Talking global swine disease surveillance with UMN
African swine fever (ASF) is a highly contagious hemorrhagic disease that is often fatal in domestic pigs and wild boars. There are no risks to human health. Given the financial implications and limitations in trade, eradication of ASF is the ultimate goal.
In partnership with the University of Minnesota Swine Group and the Swine Health Information Center (SHIC), the Center for Animal Health and Food Safety at the College of Veterinary Medicine has taken a novel approach to strengthening the United States market against global swine diseases. The Swine Disease Global Surveillance Project compiles data from organizations, governments, producers and experts around the world to provide near real-time global surveillance of swine diseases.
Maria Sol Perez, D.V.M, Ph.D., with the University of Minnesota College of Veterinary Medicine, answers questions about what ASF is, where global outbreaks of ASF could occur and how the Swine Disease Global Surveillance Project identifies and tracks hazards that could put the U.S. swine industry at risk.
Q: What is ASF and how is it transmitted, diagnosed, and treated?
Dr. Perez: ASF is one of the most severe hemorrhagic diseases in pigs; it is caused by a virus and is often fatal, having a drastic impact on the pig industry. Because of this, ASF is listed as a notifiable disease by the World Organization for Animal Health (OIE), which means that all OIE member countries must immediately report any outbreak of the disease in their territory. The United States Department of Agriculture (USDA) considers ASF a foreign animal disease and, therefore, swine byproduct imports from ASF-positive countries are forbidden.
Infected wild boars and pigs are the main source of the ASF virus in infected countries. The transmission can occur by direct contact between infected and uninfected pigs, or indirectly, by contaminated swill feeding (uncooked pork products) or any objects or materials which are likely to carry infection, such as contaminated clothes, utensils or trucks.
Unfortunately, ASF presents a huge diversity of clinical signs. Early signs you may notice include: increase in the number of animals with purple ears and other parts of the body, fever, diarrhea and sudden increase of diseased animals and mortality. It is very important to highlight that ASF can have a much milder presentation in the field than what it is traditionally expected, misleading the early clinical diagnostic. ASF should be considered if any of the clinical signs described are found in combination with mild to severe increase in mortality.
Q: Where are outbreaks of ASF currently reported and is there a threat of a possible outbreak in the United States?
Dr. Perez: Since 2007, ASF has spread from the Caucasus region to eastern European Union countries. It then continued to spread westward affecting domestic pig and wild boar populations, making a long jump last September, reaching Belgium. Simultaneously, last August, it had its first incursion into Asia, where China, a major pork producer worldwide, reported its first outbreak. Since then it has expanded rapidly through China, reaching 31 out of 34 provincial-level administrative units. Since the first outbreak in China, many countries in the region were alerted and raised their control protocols in points of entry, considering that expansion regionally would be almost impossible to avoid. Confirming these concerns, last January, the first outbreak in a neighboring country was reported in Mongolia, and then in Vietnam and Cambodia.
ASF virus is highly stable, temperature resistant and can persist in the environment for a long time, making its control extremely challenging. The risk of introduction to free countries by contaminated pig products that travel long distances is therefore much higher than for many other diseases. Many countries around the globe with strong swine industries, like the U.S., have lately significantly increased their preventive efforts and protocols at many levels to minimize the risk of introduction of the disease, while working on preparedness measures to mitigate its impact as much as possible in case of introduction of the disease.
Q. How does the Swine Disease Global Surveillance Project gather data on the global occurrence of ASF? How frequently is the data reported?
Dr. Perez: The Swine Disease Global Surveillance Project (SDGS) compiles data from organizations, governments, producers and experts around the world to provide near real-time global surveillance of swine diseases. SDGS’s international network of collaborators allows the team to accurately interpret and contextualize that information.
We routinely do online searches, contact official agencies worldwide, and work with our international network of collaborators to collect and organize a combination of soft and official data. Then there are successive screening steps in which data and information is modified, edited, corrected, and expanded in collaboration with USDA/Animal and Plant Health Inspection Service Center for Epidemiology and Animal Health and selected stakeholders. Finally, a report describing the outputs are made available monthly within the SHIC report to the industry and to the public on a routine basis. Currently, the report primarily tracks three tier-one reportable foreign animal diseases in swine: ASF, classical swine fever and foot-and-mouth disease. We also include comments regarding other diseases that have a great impact on the industry when appropriate, based on the epidemiological context of the event.
Since the first report in November 2017, the project has published 24 reports that identify and track hazards that could put the U.S. swine industry at risk. After the first outbreak of ASF was detected in China in August 2018, the program increased the report output to bi-monthly—rather than monthly—reports to ensure the swine industry had the most up-to-date information.
Q: Where is the data available and what are examples of how the data could be used?
Dr. Perez: Swine disease data is available almost everywhere. The main challenge is building the proper steps of screening and filtering that will give consistency to the whole project. Currently, multiple official data sources such as government and international organization websites, international cooperation programs, and soft data sources like newspapers and unstructured electronic information are systematically screened to build a raw repository. After that, an include/exclude process is undertaken. As an output of this phase, a clean list of events is obtained, which will be scored using a multi-criteria rubric that was built based on credibility, and factors such as, scale and speed of the outbreak; connectedness; local capacity to respond; and potential financial impact on the U.S. market.
These reports have the goal to be an accessible tool for the industry to understand complex epidemiological contexts.
Q: Along with Swine Disease Global Surveillance Project, what are other ways you are preparing for and protecting against global swine disease?
Dr. Perez: The Center for Animal Health and Food Safety (CAHFS) is one of five OIE collaborating centers focused on veterinary service capacity building. As such, CAHFS has the mandate to improve the capacity of the official veterinary services and veterinarians in the field at national and international level, to improve the early detection, management and eradication efforts for diseases like ASF.
Diseases that impact trade do not respect borders and have the potential to spread quickly around the world, which creates a need to tackle these challenges as a global community.
This is why CAHFS and the Swine Disease Surveillance Project relies heavily on a global network of experts to continue to improve global health and protect against global animal diseases. While external partners allow CAHFS to accomplish more effective and efficient work, the University of Minnesota’s ingrained expertise in swine health also makes CAHFS the ideal center of the program’s research.
Maria Sol Perez is the deputy director of the Center for Animal Health and Food Safety at the University of Minnesota College of Veterinary Medicine. She builds on interdisciplinary evidence to inform best practices for the implementation of collaborative research and capacity building programs with international partners, to improve animal health and food safety in developing countries.
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