Could ASF virus have been introduced into China through prohibited pork products carried by air passengers?
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1
Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, China
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2
Center for Animal Disease Modeling and Surveillance, School of Veterinary Medicine, University of California, Davis, United States
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3
China Animal Health and Epidemiology Center, China
Despite international prohibitions and recommendations, air passengers continue transporting plants or animal products in their luggage, which can lead to the introduction of exotic diseases or invasive species into a country. The number of air passengers entering China has dramatically increased in the last decade. This not only includes foreign visitors but also returning Chinese that have settled in Africa or other countries where diseases such as African swine fever (ASF) are endemic. Unfortunately, the first outbreak of ASF was reported in China on August 1st 2018 in Shenyang City, Liaoning province. As of May 6th, 2019, there were more than 130 outbreaks reported in 28 provinces and municipalities in mainland China. Recently, the disease spread rapidly into Viet Nam on February 19th, 2019 and Cambodia on April 2rd, 2019. We believe that one of the most likely pathways that could have brought the ASF virus (ASFV) into the country is the illegal introduction of pork products, particularly pork and pork products brought by air passengers from ASF endemic areas. Due to the long survival time of ASFV in various pork products and the high resistance in the environment, contaminated pork and pork products that are introduced by air passengers and eventually end up being used for swill feeding of pigs without heat treatment, could have leaded to ASFV infection of Chinese pigs, particularly in backyard production settings.
In this study we obtained information about the quantity and origin of ASFV contamination of intercepted prohibited pork products introduced by air passengers into three different international airports (A1, A2 and A3) in China during 2013 to 2017. We also gathered information about the ASF country status from the OIE as well as the flights and number of passengers entering China and estimated the potential amount of contaminated pork and pork products likely being introduced into the country per month and per year in the top ten international airports in China. Then, we used a quantitative stochastic risk assessment model to estimate the potential risk of ASFV release into China as well as the flight routes that are more likely to have air passengers bringing prohibited pork products potentially contaminated with ASFV and, therefore, help to prioritize and improve the sensitivity of the surveillance and border inspection controls. The results showed that the overall mean probability of ASFV introduction into the top ten international airports in China during one year was 0.175 (95% CI [0.017, 0.551]), with the Russian Federation flights the most likely route to have air passengers bringing prohibited pork products that could be potentially contaminated with ASFV (0.093, 95% CI [0.009, 0.241]). Shanghai Pudong International Airport (PVG) had the highest probability of ASFV introduction into China through prohibited pork products introduced by air passengers among the ten evaluated airports (0.068, 95% CI [0.010, 0.169]). We also observed seasonality in the probability of ASFV introduction through pork products carried by air passengers, with September (0.023, 95% CI [0.003, 0.065]) and November (0.029, 95% CI [0.000, 0.076]) being the months at highest risk. The probability of selecting an infected pork product from an ASF positive country was the most sensitive parameter of the model. The results of this study highlight the important role that prohibited products carried by air passengers may have for the spread of transboundary animal diseases and the need to increase border inspection controls, particularly in high risk airports and flight routes, and to invest in outreach and educational programs of air passengers to minimize the risk of ASF and other foreign animal diseases global spread.
Acknowledgements
We would like to thank the customs authorities of three international airports for their kind cooperation. This work was supported by National Key Research and Development Program of China (2017YFD0501806: “Trans-boundary model of animal-disease spread, and assessment of consequences and capacity of prevention/control”)
Keywords:
risk analysis,
air transportation,
release assessment,
Border Control,
illegal pork products,
Swine Diseases
Conference:
GeoVet 2019. Novel spatio-temporal approaches in the era of Big Data, Davis, United States, 8 Oct - 10 Oct, 2019.
Presentation Type:
Poster-session
Topic:
Special topic on African Swine Fever (ASF)
Citation:
Huang
Y,
Jung
Y,
Li
J,
Qian
Y and
Martínez-López
B
(2019). Could ASF virus have been introduced into China through prohibited pork products carried by air passengers?.
Front. Vet. Sci.
Conference Abstract:
GeoVet 2019. Novel spatio-temporal approaches in the era of Big Data.
doi: 10.3389/conf.fvets.2019.05.00098
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Received:
31 May 2019;
Published Online:
27 Sep 2019.
*
Correspondence:
Prof. Yingjuan Qian, Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Jiangsu, China, yqian@njau.edu.cn
Prof. Beatriz Martínez-López, Center for Animal Disease Modeling and Surveillance, School of Veterinary Medicine, University of California, Davis, Davis, California, CA 95616-5270, United States, beamartinezlopez@ucdavis.edu