DISCUSSION
The probability of ASF introduction into South Korea via legal imports
of live pigs and pig products was found to be negligible. The number of
countries eligible to export live pigs and pig products to South Korea
is currently 11 and 22 countries, respectively (Regions with an import
ban on designated quarantine products, Notification of MAFRA No.
2019-37, Enforcement on 30 July 2019). All import health requirements
(IHRs) for both items imported to South Korea stipulate that the
importing countries should be ASF-free for at least 3 years prior to
shipping. Of the assessed countries which exported live pigs and pig
products to South Korea, only two countries have suffered from ASF
outbreaks. In Italy ASF is restricted only to Sardinia and South Korea
imports pig products from the unaffected regions of the country. In
Poland with the highest probability via legal import of pig products ASF
has been present since 2014. However, an import ban on pig products from
Poland has been imposed immediately after the first ASF outbreak
notification in wild boars in February 2014. Countries with ASF
outbreaks are only allowed to import sterilized pig products to South
Korea (Regions with an import ban on designated quarantine products,
Notification of MAFRA No. 2019-37, Enforcement on 30 July 2019; Range
and criteria for sterilization, pasteurization and process of designated
quarantine products, Notification No. 2018-24 of APQA, Enforcement on 13
Sep 2018). This policy may also play an important role in blocking the
ASF risk of introduction through the legal imports of pig products.
The probabilities of release through the analyzed pathways were very
low, but the possibility of exposure to the pig population cannot be
ignored. In South Korea, swill feeding after heat treatment at 80 °C for
30 min is permitted. This heat treatment is below the recommendation of
the OIE (90 °C for 60 min) and, therefore, is more than likely not
sufficient to inactivate ASFV in the food scraps used for feed. In
addition, a high density of wild boars inhabits the country. Thus, ASFV
can be exposed to wild boar populations if they are able to access
landfills or other areas used for food disposal. To mitigate this
probability of exposure, heating food scraps at higher temperatures and
for longer time periods to feed pigs should be reinforced for a short
term. The proportion of food waste used for swill feeding and landfills
should be decreased and replaced with the production of biogas in the
long term.
Totally 14 ASF cases occurred during September-October 2019 in the
domestic pig farms of northern region of South Korea around the border
with North Korea. Pre-emptive slaughter and culling of domestic pig
farms in the infected region were conducted, while 485 cases have been
confirmed in wild boar population there from 2 October 2019 to 6 April
2020. The control of infected wild boars to block the further
transmissions to domestic pig population is of major concerns in the
country now. In spite of ongoing investigations, source of infection is
not specified yet. However, there is possibility of ASF introduction via
other routes like illegal import of live pigs or pig products, import of
feed, introduction of food waste from international airplanes/ships and
their use for swill feeding, and potential contaminated materials
carried by foreign workers, vehicles or other fomites. These pathways
need to be assessed and subsequent preventive measures should be
followed for the efficient concentration of limited quarantine personnel
and financial resources.