African Swine Fever Project in Vietnam Progresses Despite COVID-19 Pandemic

By Paul Sundberg

In 2019, the Swine Health Information Center (SHIC), with active support from the National Pork Producers Council (NPPC), received a grant from USDA's Foreign Agricultural Service division to fund a multi-phase project including African swine fever (ASF) field projects in Vietnam during the outbreak there. Objectives of these researchable priorities are helping Vietnamese response and recovery from the ASF epidemic as well as helping US pork producers learn lessons about ASF epidemiology and management. Despite challenges presented by the COVID-19 pandemic, progress continues on each of the related projects.

The USDA grant, "Building capacity to support the control of African Swine Fever (ASF) in Vietnam," has two sections. One section, "Implementation of field projects, and collection and analysis of samples," will help with industry preparedness and response in Vietnam and should ASF reach the U.S. Project topics and objectives follow.

ELISA

Two related projects include evaluating the performance of ASF serum and/or oral fluid ELISAs for use in the surveillance and monitoring of ASF outbreaks in commercial farms in Vietnam and in preparation for the virus becoming endemic in the US. More broadly, fulfillment of these projects will support a comprehensive integrated swine surveillance system ("no single best diagnostic approach") that takes advantage of a combination of molecular and antibody methods.

Rodents

This project will study if ASF virus can be detected in, or on, mice and rats on farms with ASF outbreaks, and if so, which tissues are the best to sample. In addition, research will look at the effectiveness of farms' biosecurity level on rodents' ability to bring in the disease onto the farm. Another project element will measure mouse-to-mouse transmission of ASF in a controlled laboratory situation.

Baking for Disinfection

Determining the optimal baking time and temperature required to completely inactivate ASF on aluminum surfaces contaminated with organic materials, this project is designed to simulate the sanitation protocols currently used to disinfect animal trailers.

Epidemiological Analysis of Pathways of Entry

With the rapid response outbreak survey of SHIC's Rapid Response Program, this project will identify likely pathways of ASF entry onto farms as well as test an electronic format for completing the outbreak investigation forms. The information can be used to improve on-farm biosecurity and streamline the process for US outbreak investigations, if or when they are needed as the US would start an eradication program.

Another related project on pathways of entry will assess the risk of ASF introduction into boar studs, the pathways of ASF introduction associated with semen movements into sow farms, the simulated spread of ASF in a sow farm in which multiple sows are simultaneously exposed to ASF via the AI process, and what surveillance is needed, and how long should semen be held, to increase the likelihood of ASF detection.

Composting

Funded by the National Pork Board, this project will assess the effectiveness of the swine carcass composting process to inactivate the ASF virus and using composting as a management tool. The project will also determine if regionally sourced carbon materials affect the composting process and subsequently the inactivation of ASF virus. Finally, it will determine if ASF virus survives in bone marrow during the compost process

Targeted Test and Remove

This project's objective is to evaluate "Test and Remove" methodology that hopes to identify an infection early enough in individually housed gilts or sows so they, and immediate contact animals on either side, can be removed to successfully eliminate ASF from the facility. Also, these field samples will be used to evaluate diagnostic performance of four commercially available ASF point-of-care, pen-side assays for detecting ASF in ASF-suspect and non-clinical neighboring animals.

Pen-Side Tests

Three different pen-side tests will be evaluated and compared using both whole blood and oral swabs as collected tissues. This project will work to determine the time from infection to the earliest detection using pen-side tests as well as the sensitivity and specificity of the pen-side tests for detection of ASF in the field.

Feed Transport and Mill Biosecurity

Another National Pork Board-funded project will develop a model to evaluate methods of cleaning and decontamination of transportation vehicles at facilities located at Kansas State University, using surfaces and conditions representative of real-world situations and evaluate multiple biosecurity strategies using porcine epidemic diarrhea virus (PEDV) in BSL-2 conditions there. Those results should then be able to apply lessons learned and build capacity to mitigate feed and delivery risk in Vietnam and the US, should the virus enter this country.