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SHIC-Funded Study Evaluates TADD to Inactivate ASF Virus in Transport Trailers

February 10, 2021 — Paul Sundberg

Swine transportation plays a major role in spreading infectious pathogens, including African swine fever virus (ASFV). Researchers from the University of Nebraska investigated if it is possible to effectively inactivate ASFV in the presence of organic materials (feces, bedding) through the use of thermal-assisted drying and decontamination (TADD) which commonly operates at the temperature between 63°C and 71°C. Results showed power washing surfaces with room temperature water followed by baking efficiently removed contaminated material.

Conducted in Vietnam, the study was made possible by funding from the Swine Health Information Center via a USDA Foreign Agricultural Service grant. Dr. Hiep Vu, Nebraska Center for Virology and Department of Animal Science, University of Nebraska-Lincoln, designed the study to determine the optimal baking time and temperature required to completely inactivate ASFV on aluminum surfaces contaminated swine feces. Testing for the inactivation efficiency of contaminated trays took place under three conditions:

  1. Baking contaminated aluminum trays at 54oC and 63oC for five, 10, and 15 minutes.
  2. Power washing the tray surface with water at room temperature followed by baking at 54oC and 63oC for five, 10, and 15 minutes.
  3. Power washing the tray surface with water, spraying disinfectant (Virkon-S), followed by baking at 54oC and 63oC for five, 10, and 15 minutes.

Two different methods were used to evaluate the efficiency of the treatments - PCR to detect viral genomic DNA and virus isolation to detect infectious virus.

In condition A, swabs collected from contaminated trays at all time-points post incubation at 54oC and 63oC were positive by PCR, indicating that heat treatment could not eliminate viral genomic DNA. However, swabs collected from contaminated tray at five minutes post incubation at either 54oC or 63oC were negative by virus isolation, indicating that holding ASFV in the presence of feces at 54oC for five minutes is sufficient to inactivate the virus.

In conditions B AND C, only two swabs collected after washing and baking were positive by PCR at high Ct value (e.g. 37.03). These swabs were negative for virus isolation. Thus, under the conditions of this study, power washing of the trays with water at room temperature, with or without the use of disinfectant, and then followed by baking efficiently removed contaminated material from the trays.

Collectively, results obtained from this research provide valuable information for the development of effective sanitation protocols to disinfect animal trailers to reduce the spread of ASFV.

As the world deals with the COVID-19 pandemic, SHIC continues to focus efforts on prevention, preparedness, and response to novel and emerging swine disease for the benefit of US swine health. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. SHIC is funded by America's pork producers to fulfill its mission to protect and enhance the health of the US swine herd. For more information, visit http://www.swinehealth.org or contact Dr. Sundberg at psundberg@swinehealth.org.

Paul Sundberg, Executive Director, Swine Health Information Center