign Animal Disease, and state level committees in Illinois, Niewold recognized SHIC’s ability to respond quickly in the event of a swine disease outbreak requiring immediate investigation and, when appropriate, coordinated intervention. “It is difficult for some organizations with traditional structure to react quickly because of their set budgets and requirement for expenditures to be approved in advance,” he explained. “Because SHIC is a separate entity, we react quickly with funds available to spend on something new if that’s what’s deemed necessary.” While SHIC is a separate entity, Niewold says NPB, NPPC, and the American Association of Swine Veterinarians (AASV) work closely together with SHIC.
One of the Monitoring and Analysis Working Group’s projects is review and prioritization of the Swine Disease Matrix. “We use three different criteria – production losses which create economic impact for producers, market access and trade issues, and the likelihood of introduction of the disease into the US or possibility of a disease existing in the US to start expanding,” Niewold remarked. The Matrix helps the Working Group guide research and determine what tests are needed.
“We would love to keep disease from entering the US,” Niewold stated. “Equally as important is to make sure diagnostic and other tools are available to so we can react more quickly, when needed.”
The Monitoring and Analysis Working Group is now developing and prioritizing a bacteria list that can present a risk swine health. “Originally, I didn’t think we’d go into that realm,” Niewold observed. “Now with the big push for less antibiotic use as well as antibiotic free production, we need to.”
As a result of SHIC coordination and with co-support from USDA, the Iowa State University, Kansas State University, University of Minnesota and South Dakota State University veterinary diagnostic labs are now able to seamlessly share data with each other. “We knew there was a wealth of information sitting there with no way to do anything with it,” Niewold stated. “Now with these labs standardizing the way they record test results, we are able to analyze and perhaps react sooner with that information.”
The Monitoring and Analysis Working Group is also responsible for monitoring the SHIC support of the Morrison Swine Health Monitoring Project. That includes the use of information technologies to reach the Morrison Swine Health Monitoring Project goal of developing the pork industry’s capacity for disease detection, response and continuity of business of producers.
As chair of the Monitoring and Analysis Working Group, Niewold sits in on the Preparedness and Response Working Group’s conference calls. “If the other group has a different opinion, as chairs we have a better idea about the big picture by participating with each other’s group, then we are more confident on any advice we need to pass along to the executive director,” he said.
In the next SHIC newsletter, the tasks and responsibilities of the Preparedness and Response Working Group will be highlighted.
In the July domestic disease monitoring report, for the first time, data on porcine reproductive respiratory syndrome virus (PRRSV) came from the Iowa State University Veterinary Diagnostic Lab (VDL) and South Dakota State University Animal Disease Research Diagnostic Lab with contribution from the University of Minnesota and Kansas State University VDLs. This is a result of the project the Swine Health Information Center (SHIC) coordinated and partially funded to streamline the way the VDLs report and share their data.
In July, an increased percentage of rRT-PCR-positive results for PRRSV was reported. The report also showed the seasonal pattern of porcine epidemic diarrhea virus (PED) is within the predicted values for 2018 while during recent summer weeks, porcine deltacoronavirus activity is also moving toward predicted values. Streptococcus suis continues to be the predominant agent detected in central nervous system tissue.
So far in summer 2018, Haemophilus parasuis appears to have higher activity for the 2018 summer compared with the summers of 2017 and 2016. This month’s report also begins reporting on pathogens associated with disease syndromes. This report includes data on tissues of respiratory disease syndromes submitted for investigation to the VDLs. PRRSV and Influenza A virus are the two main pathogens detected in respiratory tissue. Mycoplasma hyorhinis is appearing between top 10 more frequent agents detected in respiratory tissue in summer of 2018. This agent did not appear in the top 10 list for 2017 and 2016. Haemophilus parasuis has also been detected multiple times.
Last Friday the first case of African Swine Fever (ASF) was reported in China (LINK). First identified on August 1st, the outbreak was located in the northeast, in the city Shenyang, district of Shenbei New, in the province Liaoning, swine dense area 130 miles (208km) of the North Korean border. Infection on a small farm with a herd of 383 pigs, where 47 pigs died from the disease, was confirmed by China Animal Health and Epidemiology Center.