Disease Overview
ASF is endemic in many African countries, to which it was limited until 2007 when the ASFV entered the country of Georgia. It has since gone on to rapidly spread across Europe and now Asia, reaching China in August 2018. More recently, Cambodia, Hong Kong, Indonesia, South Korea, North Korea, Laos, Mongolia, Myanmar, Philippines, Timor Leste and Vietnam have all been affected.
The African swine fever virus (ASFV) affects all members of the pig family, including domesticated swine, European wild boars, warthogs, bush pigs and the giant forest hogs. ASF however does not currently pose a risk to human health as it cannot be transmitted to human beings.
The ASFV can be transmitted directly, indirectly through contaminated feed and fomites, or can be vector-borne and transmitted through ticks. Once the ASFV has been introduced, infected swine develop high viral loads which are easily shed and lead to further direct or indirect transmission via fomites, on items like contaminated clothing, shoes, equipment and vehicles. Infection through contamination (whether feed or, for example, mud on a transport vehicle) is considered to be of primary concern. This is why many European countries focused on raising awareness on biosecurity. This is also why there has been a drive to develop feed additives that can inactivate ASFV within feed.
Wild boar has also played an important role in spreading the disease; however, larger geographical leaps in the spread of the disease have been the result of human activity and the international transportation of domestic pigs. For example, the first outbreak of ASF outside Africa, was recorded in 1957 in Portugal, where it is presumed to have been caused by the feeding of pigs near Lisbon airport with food waste containing pork from Angola.
Implementation of ASF control methods varies among countries depending on the epidemiological status of the disease, that is whether its endemic or not, and the predominant type of pig production, traditional or backyard versus commercial.
Some of the most important biosecurity measures to prevent the entrance of ASF into a commercial farm include:
• Fences,
• Restriction of visitors and vehicles,
• Use of dedicated clothes and footwear,
• Safe disposal of carcasses,
• Avoiding the use of potential contaminated feed including swill.
• Introduction of new animals via quarantine and from well-known sources.
In fact, the Czech Republic demonstrated in 2017, after ASF was detected in two wild boars, how proper biosecurity measures can eliminate ASF. The country took various measures including increased passive surveillance, ban on hunting and wild boar feeding and enclosing the risk-area with “odour” and electric fences to ensure that the disease would remain contained and not spread any further throughout the country or the region. The last confirmed case of ASF in the Czech Republic was in February 2018.
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